From what I understand, that strange resistor code (EIA-96) is used for higher accuracy (1% tolerance) resistors. So the value of that one will be 15.0 Ohms (+/- 0.15 Ohms).
This is a pretty nice implementation of LED retrofit bulbs. At first glance, it appears these bulbs were well-designed by someone with at least a smattering of electrical engineering knowledge, which is a refreshing change! I've used several brands; one of which was pushing the chips right on the cusp of maximum tolerances at 12v. Which might be "fine" in a theoretical world, but those of us with moderate knowledge of 12v automotive charging systems know that the bulbs are typically seeing around 13.8v when the engine is running (read: alternator is charging). Lifespan ranged from a few hours to a few months before individual chips began flickering or getting the Black Dot Of Death. Another brand that I've been using for several years now began with a diode, resistor, and single chip, they worked really well and I have some with over 6 years' use (still working, but getting a little dim), but the company continues to improve their design. The latest version uses a glass envelope with the exact same dimensions as the incandescent bulb they're replacing (for a perfect fit) and tiny COBs. Quite reliable and very bright, without abusing the COB. I actually have to turn the dash dimmer down quite a bit for comfortable night viewing, which is fine with me because I'm under-driving the bulbs and thereby increasing their lifespan considerably.
I have had 90% of my LEDs failing after few months on my different motorcycles and nobody could explain why. The COBs seem to have a longer lifespan (more months to a year). I am glad I am not the only one, everybody I have asked to just answered "Don't buy cheap chinese rubbish". Actually even some some reputable brands' have failed miserably.
Would you mind sharing what that last mentioned brand is? I've been trying to find decent LED replacements for my map/dome lights. Gave "lasfit" a try and while they seem well made they unfortunately don't have a warm white option and the amber ones I settled on are a bit too warm.
@@chongtak I believe that the charging circuit on cars and motorbikes produces noisy DC. There more electric motors and solenoids in modern machinery, plus a high voltage powering the spark plugs. Transistorised ignition is better than the old Kettering type, but I am still not convinced it is less electrically polluting.
@@chongtak The best LED retrofits I've ever bought were Philips Vision 1156 brake bulbs, for my Scion XB. Got them in December 2016 and they're still going. Like another person said I think motorcycles tend to produce "dirty" power. As great as LEDs are, they're unfortunately not very tolerant of voltage spikes. There's no way around it without building some switching regulator into them which would drive up their cost.
The EIA-96 coded resistors are 1%, so they would require 3+1 digits to print the actual value. Using a lookup index in the E96 series only requires two digits and a multiplier character. I guess it's more legible to print 3 characters on the smaller SMD resistors than 4 digits. This resistor just happened to be 15(.0) ohms, making the last digit seem insignificant, especially with 15Ω also being in the E24 series - but if they had needed a 14.7-ohm resistor instead, 14R7 might've been pretty cramped and not condensable. I finally had to decode a handful of those EIA-96-coded resistors, so I wrote a script to do the lookup for me. The formula is straightforward, but still requires lookup or a calculator unless you've memorized the whole E96 series: two digits for the position in the E96 series (01-96, giving a value between 100 and 976), then a letter for decimal multiplier (A-F for 0-5 zeroes, and X-Z for x0.1-x0.001 -- except that sometimes B=H, X=S, or Y=R). The hard part was writing the code to give me the nearest EIA-96 code for any resistance I give it.
Considering the limited availability of E96 series I do my designs in all E24 1%. Usually when I call the vendors they got them a plenty and they are the cheapest. If I choose a non E24 then they tell me sure mate but we'll have to run a batch just for you. So two months. If for some reason I need a value between an E24 number I just parallel or series two resistors.
Nice and simple, and I like both AMS1117 as a CCS and the use of a FULL BRIDGE RECTIFIER for ensuring polarity regardless of the way you put the bulb in. Simple is better than complex, beautiful is better than ugly, readability counts, blah blah.
The very old LM1117 was designed long ago by National Semi (now a part of TI), a better version of the LM317. The latter has a much higher dropout voltage (≥ 3.0V) than does the former (≥ 1.2V). It's output voltage formula is (1+R2/R1)*1.25V, or (1+22/15)*1.25V = 3.1V (nom). There is a small current coming out of the ADJ pin (60uA nom) that can be ignored if the load current is set high enough, making the circuit look like a current sink to the load connected to its input pin. You just have to make sure that the voltage at the last LED cathode stays above the dropout voltage, or about 3.9V. Since you measure the LED total voltage of 8V, it means that the circuit will drop out of regulation when the input voltage drops below 8V + 3.9V + 2*Vdiode, where Vdiode is the voltage drop on each of the FWB diodes, probably about 0.7V each. I.e., when you start the car and the car's voltage drops below about 13.3V, the current sink will not function properly. But when the car is running and Vin is above that, you're good. The LM1117 in the SOT-223 package is dirt cheap, which is why it is used. A good test of the lamp, Clive, would be to connect it to a lab supply and lower the voltage to it until you see the light start to dim. Personally, I think the dropout voltage of this lamp is too high to be reliable enough for automobile usage.
