5 years later, and it seems like the newer filament type LEDs have found their best/cheapest compromise solution, which is to just use high-voltage series filament LEDs, linear regulator current limiting, and then solve the flicker effect by using longer persistence phosphors that just smooth out the flicker chemically instead of electronically. Simplest, cheapest circuitry, works with the existing TRIAC dimmers that stubbornly refuse to stop being produced despite tungsten bulbs being VERY obsolete, a tad inefficient because linear instead of buck regulation but it means they don't need a big chunky base to hold the driver circuit, and the pulses and overheating issues mean they last just as long as tungsten lamps so the companies can still make money! As for the issue of triggering the TRIAC, I have found a few lamp HOLDERS in the trash here in the US that include a small "capacitor to nowhere" that exists solely to make sure the TRIAC has enough inrush current to trigger, doesn't even need to be a BIG one, just enough to cause a 50mA spike for the usual BTAxx series TRIACs to fire.
I found this while looking for a dimmable teardown from him, trying to decide if I should invest in dimmables for the church fixtures. This explanation from the other side of it, though, ended up being more useful, if it's still accurate.
That would be nice to see. It's amazing how far they have come in just 5 years. I currently have a few fairly expensive "LED compatible" dimmer switches and modern "dimmable" LED bulbs in my bathroom and a few ceiling fans. I'd love to know how they work compared to the old style dimmers and last generation LED lamps.
Dammit Gummel! I did it again! Not as joke to myself and in honor of your awesome icon, but because I forgot! My screen is wearing away on the left. I keep forgetting. Oh, Crap! I want to know how to dim LEDs! Shit! There is a hair on my screen.... ;-)
The ceiling fans in hotel rooms would appear to be triac controlled - it's either full speed (too noisy/cold), half speed (annoying 100Hz buzz) or no speed (too hot). Either way it's impossible to sleep.
Top Tip: Hang your freshly washed linens on the fan's blades. This will slow the ceiling fan down, dry your clothes, freshen the air, and moisturise your face at the same time.
I doubt there are any semiconductors in a ceiling fan. The main reason being that the typical motors used in them (induction motors) can't really be "dimmed" by just chopping the AC. Usually the speed is controlled by switching between different capacitors.
As tech support for a company who makes SCR dimmers, having to explain to folks why they can't just swap out their old incandescents for LEDs is one of the most painful things I have to deal with. Especially if they've already purchased a set of 500.....
I think it would be a good idea to simplify the LED fixtures to be *just* a string of LEDs and a current limiting resistor. Then the dimmer would rectify and supply the variable voltage DC to the fixtures. Lower voltage = dimmed. When the fluorescent fixtures were too bright, they made a dimmer for each tube. It consisted of one plastic cylinder inside of the other. Each was printed with black stripes. When the cylinders were rotated so both stripes aligned, the tube was half dimmed. When the stripes were rotated to cover most of the tube, the light was very dim.
As an IT guy, I don't like the idea of light bulbs communicating over systems as complex as Bluetooth or WiFi. They are so easy to bugger up security... Look at what Philips did with their internet connected light bulb. A standardised, over the wire protocol would be fine. But I know that won't happen because its not as cool as an iPhone app to switch your lights on and off.
Uh, what? PoE is for powering remote network devices. Do you mean EoP as a communications method? Because that' still way to complex for a consumer grade light bulb. I'm thinking something more akin to "coax" SPDIF audio, but containing dimmer levels. Still insecure in that anyone with access to the wire can feed dummy signals, but far simple enough that a purpose made chip can receive it and process it without having an embedded Linux system (ala the hackable Philips bulbs).
well, often the light bulbs themselfs dont have WIFI but the controller of them has, but the controller - lamp is based on other protocolls (Ikea trådfri and philips hue).
There already are standards for controlling devices over the power lines. And they have exactly 0 security. All commands are sent in the clear, no encryption or signing. I too hate the bluetooth/WiFi controlled light bulbs, but without developing a new standard and somehow convincing everyone to adopt it, it's probably the best option security-wise.
I think the real future of LED home lighting is in integrated low voltage. It solves a lot of problems to stick your LED driver behind the wall switch, and have low-voltage coming out of the ceiling rose.
We're probably gonna end up with USB lamps and most wall sockets will just have a bunch of USB sockets instead of AC, and it's gonna take some work to run anything that requires AC at home.
Wouldn't help with dimming some LED bulbs, they would just be on at full intensity until you reached their cut off point then they'd switch off completely.
Rick Delair LED lighting in anything resembling real use doesn't damage eyesight, so you've 'solved' a problem that doesn't exist. (See, for example, www.machinedesign.com/blog/3-myths-surrounding-leds-0 )
I Suppose this also applies to the beefier theatrical dimmer packs. They replaced all of our house lights with the cheapest 'dimming' LEDs they could find as part of an eco-friendly initiative (never mind the fact they didn't even touch the 1KW Halogens and scoops) They've replaced dozens of bulbs that had a failure mode of dying, or my personal favorite, becoming a strobe light.
How odd, a couple of years ago I bought a cheap B&Q £9.99 dimmer switch and a dimmable LED bulb and it works great, no noise and no flicker. The bulb is a £14 Integral LED dimmable ILA60B22011D03KAIMA (3000K). On the other end of the scale, I tried a Poundland 3 watt bulb in my bedside touch lamp, it turned into a snake machine at dimmed times. Thanks for being awesome Clive. 😎
Look at LT3799 from linear technology... they already solved this problem. Any old phase angle controlled dimmers can be used to dim LED s fitted with that ic.
How about dimmers that use high frequency PWM to dim incandescent lamps ? You can dim anything with PWM, even gas discharge tubes... it just makes sense to use high frequency PVM to dim anything (including incandescent lamps, cfl tubes and LEDs).
I went to home depot and looked at some sylvania / osram dimmable LEDs. Not only were they like $30+ each, but the display ones bothered me with flicker. Down to about say half power they seemed ok, but below that threshold you could see the result of the sinewave being chopped up. Said works with standard wall dimmers. No, no it doesn't. I was less than impressed.
Current regulation is much more complicated than simple PWM control. Pulsing the LED is much more efficient and if done fast enough is imperceivable to the human eye or a camera.
Also, with the LEDs using phosphor coating for producing the final wavelength of light (pretty much all white LEDs and some color ones), current-based dimming causes a shift in color, PWM doesn't.
Higher end cameras and probably some of the new cell phone ones can deal with scan lines and PWM flicker. I'm not sure how. Shoot! I just realized that it's been a full decade since I worked in TV. :-(
I design Phase dim LED Drivers for volume manufacture. The one thing you forgot to mention is that it's the dimming system from hell. One further issue (of many) with triac dimmers is that diac can have different trigger voltages in each direction, so phase angles may not be symmetrical = 50Hz flicker which is even more noticeable than 100Hz. I could go on forever about the technical challenges, but I won't. The only true way to do this is to have a twin stage driver with advanced digital control. But such a circuit is very large with 40 to 60 components, generates more heat and is very difficult to fit into a bulb housing. There is also a USA flicker standard IEEE1789:2015 which if eventually adopted may make 99% of phase dim product obsolete or even illegal. I would also postulate that the terrible effect on mains currents ( very high THD/Harmonics) could be outlawed in future. Someone has commented... can you make your explanation more simple. The answer is no. Cheers, I enjoyed your video Jerry Senior Designer Harvard Technology
Well, I have 3 methods of control from my phone. 1. The method you described. 2. "Okay Google, Set bedroom lights to 50%" 3. I have a lock screen shortcut so no need to unlock my phone. I can also control from smartwatch in similar ways
Bleh, i hate this idea and I honestly hate smart phones too. Small, fiddly, annoying, have to arse around digging through multiple layers of apps/menus to get anything done. Having a physical button is vastly superior.
c'mon.... the next clive videos will be of how to hijack the super duper 128bit microcontroller with AI and get past the paid-per-month function "turn on"... it will be fun!!
Huh I just learnt something new, I thought dimmer switches were just variable resistors. Instead, they work more like analogue PWM. This explains why the one in my house made angry buzzing noises - until I removed it and replaced with with a normal switch so I could use LED bulbs in the room.
Yeah after typing that reply it did cross my mind that rheostats probably get a tad warm, and probably wouldn't be safe to embed in the walls of someone's house.
Reminds me of my internship where the speed of a three phase motor in a printing press was changed by switching massive resistors in and out. There was an entire wall stacked with them. Mind you this was just around 4 years ago!
Sounds like an old machine. The resistor banks are less efficient, but I bet that machine lasts longer and gives less trouble than one with electronic motor drives.
Recently I had to buy LED bulbs for my dimmable living room lamp [getting more difficult to find the tungsten filament type] and whilst the new LED says "dimmable" the buzzing is too annoying.
Do you think you could please make a video showing us in practical layman's terms what happens if you use an LED bulb with a dimmer? I thought you'd made such a video and maybe you have, but I couldn't seem to find one.
The Layman's terms as you put it... OK so a traditional dimmer will cause a standard LED bulb (non dimming type) to fail really quickly. Then when used on a LED bulb designed to be dimmed, the traditional dimmer switch would cause really bad flickering of the bulb. I have seen the results of both, and either effect is not good at all. Lowest cost option is to use a LED dimmer switch (most of them have a trimming adjustment of some kind), and a quality dimming LED bulb. This is not a perfect solution but works well with no flicker since you "trim" the switch to allow full range of the dimmer. The other option is to use a LED RF kit that has bulbs that use some sort of radio control, Bluetooth is the most popular one, since you can download an App that works with the bulbs. This allows you to control each bulb or groups of bulbs. Most of these offer all sorts of color options too. This sort of setup offers the most flexibility and can provide the best reduction in power consumption. Since you are not installing a dimmer switch in the wall that could potentially use more power then the LED bulbs would. With this setup you would only use a normal on/off switch. The main issue with this setup if the initial cost for everything, since the bulbs themselves are doing all the work. However since they are gaining popularity, the prices are dropping quickly. A year ago the Bluetooth bulbs were just over $40 for one, now you can find them for about $20.
I seen some bulbs that come with an RF remote control that allowed you to adjust the colour temperature and brightness and such, I thought they were good. I've been thinking of getting a couple of the LIFX bulbs but those are rather expensive.
Lachlant1984 You are absolutely correct there is all sorts of RF bulbs out there, the ones that come with their own remotes tend to be lower cost then the Bluetooth (form of RF signal) ones. The Bluetooth ones have the added benefit of not only having their own remotes (most of the time) but can also be controlled by certain things that uses Bluetooth like a tablet or smartphone for example.
Well, I went and had a fun adventure with a dimmer a while ago. First bulb I bought essentially strobed. It wasn't a flicker, it was outright strobing. That bulb apparently wasn't even a dimmable type, so I sort of chalked that up to me being stupid. Second bulb has been in the socket for about 2 years now, and it only lights up once the dimmer is about half way, but otherwise works fine. Hasn't failed yet.
One day lighting circuits will be low voltage DC, with the bulbs containing no electronics but the LEDs. Elsewhere will be a fairly beefy AC/DC transformer and the wall plates will just do PWM of the whole system in the room. Spraying RF around the house to control lights feels too inelegant and error prone - I've used cheap RF doorbells before, they're not very reliable and like to randomly go off. We have dimmable LED lights in some of our classrooms at work, and the wall switches are "clever" - press to turn on, press to turn off, hold to dim. Some of the bigger rooms have big switch panels with programmed presets to turn banks of lights on at set intensities. So we can press "1" to make the room full brightness, "3" for just the front lights, and so on.
With COB and filament technology low voltage high current DC is not a concern anymore. Mains AC can be rectified and fed into long chains of series LEDs controlled by a high-voltage buck regulator with PWM control. How to control? It's a matter of application. Choose from DMX, DALI, existing WiFi network. Something akin to homeplug ethernet might be interesting for domestic applications
Pretty much a noob at electricity, but how would you do this? Doesn't DC voltage drop over long distances with a decent amount of current? Seems like each light would be receiving differing amounts of voltage along the way through your house, so I dunno. Would you have the central transformer run all the wire at something like 12 volts and then have regulators at the base of each light?
I have lit a bar with about 15 meter of 12v ebay led strips, coupled with cheap pwm dimmers and a leftover computer power supply that is safely tucked away behind the audio rack. The whole thing cost about 25 euros.
Nice! I think one day houses will be wired with normal 110-220 VAC and some D.C. low voltage runs, maybe like USB type C that determine how much power is needed and set themselves to that level, if they can.
I too would like to see an update. I've replaced quite a few of the old bulbs with "smart" bulbs and I've noticed recently that there seems to be about a 2 year life span before thy start flickering, without any dimmer. So I'd guess the dimmer functionality you describe is built into the bulb? I had one replacement smart bulb that was on an occupancy sensor and it did as you described being very dim, so I had to keep that one as a fluorescent. I've had 3 different rooms so far (no dimmers) that smart bulbs have started flickering within a 2-4 year or so time frame. Seems there is a big difference in life span for smart bulbs vs regular LED bulbs, and certainly not what the manufacturer claims are
I've recently replaced a handful of LED bulbs within the last year that failed in 2 years or a little less, marginally longer than the 40 and 60 watt incandescents grew up with and loved and certainly much shorter life than the manufacturers claimed. The bulbs that failed seemingly early were used in enclosed fixtures meant for 60 watt incandescent, so heat build up could have been an issue, since LEDs prefer a cooler environment.
Idea: It seems many non dimmable LED lamps can be dimmed by a capacitor in series. Do you recommend this? Would it even be possible to use an adjustable capacitor to dim those LED lamps? Thanks for the great video!
I had this issue with a string of "dimmable" LED lights which flashed and had the sharp cut off as described in the video. The 12 LED bulbs only drew 48W on a 150W rated Lutron LED/CFL dimmer so I added one 60W incandescent light in an innocuous location on the string and the problem was solved with the full range of dimming and no cut off. Not exactly an elegant solution but the wife is happy.
I know Lutron have a device that replicates a resistive load without the need for using an incandescent lamp (which will blow in short order anyway). You'll need to terminate it in a suitable maintainable location, but it's a permanent fix.
Diac and Triac then onto Daleks. Run. Where is the Doctor when you need him? That leaves us looking for Sarah Jane Smith (Elisabeth Sladen, RIP) or Torchwood.
Clive how hard would it be to make a LED driver that was smart that can use PWM as a DIY project from the wall end of things and being able to still work with an incandescent lamp if someone happened to stick one in and not blow up the driver? OOPS foot in mouth. I was watching this as I was typing in and see that you covered it as I hit post. :p
FYI: In North America we have PWM replacement wall-plate dimmers (for old phase angle dimmers). they work well with LED CFL and Incandescent bulbs. They can drive any load up to 150W, smoothly dimming from fully on to barely visible and cost only slightly more than the traditional units.
Hi Clive, could you do an update on this subject. I’ve recently changed my kitchen down lighters from halogen to dimmable led and they seem to work fine on the existing dimmer that was in the house when we moved in 20 years ago. No buzzing or flickering from the lights or the wall plate. It used to buzz a bit with the halogens when on full tilt 9 lamps @ 50w each. I was actually surprised they worked having heard about issues with dimmable led.
Hi Clive, I've recently purchased a dimmable LED from IKEA (LEDARE E27 1000lumen £8) and paired it up with a V-PRO-IR From Varilight (screwfix (1220J)£15.99) It works really well and you can program the dimmer to a minimum dimming level that stops the LED light from strobe-ing and the dimmer has programable leading edge, trailing edge or Digiflux? modes, trailing edge is the default and works best with the IKEA LED bulb, I know it's not a chinese £1 purchase but it works really well. If it didn't cost £8 I'd do a bigclive on the lamp, perhaps when it fails!
Clive you popped my electronics cherry! haha...got my first breadboard, jumpers and power supply today and got an LED to light at different voltages and an LED with a salvaged diode to light too! I know that's some really low level corny shit but ya gotta start somewhere, right. ...bought some little motor toys and junk at the dollar store for components and tear down to see how stuff works too. haven't been THIS "spastic enthused" about anything since I was WAY younger and dumb...when shiny things and motorcycles were new to me n made me drool like a retarded monkey in heat. it's all your fault that I now own helping hands, breadboard stuff and the page and a half of tinker toys on my eBay purchase list....n the growing pile of electrical disasters waiting to be disastered on the floor in the corner now...n it gets bigger EVERY time the mail comes haha. THANKS for that! lol
You can now get dimmable drivers that convert phase angle to PWM for backwards compatability. the market is slowly catching up to customer demands. it's like they were so busy making and selling LED bulbs they completely forgot how Joe blogs is going to actually drive the things.
VERY interesting video! I wish I saw this when working at a store selling among lots of things light bulbs. I never got the hang of which LED bulbs where dimmable and why. Thanks for showing and explaining how complex it is!
The IKEA Lunnom lights (the slightly more expensive ones with the brass colored base) work really well with traditional dimmers. I was really surprised by the dimming range, and they don't flicker at all. Perhaps a teardown of one of those would be fun!
Perhaps a return of the auto transformer? It's kind of impressive that we have managed to make it difficult to dim a device that inherently has a linear(ish) voltage-to-lumen response.
I just have to say, I have learned more from your videos than i have from my high school before graduation. I've been watching for a while now and I must say I really enjoy learning, even if it is random from my point of view since I am not required to be on a specific topic now. once I accumulate the income, I plan on trying some of these circuits myself but that might take a bit of time. thank you for the knowledge.
which is why i put a 'ballast resistor' in parallel with the bulbs, just a pair of 3Kohm 10w ceramic power resistors in series is all it takes for 120V it also heps to lesser degree with CL rated dimmers in some cases
Try this: Go to IKEA, bring a high speed camera (240FPS should do). Film the aisle of light bulbs. When you look back at the video you will see about half the bulbs flicker badly. If you look which bulbs flicker you will see that ALL the "dimmable" ones flicker and all the "non dimmable" are perfectly smooth....
The long term solution might be to switch to 12 volt dc wiring for domestic lighting. I recently installed half a dozen Bonlux T22 E14 ac/dc 12V-24V, 2W SES clear filament LED bulbs (from Amazon) advertised for "RV Camper Marine, Truck, Boat, Solar Power" in wall-lights a wooden gazebo. I didn't want to get involved with mains wiring regulations so everything is fed from a 12 volt dc PSU housed in the nearby garage. The lamps are really good but are far too bright and despite the fact that they're advertised as non-dimmable, I decided to have a go at dimming them. I tried them first on a variable voltage dc lab power supply and they dimmed nicely, cutting off completely at about 6 volts. Feeding them with a PWM signal didn't work (as expected, because of the internal smoothing capacitor), but I designed a variable PWM circuit using a 555 timer and fed that into a P-channel MOSFET with smoothing afterwards (as used in a buck regulator). It works perfectly. The waveforms all look good on an oscilloscope and nothing gets hot. It needs a bleed resistor across the output to cope with low loads and the pot needs to be logarithmic so that the dimming is not all bunched up at one end of the scale.
you know there are dimmable led bulbs, i just wonder personally, do they work properly with a non-synced pwm dimming circuit (constant pulsewidth modulation)? i'm planning to make a digital dimmer myself, arduino nano, optocoupler, dual output transformer (+ - + to have a "separate" supply for the mosfet and arduino) and 3 fullbridge rectifiers (or 2 if i opt for an SSR, basically a TRIAC with an optocoupler)
so our lights need to be redone 100% where they are powered from the switch, then you will get led's that are nothing but a capacitor and maybe overcurrent protection? (high voltage PTC) and run from DC that was rectified and smoothed then have a high voltage buck constant current driver. you dont need to worry about ac being more efficient over the wires unless you have more than 200W of light which at that point some sort of wired controller would be in the price range. SO I SAY DC TO ALL MY DIMMEABLE LIGHTS
Are you saying that there may be LED bulbs that run purely on DC voltages and the dimmer uses PWM? Well, I suppose that's possible, what about 12 volt halogen lights? Does they run on 12 volts AC or 12 volts DC? If we were to change to DC powered lighting, it would need to be a complete full switchover for compatibility's sake otherwise you'd end up with hugs problems.
Halogen can run on either, they are basically a standard tungsten filament bulb filled with an inert gas. The L.E.D. only lights when reverse biased the DC circuit is fairly easy to control.
Sure. If we were designing from scratch, all our lighting would be DC, and at a voltage most suitable for driving LED lights directly. And I expect to see that happen in the long term. But here in the UK we need solutions that are compatible with all the old wiring that's already installed in old buildings. By the way, you also have to consider how you would control lights that are operated from more than one switch.
You seem to miss-understand, all the hardware fits into a standard socket the control is done via the start voltage and phase. although you could retrofit with dc lines to the lamp fixtures.
I recently installed VARILIGHT V-PRO DIMMER SWITCHES with Philips Warm Glow Dimmable LED. They work well. The dimmers are programmable for various modes and come on with a gentle 'boost' . The Lamps have a 'lightpipe' to simulate filaments and have two sets of LEDs (warm and cool) the cool LEDs shut down to 'warm' the light at lower settings. They will dim very low without flicker.
maybe a stupid question, but could one build a compatible dimmer that just (e.g. via some sort of variable resistance, dropping or even filtered PWM to produce a fake sine wave from a rectified input for more fancy/smart/whatever solutions) lowers the voltage? or would the LED drivers try to boost (or buck less) that to the maximum LED voltage and randomly flicker? if so, maybe just ignore the fact those things have rectifiers expecting AC and supply them with (very fast) PWMed DC (so it still flickers, but with a few KHz-MHz instead of ~110Hz)?
Great video Clive, been dealing with this issue recently. Currently split between replacing the dimmer with switches and using dual white LED lamps with a remote control+hub... or just putting in the most efficient lamp type that works with a dimmer.
Before triacs were available the PA dimmer used a SCR across the + / - of a bridge rectifier ! ( I have one and it still works ! ) .. the colour changing LED lamps use PWM and a remote controller ... a small step to " beef up " the lamp driver to supply big LED room lights , using similar hand held controller ( then remove your room's triac PA unit , fitting a normal on / off switch ? ? ) this must be the way for the future ?
I've had LED lights for quite some time, starting with Sunflux. I recently moved to a new apartment with built-it dimmers, and I found out that Ikea has some pretty good dimmable LED bulbs at around 3.50 €, ranging from 200 lumen to 1000 lumen. They are even just about the same size as old filament bulbs, and has a pretty good spread. Well worth trying! ;-) @bigclivedotcom - any chance of you taking it apart, analyze and show the workings?
You are exactly right. The dimmer (as opposed to "dimmable circuitry") should be in the bulb or fixture, and receive commands via the power line. One simple command protocol is Blink'n'Dim. A short power interruption triggers gradual dimming or brightening, and another halts it. Technology to achieve this is described on ResponsivLED.com. As of this writing, no fixture manufacturer has embraced it. However, a 0-10V Blink'n'Dim Adapter is available on Amazon for fixtures that include 0-10V dimming capability.
Came here thinking I could finally get an answer to my question as I'm trying to design this very circuit.. 24VAC to 35V pwm LED .. so far so good with triac decoder circuit. But question I can't figure out is if the phase angle is low (say 10%) then how would there be enough RMS voltage to power 35V led using PWM it's full brightness at less time but still uses full power🤔
One of the (many) jobs of a LE compatible driver is to damp out the oscillations between the dimmer and emc filter capacitors. On most drivers this is achieved by having an additional series R+C after the bridge rectifier (usually 220nF and 330 Ohms) What is not obvious is that this creates extra heat when used with a LE dimmer. Example : 10 watt lamp full power no dimmer ( or TE dimmer) driver power loss =2.5 watts. With TE dimmer at full power, driver power loss = 3.5 watts = 40% increase. Why be bothered? well extra heat means it won't last as long, so my advice is never use LE dimmer with LED lighting. Use TE ( trailing Edge ) types such as Varilight Vpro
I'm a bit late to the party but since Halogens seem to have disappeared those dimmers I bought for a £1 in flockdown were discounted for a reason. Meh. I saw Great Scott made a little dimmer the other day. Not exactly easy. Do you still stand by using funky, remote-controlled bling LED's in 2022?
I have a dimmable LED in a bedside lamp where you touch the base to vary the light intensity. However the lamp acts differently when using LED lamps as against incandescent lamps. When using LED, the light intensity is 0.5, 1, 0.25, Off ( so 4 touches of the base to cycle through) When using incandescent , it is 0.25, 0.5, 1, Off Any ideas why?
Would pulse-width modulation (fitted between the bridge rectifier and the LED itself) not be one possible option for dimming an LED light? As I understand it, LEDs easily tolerate rapid on-off switching, and some battery powered LED torches or head-lamps already use PWM to provide different brightness settings. Another possibility: A miniature variac (directly rotated by the dimmer knob) fitted within the wall-plate, to adjust the AC voltage fed to the LED lamp. Of course a variac that small could only handle a few watts (maybe a few tens of watts at most), but LED lamps only use a few watts anyway, so that should work, should it not?
Those damn TRIAC dimmers caused me many a heartache as an AM radio (MW) fan... The harmonics from that nasty clipped AC would make any nearby AM radio spit out an annoying 120Hz BUZZ. The harmonics would affect up into the HF shortwave band and even to the 6m 50MHz band!
+bigclivedotcom - Thanks for addressing this. -- What about a low-voltage supply for lighting? Accent and Landscape lighting use (I think) 12v a/c? As the LED lamps are being pushed into replacing tungsten, any LED bulb could simply rectify the power, as most LED bulbs already do. Any dimmer could rectify, smooth and then PWM the power. It would certainly not happen overnight, but separate lighting and non-lighting wiring could become the new norm. Somebody is gonna have to rewrite a bunch of code and regulations.
Most new LED lights require a ELV (electronic low Voltage) noise reducing dimmer. If you are having issues using dimmers on LED lights save your self a lot of headaches and just purchase a Viribright LED dimmer switch. ELV 300VA 2 way or Single Pole. for like $16 on amazon
Here is some more information if anyone is interested. You shouldn't use leading edge dimmers with any tipe of LEDs, even those with linear drivers which swich how many LEDs are in series. Voltage spike is so big that they can't react fast enough and even small capacitances arround the board make a big difference. (I wouldn't use leading edge dimmers anywhere thease days because some of them make so much noise they affect celphone, WiFi, Bluetoth...) You can use trailing edge dimmers on most LED lamps with some kind of linear control as said in the video but the problem is not only flickering bacause of ON/OFF but zero cross detection too. LEDs are so fast you can see 0,5% jittering and with so much noise on the power lines these days zero cross detection is not that easy. (We set the minimum for this type of dimmer to 25%) so the jittering is not so visible, but it is still there if you look for it.) There are many different options for dimming but they normaly start with dedicated LED power supplys at arround 25W and up, they are a bit more expensive but you can get a good brand for arround 20€/$ and they last for years. We mostly use 3 types of dimming: 1.Push button (for old instalations where wires are already in place and you can't use low voltage lines (Short press is ON/OFF, long press is dimming) 2. simple potentiometer normaly 100k ( thease type of power supply are the cheapest and the best in general, the probelem is you should have a cable directly from the lamp to the potentiometer at least 20cm away from mains power). 3. 1-10V (If you want to control more than one light at the time and you can easily add WiFi/ Bluetooth to this line) There are many others like DALI,DMX,KNX,Bluetooth, WiFi, LAN,... but for now I would advise to just use them for playing arround and not controll the whole house on it because one day it fails and when it does it takes a week to set up again. Leave those to companies, shops, entertaiment and people with too much money xD
A few years ago, I bought an expensive Philips LED bulb (similar to www.extremetech.com/electronics/128669-philips-new-100w-equivalent-led-bulb-runs-on-just-23w) and I will say that I can see why it was expensive. The colour of the light is the best of any LED lamp I've ever seen, it's beautifully dimmable, and it's lasted for ages without losing light output. It certainly beats any IKEA or Osram LED bulb I ever bought. That isn't to say it was worth the £30-odd it cost, and I'll not get that back in power savings, but it is a really great bulb.
Resistive load vs. reactive load. The old filament lamps are resistors, where the phase angle between voltage and current is zero. But with reactive components as a load, such as capacitors, then the phase angle between voltage and current is no longer 0 degrees. God knows what the phase angle is because all lamps are different. It's a wonder to me that manufacturers have managed to make dimmers work with today's LED lamps. It's probably going to require some new standard for LED lamps and dimmers to fix this issue so that all LED lamps and dimmers present identical loads to one another. Remember the old X10 systems that Radio Shack sold long ago? Those things passed a high frequency signal (100 kHz?) through the power line that could talk to the receiver. These days they might use a wireless RF link instead. If that ever happens, we'll see the opposite of today's dilemma, where it's the old filament lamp that won't dim when used with the new LED-only dimmers. Just on/off, and that's it.
I have a cheap LED bulb with capacitor dropper and a simple switch with a neon bulb in parallel built in and when I turn the switch off the LED bulb dims down from 30W TL-D brightness to 1W fluorescent night light level, it has been operating like this for months and doesn't look like it's going to die anytime soon. So here's a thought: is it possible to use a neon indicator light in parallel with the dimmer to make it work on some LED bulbs?
Here in South Africa we have a company that has patented a so called "Universal Dimmer". I have bought one and it works really well. It will dim my non-dimmable 230VAC downlights without problems. Although I have noticed it doesn't work on all brands 100%. Apparently the dimmer is only compatible with constant voltage and constant current drivers. Here is the link: www.caelus.co.za/inc/pdf/Understanding_alldimmer_2015.pdf & www.caelus.co.za/inc/pdf/alldimmer_web.pdf
I use a dimmer made by LightwaveRF which at around £40 each isn't cheap and if you use 'normal' led bulbs they flash but LightwaveRF say to use Megaman LED bulbs which Megaman is something to do with LightwaveRF and those bulbs work fine with the dimmer but once again the bulbs aren't cheap either. I think all in all I spent almost £70'ish just for a straight forward dimmer and 3 GU10 LED Bulbs. I wouldn't of normally gone for this but the dimmer ties in to my home automation stuff so I wasn't to fussed.
The end of your clip? You are holding 2 lamps, an LED and a filament type. The LED light in your left hand is one of those LED strings which just runs on main, no circuitry at all. That one could be dimmed if we would have a switch with extra leds in it. The leds would cause a voltage drop, which will lessen the current. So we get a switch which lights up (a dimmer), and the main light would dim as well. On the other hand, the LED light in your left hand does flicker to a point where it gets very annoying. (the main reason for my idea to do it this way is so that we are not throwing away any power loss and have a true dimming). Of course I understand this dimmer will be fixed for the led light because the current must be equal. But hey, it is just an idea. I see many other possibilities like using a dc to dc controller for instance.
What does actually happen if you REALLY run LED lamps with various kind of dimmers (with resistive/capacitive/switch mode power supply circuits inside)? I understand it in theoretical level but I really want to know what actually happens to them. p.s. And CF lamps too!
As far as I know, there is a 0-10V or 0-5V system in use. Probably just plain potentiometer using referance voltage from the LED driver. But that's not the classic LED bulb, I would expect a rather integrated system where the knob only goes to the lamp, and do not have mains power going via it. Probably worthy a review, but likely not the cheapest!
If they're going to develop new wallplates (that would be signalling the lamps over power or via RF), then instead of again switching all the LEDs on and off (albeit quicker this time, using high-frequency pulse width modulation), would it not make more sense to design the lamps compatible with a clean-slate dimmer-to-lamp protocol so that these "dimming 2.0"-compatible lamps would consist of multiple LEDs, and would only drive some of their LEDs, depending on what the dimming 2.0 protocol tells them?
Don't you have the flickering problem with florescence lamps with a traditional ballast thingy? But the main problem I see here is that we still use that damn AC from the last century/millenium... The problem with this shit is that you need a variable power supply, for DC-DC it's not that hard to do, you "just" need a variable buck/boost converter... So in theory, it's completely possible to make such a thing. The problem I see: Is it possible to make it small enough (and with high enough build quality) that it fits inside the wall? Or would it be just too big if you want to make a decent voltage regulating device (well, that's what Dimmers to, if in a rather shitty way)...
I personally like to use thoose cheap COB led from china, like ebay or aliexpress, with a variable dc-dc step down converter with variable current limit (the LEDs are about 0.5€, and the dc-dc converter arround 2€... quite cheap actually). If you use the current limit feature just below full power, you can effectively dimm the light with little to no noise... and no flickering that i could notice.... The problem is to design that to be able to control it from the wall while using standard lights... How about the led's power, thoose who don't know about it would probably just pump too much current trough the led and burn it... And you'd need to have an ammeter somewhere to control the top amp if the dc-dc limit is over the LED's... That would be too complicated to normal ppl arround...
Since LED lamps seem to have quite a few individual LEDs, why not turn on and off banks (or even individual) of LEDs? For very low light level, turn on six LEDs, and ramp up six at a time to 72. That would give 12 steps on a 72 LED chip.
Instead of PWM to control all LEDs in the light, would it be possible to use the sine wave to turn a percentage of LEDs on? For example, at 100% all LEDs are on, and when the dimmer is at 50% then only 40% of the LEDs are on (I'm assuming it's not a one to one ration for power in to what the human sees). That way, hardly any flicker as it's no longer PWM controlled...
One thing that maybe of interest Clive is ZEGALED a USA company distributing product sourced from 'Sunfor' in China. The bottom line here is long persistence LEDs by the use or rare earth materials which in theory massively reduce flicker. I have had no success in testing these. Do you have the contacts to get some? The LEDs themselves are called REAC LEDs and are primary intended for ac led solutions ( bridge and current limited LED string..no large caps). Jerry
Since you have LED lamps with and without the drivers, that makes it a mess to try and work around it directly from the supply. As you said, if it has a smoothing cap, you can't really do anything, since the buck driver would just work harder to output. So isn't the problem coming from more of a "missing standard" on what an LED lamps contain? So making a matching pair of dimmers and dimmable LED lamps, would work the best?
I am using 3 brightness level LED globes, controlled by switching them on/off multiple times to get a dimmer light output. So at the first on state, they are at full brightness & each following power off/on cycle reduces the brightness level (twice in total), then they are back at full brightness at the third cycle! The globes did cost a little bit extra, but it is worth it!
This is a pretty good explanation, however is is somewhat "Clive-centric". Here in Australia, the use of capacitive droppers is pretty rare, as those lamps don't comply with EMC or power factor standards. Also, the use of PWM is not the easiest way to control LED brightness, nor is it the way that dimmable lamps are controlled. Modern chips adjust the output current, and they internally handle power factor as well. A single-chip buck with current control and PFC is extremely cheap with low component count.
I have a new Philips R7S LED Dimmable working perfectly with a Legrand wall Dimmer. I have tried a Philips and other branded G9 dimmable with ceiling fan light but it doesn't work properly
According to the latest technology I've seen, the dimmer module varies frequency, the supply to the LED is rectified to DC so the LED does not care about the frequency but......... Their are two (glass or plastic )envelopes around the LEDs with a gap for a substance which becomes less opaque (more transparent) at higher frequency controlled by the on board electronics.
Fun fact: Leading Edge was a computer company that made 386, 486, and Pentium systems in the late 1980s and early 1990s. They had a few modems as well.
This is why commerial installations used voltage or current controlled lamps, running at 24 to 50 volts. They are connected to the mains via dedicated drivers and power supplies. The drivers themselves are dimmed using DMX, DALI or 1 to 10 Volt signals. One driver can control a numerical of leds, and a suitable PSU could feed a number of such drivers. Essentially the lighting is a low voltage installation. Direct mains dimmable Leds are for existing installations where rewiring isn't practical.
Wonder if you can get away with rewiring your house to where the lights go off at say...a 12 volt power supply, running 12V LED lights off it, and just putting PWM circuits where you want dimmable switches. At least if there's a blowout, you could have light off a car battery or similar.
Been using Dimmers extremely sparingly with CFL bulbs. Mostly because of ahem. it's supposedly rather dangerous and I tell people who use CFL's with dimmers. pop the dimmer all the way on and leave it there. (and many of these are in enclosed ceiling lamps smh ahem anyway. Hadn't thought about LED's yet. Some of the LED c7 bulbs I've stuck in night lights designed for incandescents light up even with the power off. So I'd imagine trying to dim them would be complicated since they light up with a very low voltage.
Clive, Every year I put LEDs outside my mates house and we can dim the LED's using an 3 or 8 channel control board comprising of a triac, A control chip, A few odd components and the input from the computer... Yes we do the sound to light for christmas but we dont use the american stuff. We have full control of the dimming of the LED's either strings or the RGB strips.
White LEDS are actually ultraviolet LEDs with a phosphor layer that converts the ultraviolet radiation into visible light. The phosphors have an afterglow similar to the afterglow of an incandescent lamp filament, greatly reducing the flicker when driven with 50-60 Hz mains power.
All dimmable lights strobe. All of them :( please correct me if I'm wrong, I will be very happy finding one. I have tried nearly every make of 'dimmable' bulb and they all flicker, even the expensive Philips and Osram ones, some worse then others. Doesn't matter if your use a dimmer or not, or a traditional dimmer or a trail edge dimmer, even in a straight on off switch like a lamp they seem to strobe/flicker when tested on a slow record. The quick test I did was slow motion video on the iPhone where you can see the strobing on all dimmable leds. Even get strobing on all hallogens (they can all dim). However, a few straight non dimmable leds I tested (like both Philips core pro 11 and 13 watts were completely stable). I'm dreading to think that no dimmable leds that don't strobe even exist. Even if my eyes can't see the dimming, and only in very slow motion you notice it, I'm sure my migraines come from them. Has anyone else tried this iPhone test? I am completely wrong with how I'm testing or am I right and all bulb manufacturers offering dimmable bulbs ruining our health?
5 years later, and it seems like the newer filament type LEDs have found their best/cheapest compromise solution, which is to just use high-voltage series filament LEDs, linear regulator current limiting, and then solve the flicker effect by using longer persistence phosphors that just smooth out the flicker chemically instead of electronically. Simplest, cheapest circuitry, works with the existing TRIAC dimmers that stubbornly refuse to stop being produced despite tungsten bulbs being VERY obsolete, a tad inefficient because linear instead of buck regulation but it means they don't need a big chunky base to hold the driver circuit, and the pulses and overheating issues mean they last just as long as tungsten lamps so the companies can still make money! As for the issue of triggering the TRIAC, I have found a few lamp HOLDERS in the trash here in the US that include a small "capacitor to nowhere" that exists solely to make sure the TRIAC has enough inrush current to trigger, doesn't even need to be a BIG one, just enough to cause a 50mA spike for the usual BTAxx series TRIACs to fire.
4 years on, I’d like to hear how things have progressed! Maybe you’d consider doing an updated version of this video?
Yes
Yes please!
I found this while looking for a dimmable teardown from him, trying to decide if I should invest in dimmables for the church fixtures. This explanation from the other side of it, though, ended up being more useful, if it's still accurate.
That would be nice to see. It's amazing how far they have come in just 5 years. I currently have a few fairly expensive "LED compatible" dimmer switches and modern "dimmable" LED bulbs in my bathroom and a few ceiling fans. I'd love to know how they work compared to the old style dimmers and last generation LED lamps.
Yeah
5 years on, I’d like to hear how things have progressed! Maybe you’d consider doing an updated version of this video?
You have copied Charlie Graham's comment lol
Your knowledge in electronics and your effort to post videos everyday is astounding! You should be honored as a national treasure
I thought there was a hair on my screen, nice picture!
Dammit Gummel! I did it again! Not as joke to myself and in honor of your awesome icon, but because I forgot!
My screen is wearing away on the left. I keep forgetting. Oh, Crap! I want to know how to dim LEDs! Shit! There is a hair on my screen.... ;-)
I also fell for your icon. I am amused.
The ceiling fans in hotel rooms would appear to be triac controlled - it's either full speed (too noisy/cold), half speed (annoying 100Hz buzz) or no speed (too hot). Either way it's impossible to sleep.
Top Tip: Hang your freshly washed linens on the fan's blades. This will slow the ceiling fan down, dry your clothes, freshen the air, and moisturise your face at the same time.
Genius top tip :)
Actually these things are adding windings at different angles, but I agree on the effect
I doubt there are any semiconductors in a ceiling fan. The main reason being that the typical motors used in them (induction motors) can't really be "dimmed" by just chopping the AC. Usually the speed is controlled by switching between different capacitors.
And render all your freshly washed linen filthy from all the dust that your ceiling fan picked up :p
As tech support for a company who makes SCR dimmers, having to explain to folks why they can't just swap out their old incandescents for LEDs is one of the most painful things I have to deal with.
Especially if they've already purchased a set of 500.....
Ezra Knickelbine I’d imagine that would be a nightmare. Almost a don’t shoot the messenger type deal isn’t it?
I think it would be a good idea to simplify the LED fixtures to be *just* a string of LEDs and a current limiting resistor. Then the dimmer would rectify and supply the variable voltage DC to the fixtures. Lower voltage = dimmed.
When the fluorescent fixtures were too bright, they made a dimmer for each tube. It consisted of one plastic cylinder inside of the other. Each was printed with black stripes. When the cylinders were rotated so both stripes aligned, the tube was half dimmed. When the stripes were rotated to cover most of the tube, the light was very dim.
As an IT guy, I don't like the idea of light bulbs communicating over systems as complex as Bluetooth or WiFi. They are so easy to bugger up security... Look at what Philips did with their internet connected light bulb.
A standardised, over the wire protocol would be fine. But I know that won't happen because its not as cool as an iPhone app to switch your lights on and off.
agree, IOT = security disaster.
. . power over ethernet is already here
Uh, what? PoE is for powering remote network devices.
Do you mean EoP as a communications method? Because that' still way to complex for a consumer grade light bulb. I'm thinking something more akin to "coax" SPDIF audio, but containing dimmer levels. Still insecure in that anyone with access to the wire can feed dummy signals, but far simple enough that a purpose made chip can receive it and process it without having an embedded Linux system (ala the hackable Philips bulbs).
well, often the light bulbs themselfs dont have WIFI but the controller of them has, but the controller - lamp is based on other protocolls (Ikea trådfri and philips hue).
There already are standards for controlling devices over the power lines. And they have exactly 0 security. All commands are sent in the clear, no encryption or signing. I too hate the bluetooth/WiFi controlled light bulbs, but without developing a new standard and somehow convincing everyone to adopt it, it's probably the best option security-wise.
Well crap. I was hoping that you had a dimming circuit for LEDs.
I think the real future of LED home lighting is in integrated low voltage. It solves a lot of problems to stick your LED driver behind the wall switch, and have low-voltage coming out of the ceiling rose.
We're probably gonna end up with USB lamps and most wall sockets will just have a bunch of USB sockets instead of AC, and it's gonna take some work to run anything that requires AC at home.
so why is 50/60Hz the norm? is it ideal for transformers or is it an arbitrary number that simply wasn't changed.
At the time it was the chosen as being a frequency that was easy to generate. It's maybe not what would be chosen if we could start again now.
Why did you refer to it as 100 to 120 times a second? Why would it not be referred to as 50 or 60 times a second?
What about 0-10V controlled drivers? Wave of the future or relic of the past?
Bah, bugger all this namby-pamby dimming - just bolt a variac to the wall! :-P
Wouldn't help with dimming some LED bulbs, they would just be on at full intensity until you reached their cut off point then they'd switch off completely.
Is there really a need to dim LEDs below their cut off point?
Rick Delair LED lighting in anything resembling real use doesn't damage eyesight, so you've 'solved' a problem that doesn't exist. (See, for example, www.machinedesign.com/blog/3-myths-surrounding-leds-0 )
I Suppose this also applies to the beefier theatrical dimmer packs.
They replaced all of our house lights with the cheapest 'dimming' LEDs they could find as part of an eco-friendly initiative (never mind the fact they didn't even touch the 1KW Halogens and scoops) They've replaced dozens of bulbs that had a failure mode of dying, or my personal favorite, becoming a strobe light.
How odd, a couple of years ago I bought a cheap B&Q £9.99 dimmer switch and a dimmable LED bulb and it works great, no noise and no flicker.
The bulb is a £14 Integral LED dimmable ILA60B22011D03KAIMA (3000K).
On the other end of the scale, I tried a Poundland 3 watt bulb in my bedside touch lamp, it turned into a snake machine at dimmed times.
Thanks for being awesome Clive. 😎
Interesting video. I've always thought that a dimmer switch was just a high voltage rheostat.
Look at LT3799 from linear technology... they already solved this problem. Any old phase angle controlled dimmers can be used to dim LED s fitted with that ic.
But then you need a fancy IC to do the magic... and that still throws PFC out the window...
How about dimmers that use high frequency PWM to dim incandescent lamps ?
You can dim anything with PWM, even gas discharge tubes... it just makes sense to use high frequency PVM to dim anything (including incandescent lamps, cfl tubes and LEDs).
I went to home depot and looked at some sylvania / osram dimmable LEDs. Not only were they like $30+ each, but the display ones bothered me with flicker. Down to about say half power they seemed ok, but below that threshold you could see the result of the sinewave being chopped up. Said works with standard wall dimmers. No, no it doesn't. I was less than impressed.
Cover the LED in an LCD shutter ;-)
A bit wasteful though
Variable opacity perhaps?
PWM is not a end all solution as video cameras can pick up the flickering which shows up in the footage.
It depends on the speed of the PWM versus the shutter speed. High and low frequency PWM each have their own advantages.
Current regulation is much more complicated than simple PWM control. Pulsing the LED is much more efficient and if done fast enough is imperceivable to the human eye or a camera.
Also, with the LEDs using phosphor coating for producing the final wavelength of light (pretty much all white LEDs and some color ones), current-based dimming causes a shift in color, PWM doesn't.
Frequency of the pulse matters a lot, of course. 50-60hz isn't going to cut it if you don't want flicker on camera.
Higher end cameras and probably some of the new cell phone ones can deal with scan lines and PWM flicker. I'm not sure how. Shoot! I just realized that it's been a full decade since I worked in TV. :-(
I design Phase dim LED Drivers for volume manufacture. The one thing you forgot to mention is that it's the dimming system from hell.
One further issue (of many) with triac dimmers is that diac can have different trigger voltages in each direction, so phase angles may not be symmetrical = 50Hz flicker which is even more noticeable than 100Hz. I could go on forever about the technical challenges, but I won't.
The only true way to do this is to have a twin stage driver with advanced digital control. But such a circuit is very large with 40 to 60 components, generates more heat and is very difficult to fit into a bulb housing.
There is also a USA flicker standard IEEE1789:2015 which if eventually adopted may make 99% of phase dim product obsolete or even illegal.
I would also postulate that the terrible effect on mains currents ( very high THD/Harmonics) could be outlawed in future.
Someone has commented... can you make your explanation more simple. The answer is no.
Cheers, I enjoyed your video
Jerry
Senior Designer Harvard Technology
led dimmers are now mostly based on pwm motor controllers with a few extra output smoothing components
The Future of LED Lamps is control from the smartphone. Then all the circuitry can be contained within the bulb. as with Philips hue and so on.
Well, I have 3 methods of control from my phone. 1. The method you described. 2. "Okay Google, Set bedroom lights to 50%" 3. I have a lock screen shortcut so no need to unlock my phone. I can also control from smartwatch in similar ways
Bleh, i hate this idea and I honestly hate smart phones too. Small, fiddly, annoying, have to arse around digging through multiple layers of apps/menus to get anything done. Having a physical button is vastly superior.
c'mon.... the next clive videos will be of how to hijack the super duper 128bit microcontroller with AI and get past the paid-per-month function "turn on"... it will be fun!!
Huh I just learnt something new, I thought dimmer switches were just variable resistors. Instead, they work more like analogue PWM. This explains why the one in my house made angry buzzing noises - until I removed it and replaced with with a normal switch so I could use LED bulbs in the room.
The very first theatre dimmers were variable resistors (rheostats) and got VERY hot in use.
Yeah after typing that reply it did cross my mind that rheostats probably get a tad warm, and probably wouldn't be safe to embed in the walls of someone's house.
Reminds me of my internship where the speed of a three phase motor in a printing press was changed by switching massive resistors in and out. There was an entire wall stacked with them. Mind you this was just around 4 years ago!
Sounds like an old machine. The resistor banks are less efficient, but I bet that machine lasts longer and gives less trouble than one with electronic motor drives.
Definitely. It was already giving a lot of trouble, but I'm pretty sure it'd been in service probably since before I was born.
Could a tungsten bulb be lit and dimmed with PWM in DC?
Yes it can.
Martin M. Some automobiles do that to dim the gauge lights. Mine is old and uses a big, fat rheostat.
Recently I had to buy LED bulbs for my dimmable living room lamp [getting more difficult to find the tungsten filament type] and whilst the new LED says "dimmable" the buzzing is too annoying.
Do you think you could please make a video showing us in practical layman's terms what happens if you use an LED bulb with a dimmer? I thought you'd made such a video and maybe you have, but I couldn't seem to find one.
Isn't that what he just did?
The Layman's terms as you put it... OK so a traditional dimmer will cause a standard LED bulb (non dimming type) to fail really quickly. Then when used on a LED bulb designed to be dimmed, the traditional dimmer switch would cause really bad flickering of the bulb. I have seen the results of both, and either effect is not good at all.
Lowest cost option is to use a LED dimmer switch (most of them have a trimming adjustment of some kind), and a quality dimming LED bulb. This is not a perfect solution but works well with no flicker since you "trim" the switch to allow full range of the dimmer.
The other option is to use a LED RF kit that has bulbs that use some sort of radio control, Bluetooth is the most popular one, since you can download an App that works with the bulbs. This allows you to control each bulb or groups of bulbs. Most of these offer all sorts of color options too. This sort of setup offers the most flexibility and can provide the best reduction in power consumption. Since you are not installing a dimmer switch in the wall that could potentially use more power then the LED bulbs would. With this setup you would only use a normal on/off switch. The main issue with this setup if the initial cost for everything, since the bulbs themselves are doing all the work. However since they are gaining popularity, the prices are dropping quickly. A year ago the Bluetooth bulbs were just over $40 for one, now you can find them for about $20.
I seen some bulbs that come with an RF remote control that allowed you to adjust the colour temperature and brightness and such, I thought they were good. I've been thinking of getting a couple of the LIFX bulbs but those are rather expensive.
Lachlant1984
You are absolutely correct there is all sorts of RF bulbs out there, the ones that come with their own remotes tend to be lower cost then the Bluetooth (form of RF signal) ones. The Bluetooth ones have the added benefit of not only having their own remotes (most of the time) but can also be controlled by certain things that uses Bluetooth like a tablet or smartphone for example.
Well, I went and had a fun adventure with a dimmer a while ago. First bulb I bought essentially strobed. It wasn't a flicker, it was outright strobing. That bulb apparently wasn't even a dimmable type, so I sort of chalked that up to me being stupid. Second bulb has been in the socket for about 2 years now, and it only lights up once the dimmer is about half way, but otherwise works fine. Hasn't failed yet.
My old dimmers were a rheostat style. Good old wire wrapped dimmer no electronics required
One day lighting circuits will be low voltage DC, with the bulbs containing no electronics but the LEDs. Elsewhere will be a fairly beefy AC/DC transformer and the wall plates will just do PWM of the whole system in the room. Spraying RF around the house to control lights feels too inelegant and error prone - I've used cheap RF doorbells before, they're not very reliable and like to randomly go off.
We have dimmable LED lights in some of our classrooms at work, and the wall switches are "clever" - press to turn on, press to turn off, hold to dim. Some of the bigger rooms have big switch panels with programmed presets to turn banks of lights on at set intensities. So we can press "1" to make the room full brightness, "3" for just the front lights, and so on.
With COB and filament technology low voltage high current DC is not a concern anymore. Mains AC can be rectified and fed into long chains of series LEDs controlled by a high-voltage buck regulator with PWM control. How to control? It's a matter of application. Choose from DMX, DALI, existing WiFi network. Something akin to homeplug ethernet might be interesting for domestic applications
Pretty much a noob at electricity, but how would you do this? Doesn't DC voltage drop over long distances with a decent amount of current? Seems like each light would be receiving differing amounts of voltage along the way through your house, so I dunno. Would you have the central transformer run all the wire at something like 12 volts and then have regulators at the base of each light?
Maybe 28 V.D.C. with up to 4 amps per circuit. Each wall plate can contain a small cheap buck regulator down to 12 V. or less for dimming.
I have lit a bar with about 15 meter of 12v ebay led strips, coupled with cheap pwm dimmers and a leftover computer power supply that is safely tucked away behind the audio rack. The whole thing cost about 25 euros.
Nice! I think one day houses will be wired with normal 110-220 VAC and some D.C. low voltage runs, maybe like USB type C that determine how much power is needed and set themselves to that level, if they can.
I too would like to see an update. I've replaced quite a few of the old bulbs with "smart" bulbs and I've noticed recently that there seems to be about a 2 year life span before thy start flickering, without any dimmer. So I'd guess the dimmer functionality you describe is built into the bulb? I had one replacement smart bulb that was on an occupancy sensor and it did as you described being very dim, so I had to keep that one as a fluorescent. I've had 3 different rooms so far (no dimmers) that smart bulbs have started flickering within a 2-4 year or so time frame. Seems there is a big difference in life span for smart bulbs vs regular LED bulbs, and certainly not what the manufacturer claims are
I've recently replaced a handful of LED bulbs within the last year that failed in 2 years or a little less, marginally longer than the 40 and 60 watt incandescents grew up with and loved and certainly much shorter life than the manufacturers claimed. The bulbs that failed seemingly early were used in enclosed fixtures meant for 60 watt incandescent, so heat build up could have been an issue, since LEDs prefer a cooler environment.
Idea: It seems many non dimmable LED lamps can be dimmed by a capacitor in series. Do you recommend this? Would it even be possible to use an adjustable capacitor to dim those LED lamps?
Thanks for the great video!
I made a video about that a while ago.
ua-cam.com/video/ISTB0ThzhOY/v-deo.html
I had this issue with a string of "dimmable" LED lights which flashed and had the sharp cut off as described in the video. The 12 LED bulbs only drew 48W on a 150W rated Lutron LED/CFL dimmer so I added one 60W incandescent light in an innocuous location on the string and the problem was solved with the full range of dimming and no cut off. Not exactly an elegant solution but the wife is happy.
I know Lutron have a device that replicates a resistive load without the need for using an incandescent lamp (which will blow in short order anyway). You'll need to terminate it in a suitable maintainable location, but it's a permanent fix.
Diac and Triac then onto Daleks. Run. Where is the Doctor when you need him? That leaves us looking for Sarah Jane Smith (Elisabeth Sladen, RIP) or Torchwood.
Clive how hard would it be to make a LED driver that was smart that can use PWM as a DIY project from the wall end of things and being able to
still work with an incandescent lamp if someone happened to stick one in and not blow up the driver?
OOPS foot in mouth. I was watching this as I was typing in and see that you covered it as I hit post. :p
I've used my RGB controllers to control tungsten lamps with PWM in the past. Notably in an oriental theme park to emulate lanterns.
@@bigclivedotcom I guess I was not thinking when I asked that and should of known the answer. One of those days.
How about a very small variac - I use a larger one for almost infinite control over LED lamps of almost any wattage.
make sure it is an ISOLATED variac. for safety.
Thank you, I've spent ages trying find info about this, very well presented. Cheers
Why tungsten lamp didn't flicker in camera when dimmed while the pwm frequency is only 120hz
Inertia
FYI: In North America we have PWM replacement wall-plate dimmers (for old phase angle dimmers). they work well with LED CFL and Incandescent bulbs. They can drive any load up to 150W, smoothly dimming from fully on to barely visible and cost only slightly more than the traditional units.
You deserve a SignPen sponsorship... 6:56PM 8/8/2017
Hi Clive, could you do an update on this subject.
I’ve recently changed my kitchen down lighters from halogen to dimmable led and they seem to work fine on the existing dimmer that was in the house when we moved in 20 years ago.
No buzzing or flickering from the lights or the wall plate.
It used to buzz a bit with the halogens when on full tilt 9 lamps @ 50w each.
I was actually surprised they worked having heard about issues with dimmable led.
Oh I wish I'd watched this before adding so many dimmers to my house.
Hi Clive,
I've recently purchased a dimmable LED from IKEA (LEDARE E27 1000lumen £8) and paired it up with a V-PRO-IR From Varilight (screwfix (1220J)£15.99) It works really well and you can program the dimmer to a minimum dimming level that stops the LED light from strobe-ing and the dimmer has programable leading edge, trailing edge or Digiflux? modes, trailing edge is the default and works best with the IKEA LED bulb, I know it's not a chinese £1 purchase but it works really well. If it didn't cost £8 I'd do a bigclive on the lamp, perhaps when it fails!
Clive you popped my electronics cherry! haha...got my first breadboard, jumpers and power supply today and got an LED to light at different voltages and an LED with a salvaged diode to light too! I know that's some really low level corny shit but ya gotta start somewhere, right. ...bought some little motor toys and junk at the dollar store for components and tear down to see how stuff works too. haven't been THIS "spastic enthused" about anything since I was WAY younger and dumb...when shiny things and motorcycles were new to me n made me drool like a retarded monkey in heat. it's all your fault that I now own helping hands, breadboard stuff and the page and a half of tinker toys on my eBay purchase list....n the growing pile of electrical disasters waiting to be disastered on the floor in the corner now...n it gets bigger EVERY time the mail comes haha. THANKS for that! lol
You can now get dimmable drivers that convert phase angle to PWM for backwards compatability. the market is slowly catching up to customer demands. it's like they were so busy making and selling LED bulbs they completely forgot how Joe blogs is going to actually drive the things.
VERY interesting video! I wish I saw this when working at a store selling among lots of things light bulbs. I never got the hang of which LED bulbs where dimmable and why. Thanks for showing and explaining how complex it is!
The IKEA Lunnom lights (the slightly more expensive ones with the brass colored base) work really well with traditional dimmers. I was really surprised by the dimming range, and they don't flicker at all. Perhaps a teardown of one of those would be fun!
Perhaps a return of the auto transformer?
It's kind of impressive that we have managed to make it difficult to dim a device that inherently has a linear(ish) voltage-to-lumen response.
I just have to say, I have learned more from your videos than i have from my high school before graduation. I've been watching for a while now and I must say I really enjoy learning, even if it is random from my point of view since I am not required to be on a specific topic now. once I accumulate the income, I plan on trying some of these circuits myself but that might take a bit of time. thank you for the knowledge.
which is why i put a 'ballast resistor' in parallel with the bulbs, just a pair of 3Kohm 10w ceramic power resistors in series is all it takes for 120V it also heps to lesser degree with CL rated dimmers in some cases
Thanks Clive, I appreciate the explanation.
Try this: Go to IKEA, bring a high speed camera (240FPS should do). Film the aisle of light bulbs. When you look back at the video you will see about half the bulbs flicker badly. If you look which bulbs flicker you will see that ALL the "dimmable" ones flicker and all the "non dimmable" are perfectly smooth....
The long term solution might be to switch to 12 volt dc wiring for domestic lighting. I recently installed half a dozen Bonlux T22 E14 ac/dc 12V-24V, 2W SES clear filament LED bulbs (from Amazon) advertised for "RV Camper Marine, Truck, Boat, Solar Power" in wall-lights a wooden gazebo. I didn't want to get involved with mains wiring regulations so everything is fed from a 12 volt dc PSU housed in the nearby garage. The lamps are really good but are far too bright and despite the fact that they're advertised as non-dimmable, I decided to have a go at dimming them. I tried them first on a variable voltage dc lab power supply and they dimmed nicely, cutting off completely at about 6 volts. Feeding them with a PWM signal didn't work (as expected, because of the internal smoothing capacitor), but I designed a variable PWM circuit using a 555 timer and fed that into a P-channel MOSFET with smoothing afterwards (as used in a buck regulator). It works perfectly. The waveforms all look good on an oscilloscope and nothing gets hot. It needs a bleed resistor across the output to cope with low loads and the pot needs to be logarithmic so that the dimming is not all bunched up at one end of the scale.
you know there are dimmable led bulbs, i just wonder personally, do they work properly with a non-synced pwm dimming circuit (constant pulsewidth modulation)?
i'm planning to make a digital dimmer myself, arduino nano, optocoupler, dual output transformer (+ - + to have a "separate" supply for the mosfet and arduino) and 3 fullbridge rectifiers (or 2 if i opt for an SSR, basically a TRIAC with an optocoupler)
so our lights need to be redone 100% where they are powered from the switch, then you will get led's that are nothing but a capacitor and maybe overcurrent protection? (high voltage PTC) and run from DC that was rectified and smoothed then have a high voltage buck constant current driver.
you dont need to worry about ac being more efficient over the wires unless you have more than 200W of light which at that point some sort of wired controller would be in the price range.
SO I SAY DC TO ALL MY DIMMEABLE LIGHTS
bulbs that are DC with pwm or fwm coming from the wall.
Are you saying that there may be LED bulbs that run purely on DC voltages and the dimmer uses PWM? Well, I suppose that's possible, what about 12 volt halogen lights? Does they run on 12 volts AC or 12 volts DC? If we were to change to DC powered lighting, it would need to be a complete full switchover for compatibility's sake otherwise you'd end up with hugs problems.
Halogen can run on either, they are basically a standard tungsten filament bulb filled with an inert gas. The L.E.D. only lights when reverse biased the DC circuit is fairly easy to control.
I'm surprised Clive didn't mention DC. It could eventually replace AC for home circuits and USB power delivery may play a large role.
Sure. If we were designing from scratch, all our lighting would be DC, and at a voltage most suitable for driving LED lights directly. And I expect to see that happen in the long term. But here in the UK we need solutions that are compatible with all the old wiring that's already installed in old buildings.
By the way, you also have to consider how you would control lights that are operated from more than one switch.
You seem to miss-understand, all the hardware fits into a standard socket the control is done via the start voltage and phase. although you could retrofit with dc lines to the lamp fixtures.
What would happen if you put in 2 bridge rec, and had one go directly to main's and the other feeds the second bridge rec??
I recently installed VARILIGHT V-PRO DIMMER SWITCHES with Philips Warm Glow Dimmable LED. They work well. The dimmers are programmable for various modes and come on with a gentle 'boost' . The Lamps have a 'lightpipe' to simulate filaments and have two sets of LEDs (warm and cool) the cool LEDs shut down to 'warm' the light at lower settings. They will dim very low without flicker.
maybe a stupid question, but could one build a compatible dimmer that just (e.g. via some sort of variable resistance, dropping or even filtered PWM to produce a fake sine wave from a rectified input for more fancy/smart/whatever solutions) lowers the voltage? or would the LED drivers try to boost (or buck less) that to the maximum LED voltage and randomly flicker? if so, maybe just ignore the fact those things have rectifiers expecting AC and supply them with (very fast) PWMed DC (so it still flickers, but with a few KHz-MHz instead of ~110Hz)?
Great video Clive, been dealing with this issue recently. Currently split between replacing the dimmer with switches and using dual white LED lamps with a remote control+hub... or just putting in the most efficient lamp type that works with a dimmer.
Before triacs were available the PA dimmer used a SCR across the + / - of a bridge rectifier ! ( I have one and it still works ! ) .. the colour changing LED lamps use PWM and a remote controller ... a small step to " beef up " the lamp driver to supply big LED room lights , using similar hand held controller ( then remove your room's triac PA unit , fitting a normal on / off switch ? ? ) this must be the way for the future ?
I've had LED lights for quite some time, starting with Sunflux. I recently moved to a new apartment with built-it dimmers, and I found out that Ikea has some pretty good dimmable LED bulbs at around 3.50 €, ranging from 200 lumen to 1000 lumen. They are even just about the same size as old filament bulbs, and has a pretty good spread. Well worth trying! ;-) @bigclivedotcom - any chance of you taking it apart, analyze and show the workings?
You are exactly right. The dimmer (as opposed to "dimmable circuitry") should be in the bulb or fixture, and receive commands via the power line. One simple command protocol is Blink'n'Dim. A short power interruption triggers gradual dimming or brightening, and another halts it. Technology to achieve this is described on ResponsivLED.com. As of this writing, no fixture manufacturer has embraced it. However, a 0-10V Blink'n'Dim Adapter is available on Amazon for fixtures that include 0-10V dimming capability.
Came here thinking I could finally get an answer to my question as I'm trying to design this very circuit.. 24VAC to 35V pwm LED .. so far so good with triac decoder circuit. But question I can't figure out is if the phase angle is low (say 10%) then how would there be enough RMS voltage to power 35V led using PWM it's full brightness at less time but still uses full power🤔
One of the (many) jobs of a LE compatible driver is to damp out the oscillations between the dimmer and emc filter capacitors. On most drivers this is achieved by having an additional series R+C after the bridge rectifier (usually 220nF and 330 Ohms)
What is not obvious is that this creates extra heat when used with a LE dimmer.
Example : 10 watt lamp full power no dimmer ( or TE dimmer) driver power loss =2.5 watts.
With TE dimmer at full power, driver power loss = 3.5 watts = 40% increase.
Why be bothered? well extra heat means it won't last as long, so my advice is never use LE dimmer with LED lighting. Use TE ( trailing Edge ) types such as Varilight Vpro
I'm a bit late to the party but since Halogens seem to have disappeared those dimmers I bought for a £1 in flockdown were discounted for a reason. Meh. I saw Great Scott made a little dimmer the other day. Not exactly easy. Do you still stand by using funky, remote-controlled bling LED's in 2022?
I have a dimmable LED in a bedside lamp where you touch the base to vary the light intensity. However the lamp acts differently when using LED lamps as against incandescent lamps.
When using LED, the light intensity is 0.5, 1, 0.25, Off ( so 4 touches of the base to cycle through)
When using incandescent , it is 0.25, 0.5, 1, Off
Any ideas why?
Would pulse-width modulation (fitted between the bridge rectifier and the LED itself) not be one possible option for dimming an LED light? As I understand it, LEDs easily tolerate rapid on-off switching, and some battery powered LED torches or head-lamps already use PWM to provide different brightness settings.
Another possibility: A miniature variac (directly rotated by the dimmer knob) fitted within the wall-plate, to adjust the AC voltage fed to the LED lamp. Of course a variac that small could only handle a few watts (maybe a few tens of watts at most), but LED lamps only use a few watts anyway, so that should work, should it not?
Those damn TRIAC dimmers caused me many a heartache as an AM radio (MW) fan... The harmonics from that nasty clipped AC would make any nearby AM radio spit out an annoying 120Hz BUZZ. The harmonics would affect up into the HF shortwave band and even to the 6m 50MHz band!
+bigclivedotcom - Thanks for addressing this. -- What about a low-voltage supply for lighting? Accent and Landscape lighting use (I think) 12v a/c? As the LED lamps are being pushed into replacing tungsten, any LED bulb could simply rectify the power, as most LED bulbs already do. Any dimmer could rectify, smooth and then PWM the power. It would certainly not happen overnight, but separate lighting and non-lighting wiring could become the new norm. Somebody is gonna have to rewrite a bunch of code and regulations.
Most new LED lights require a ELV (electronic low Voltage) noise reducing dimmer. If you are having issues using dimmers on LED lights save your self a lot of headaches and just purchase a Viribright LED dimmer switch. ELV 300VA 2 way or Single Pole. for like $16 on amazon
Here is some more information if anyone is interested.
You shouldn't use leading edge dimmers with any tipe of LEDs, even those with linear drivers which swich how many LEDs are in series. Voltage spike is so big that they can't react fast enough and even small capacitances arround the board make a big difference. (I wouldn't use leading edge dimmers anywhere thease days because some of them make so much noise they affect celphone, WiFi, Bluetoth...)
You can use trailing edge dimmers on most LED lamps with some kind of linear control as said in the video but the problem is not only flickering bacause of ON/OFF but zero cross detection too. LEDs are so fast you can see 0,5% jittering and with so much noise on the power lines these days zero cross detection is not that easy. (We set the minimum for this type of dimmer to 25%) so the jittering is not so visible, but it is still there if you look for it.)
There are many different options for dimming but they normaly start with dedicated LED power supplys at arround 25W and up, they are a bit more expensive but you can get a good brand for arround 20€/$ and they last for years. We mostly use 3 types of dimming: 1.Push button (for old instalations where wires are already in place and you can't use low voltage lines (Short press is ON/OFF, long press is dimming) 2. simple potentiometer normaly 100k ( thease type of power supply are the cheapest and the best in general, the probelem is you should have a cable directly from the lamp to the potentiometer at least 20cm away from mains power). 3. 1-10V (If you want to control more than one light at the time and you can easily add WiFi/ Bluetooth to this line) There are many others like DALI,DMX,KNX,Bluetooth, WiFi, LAN,... but for now I would advise to just use them for playing arround and not controll the whole house on it because one day it fails and when it does it takes a week to set up again. Leave those to companies, shops, entertaiment and people with too much money xD
A few years ago, I bought an expensive Philips LED bulb (similar to www.extremetech.com/electronics/128669-philips-new-100w-equivalent-led-bulb-runs-on-just-23w) and I will say that I can see why it was expensive. The colour of the light is the best of any LED lamp I've ever seen, it's beautifully dimmable, and it's lasted for ages without losing light output. It certainly beats any IKEA or Osram LED bulb I ever bought.
That isn't to say it was worth the £30-odd it cost, and I'll not get that back in power savings, but it is a really great bulb.
Resistive load vs. reactive load. The old filament lamps are resistors, where the phase angle between voltage and current is zero. But with reactive components as a load, such as capacitors, then the phase angle between voltage and current is no longer 0 degrees. God knows what the phase angle is because all lamps are different. It's a wonder to me that manufacturers have managed to make dimmers work with today's LED lamps. It's probably going to require some new standard for LED lamps and dimmers to fix this issue so that all LED lamps and dimmers present identical loads to one another. Remember the old X10 systems that Radio Shack sold long ago? Those things passed a high frequency signal (100 kHz?) through the power line that could talk to the receiver. These days they might use a wireless RF link instead. If that ever happens, we'll see the opposite of today's dilemma, where it's the old filament lamp that won't dim when used with the new LED-only dimmers. Just on/off, and that's it.
I have a cheap LED bulb with capacitor dropper and a simple switch with a neon bulb in parallel built in and when I turn the switch off the LED bulb dims down from 30W TL-D brightness to 1W fluorescent night light level, it has been operating like this for months and doesn't look like it's going to die anytime soon. So here's a thought: is it possible to use a neon indicator light in parallel with the dimmer to make it work on some LED bulbs?
Here in South Africa we have a company that has patented a so called "Universal Dimmer". I have bought one and it works really well. It will dim my non-dimmable 230VAC downlights without problems. Although I have noticed it doesn't work on all brands 100%. Apparently the dimmer is only compatible with constant voltage and constant current drivers. Here is the link: www.caelus.co.za/inc/pdf/Understanding_alldimmer_2015.pdf & www.caelus.co.za/inc/pdf/alldimmer_web.pdf
I use a dimmer made by LightwaveRF which at around £40 each isn't cheap and if you use 'normal' led bulbs they flash but LightwaveRF say to use Megaman LED bulbs which Megaman is something to do with LightwaveRF and those bulbs work fine with the dimmer but once again the bulbs aren't cheap either. I think all in all I spent almost £70'ish just for a straight forward dimmer and 3 GU10 LED Bulbs. I wouldn't of normally gone for this but the dimmer ties in to my home automation stuff so I wasn't to fussed.
The end of your clip? You are holding 2 lamps, an LED and a filament type. The LED light in your left hand is one of those LED strings which just runs on main, no circuitry at all. That one could be dimmed if we would have a switch with extra leds in it. The leds would cause a voltage drop, which will lessen the current. So we get a switch which lights up (a dimmer), and the main light would dim as well. On the other hand, the LED light in your left hand does flicker to a point where it gets very annoying. (the main reason for my idea to do it this way is so that we are not throwing away any power loss and have a true dimming). Of course I understand this dimmer will be fixed for the led light because the current must be equal. But hey, it is just an idea. I see many other possibilities like using a dc to dc controller for instance.
What does actually happen if you REALLY run LED lamps with various kind of dimmers (with resistive/capacitive/switch mode power supply circuits inside)?
I understand it in theoretical level but I really want to know what actually happens to them.
p.s. And CF lamps too!
As far as I know, there is a 0-10V or 0-5V system in use. Probably just plain potentiometer using referance voltage from the LED driver.
But that's not the classic LED bulb, I would expect a rather integrated system where the knob only goes to the lamp, and do not have mains power going via it.
Probably worthy a review, but likely not the cheapest!
If they're going to develop new wallplates (that would be signalling the lamps over power or via RF), then instead of again switching all the LEDs on and off (albeit quicker this time, using high-frequency pulse width modulation), would it not make more sense to design the lamps compatible with a clean-slate dimmer-to-lamp protocol so that these "dimming 2.0"-compatible lamps would consist of multiple LEDs, and would only drive some of their LEDs, depending on what the dimming 2.0 protocol tells them?
Don't you have the flickering problem with florescence lamps with a traditional ballast thingy?
But the main problem I see here is that we still use that damn AC from the last century/millenium...
The problem with this shit is that you need a variable power supply, for DC-DC it's not that hard to do, you "just" need a variable buck/boost converter...
So in theory, it's completely possible to make such a thing. The problem I see:
Is it possible to make it small enough (and with high enough build quality) that it fits inside the wall?
Or would it be just too big if you want to make a decent voltage regulating device (well, that's what Dimmers to, if in a rather shitty way)...
I personally like to use thoose cheap COB led from china, like ebay or aliexpress, with a variable dc-dc step down converter with variable current limit (the LEDs are about 0.5€, and the dc-dc converter arround 2€... quite cheap actually). If you use the current limit feature just below full power, you can effectively dimm the light with little to no noise... and no flickering that i could notice.... The problem is to design that to be able to control it from the wall while using standard lights... How about the led's power, thoose who don't know about it would probably just pump too much current trough the led and burn it... And you'd need to have an ammeter somewhere to control the top amp if the dc-dc limit is over the LED's... That would be too complicated to normal ppl arround...
Since LED lamps seem to have quite a few individual LEDs, why not turn on and off banks (or even individual) of LEDs? For very low light level, turn on six LEDs, and ramp up six at a time to 72. That would give 12 steps on a 72 LED chip.
Instead of PWM to control all LEDs in the light, would it be possible to use the sine wave to turn a percentage of LEDs on? For example, at 100% all LEDs are on, and when the dimmer is at 50% then only 40% of the LEDs are on (I'm assuming it's not a one to one ration for power in to what the human sees). That way, hardly any flicker as it's no longer PWM controlled...
One thing that maybe of interest Clive is ZEGALED a USA company distributing product sourced from 'Sunfor' in China. The bottom line here is long persistence LEDs by the use or rare earth materials which in theory massively reduce flicker.
I have had no success in testing these. Do you have the contacts to get some? The LEDs themselves are called REAC LEDs and are primary intended for ac led solutions ( bridge and current limited LED string..no large caps).
Jerry
Since you have LED lamps with and without the drivers, that makes it a mess to try and work around it directly from the supply.
As you said, if it has a smoothing cap, you can't really do anything, since the buck driver would just work harder to output.
So isn't the problem coming from more of a "missing standard" on what an LED lamps contain?
So making a matching pair of dimmers and dimmable LED lamps, would work the best?
I am using 3 brightness level LED globes, controlled by switching them on/off multiple times to get a dimmer light output. So at the first on state, they are at full brightness & each following power off/on cycle reduces the brightness level (twice in total), then they are back at full brightness at the third cycle! The globes did cost a little bit extra, but it is worth it!
This is a pretty good explanation, however is is somewhat "Clive-centric". Here in Australia, the use of capacitive droppers is pretty rare, as those lamps don't comply with EMC or power factor standards. Also, the use of PWM is not the easiest way to control LED brightness, nor is it the way that dimmable lamps are controlled. Modern chips adjust the output current, and they internally handle power factor as well. A single-chip buck with current control and PFC is extremely cheap with low component count.
I have a new Philips R7S LED Dimmable working perfectly with a Legrand wall Dimmer. I have tried a Philips and other branded G9 dimmable with ceiling fan light but it doesn't work properly
How do Christmas light fading, dining, flashing, strobing, chasing circuits achieve the resulting effects?
According to the latest technology I've seen, the dimmer module varies frequency, the supply to the LED is rectified to DC so the LED does not care about the frequency but.........
Their are two (glass or plastic )envelopes around the LEDs with a gap for a substance which becomes less opaque (more transparent) at higher frequency controlled by the on board electronics.
Fun fact: Leading Edge was a computer company that made 386, 486, and Pentium systems in the late 1980s and early 1990s. They had a few modems as well.
1. Thank you!
2. Damn, I guess we'll just have to replace the dimmer with a regular light switch... :/
This is why commerial installations used voltage or current controlled lamps, running at 24 to 50 volts. They are connected to the mains via dedicated drivers and power supplies. The drivers themselves are dimmed using DMX, DALI or 1 to 10 Volt signals. One driver can control a numerical of leds, and a suitable PSU could feed a number of such drivers. Essentially the lighting is a low voltage installation.
Direct mains dimmable Leds are for existing installations where rewiring isn't practical.
Wonder if you can get away with rewiring your house to where the lights go off at say...a 12 volt power supply, running 12V LED lights off it, and just putting PWM circuits where you want dimmable switches.
At least if there's a blowout, you could have light off a car battery or similar.
Been using Dimmers extremely sparingly with CFL bulbs. Mostly because of ahem. it's supposedly rather dangerous and I tell people who use CFL's with dimmers. pop the dimmer all the way on and leave it there. (and many of these are in enclosed ceiling lamps smh ahem anyway. Hadn't thought about LED's yet. Some of the LED c7 bulbs I've stuck in night lights designed for incandescents light up even with the power off. So I'd imagine trying to dim them would be complicated since they light up with a very low voltage.
Clive, Every year I put LEDs outside my mates house and we can dim the LED's using an 3 or 8 channel control board comprising of a triac, A control chip, A few odd components and the input from the computer... Yes we do the sound to light for christmas but we dont use the american stuff. We have full control of the dimming of the LED's either strings or the RGB strips.
Who knew LED lamps were so interesting?That probably comes down to a thoughtful producer / narrator & the inherent complexity of LED systems.
White LEDS are actually ultraviolet LEDs with a phosphor layer that converts the ultraviolet radiation into visible light. The phosphors have an afterglow similar to the afterglow of an incandescent lamp filament, greatly reducing the flicker when driven with 50-60 Hz mains power.
All dimmable lights strobe. All of them :( please correct me if I'm wrong, I will be very happy finding one. I have tried nearly every make of 'dimmable' bulb and they all flicker, even the expensive Philips and Osram ones, some worse then others. Doesn't matter if your use a dimmer or not, or a traditional dimmer or a trail edge dimmer, even in a straight on off switch like a lamp they seem to strobe/flicker when tested on a slow record. The quick test I did was slow motion video on the iPhone where you can see the strobing on all dimmable leds. Even get strobing on all hallogens (they can all dim). However, a few straight non dimmable leds I tested (like both Philips core pro 11 and 13 watts were completely stable). I'm dreading to think that no dimmable leds that don't strobe even exist. Even if my eyes can't see the dimming, and only in very slow motion you notice it, I'm sure my migraines come from them. Has anyone else tried this iPhone test? I am completely wrong with how I'm testing or am I right and all bulb manufacturers offering dimmable bulbs ruining our health?