So basically they could remove the 22 ohm resistor to let it regulate even at lower input voltages. So why have the resistor at all? It's probably to reduce the 1117's dissipation at higher input voltages. A resistor between the regulator's in and out pins could solve that problem, leading to an overall improved design with the same BOM.
I got these around 5 years ago in cool and warm white to use in my car. Didn't know they were still available since they look quite expensive to produce with the glass tube.
These would be really handy for LED conversions on older, small capacity motorbikes for a couple of reasons. One is they will often be running either dirty halfwave rectified and un-regulated/poorly regulated charging systems or even straight-up unregulated single phase AC for the lighting. The other is the indicator dash repeater bulbs often run the DC in opposite polarity depending on which indicator you're using. Even incandescant bulbs struggle sometimes and cascade bulb failures are reasonably common. These seem like they would cope with all of that madness without too much stress
Leds are great, for old 1980's bikes with 6v electrical systems and a tiny battery than can't really even run the indicators and the brake light even when everything is brand new.
Forget the circuit... This is the style of LED I've been saying drop-in automotive LEDs should be! Actually keep the light source in the original location within the fixture so the light is properly reflected. All we need now is for this to work its way to the bigger lamps!
I like that this has a filament that is starting to mimic the same position as a traditional bulb. That's essential if your lights are going to focus properly. Would love to know how bright this is compared to the 5w wedge bulb it replaces.
I was reading the datasheet as you were explaining the circuit. The part that says, "Oh, you shouldn't need to stick a diode on the output because we've got that mostly covered" made me chuckle a bit. They don't describe current regulation _per se,_ but they do mention a constant current between output and adjust pins if there's a resistor connecting them. Very clever use of this LDO regulator, and you don't need a big inductor like with an AL8860.
It's a standard use for a voltage regulator. You could do it with an old '7805 but the later LM117-style and lower dropout regulators are far better suited to it. As the 1.25V is derived from a bandgap reference it's very stable and makes a good and cheap voltage reference.
@@Graham_Langley It might be a common use, but most hobbyists like myself are probably not familar with it... being a voltage regulator and not a current regulator will limit searches for such circuits 😺 - when I saw it, I was from "what the..." to "oh, that is smart" in a few seconds, but I never seen it before and that's why I love Clive's videos. A nice source for such little tidbits without reading boring data sheets all day.
Nice little lamp! I might have to get some of these for my step-dad's truck...and excellent replacement bulb for his old filament lamps when they finally go bad.
What a nice design. I have this exact style of lamp in cold white as a position light in my car. Looks neat and matches the xenon bulbs. Good to know that they don't run directly on the supply voltage.
I wonder if the reason for the rectifier is to avoid damaging the voltage regulator with reverse polarity. In any case, it's gratifying to see manufacturers using a rectifier in this way. As you say, it is quite easy to reverse the device to make it work, not so easy when the lamp has a bayonet cap! My car (a Ford) has positive shell and negative pin, the opposite of most vehicles.
Look in the data sheet of the LM317 - it has a number of "unusual" applications of an adjustable voltage regulator. One of them happens to be a constant current source, but there are a number of others
That's a old school way of turning a voltage regulator in to a constant current supply. Used to do this back in the 80's to charge nicads. Nice to see some old ideas still being used.
It's a nice bulb replacement for some vehicle interior lighting where the circuit board style ones won't fit, for example 2005-2015 volvo dome lights. Plus it's current regulated, so the alternator is less likely to kill it.
I have just torn down an empty 50ml Cetraben emollient pump dispenser and it might be worth considering for a short mechanical video. It has 9 components, excluding the contents & label and is rather clever. The magic happens via the small hole in the bottom!
No CAN bus resistor, so it will set a fault code on vehicles that monitor the continuity of the lamps continuously. Simple to fix, a 220R resistor across the pins will allow enough current to flow.
The trick of using the adjustable regulator as a constant current source comes directly from the LM317 datasheet - it actually has a number of "unusual" application circuits in it that can be quite handy. I always lump the LM317 in with the 780x regulators in my head.
@@willthecat3861 I got some AMS1117-3.3 to mess around with some tiny adapter boards, and added a resistor as here, resulting in a LED current source with a similar overall forward drop to the 317 circuit.
For automotive applications, you'd want to use voltage regulators with at least 40V max rating so they don't immediately blow up on the slightest alternator-battery hiccup.
That's standard design practice, but any remotely modern vehicle won't produce those voltages. "Load dump" spikes were a problem with slow regulators, mechanical voltage regulators and early electronic regulators.
@@1djbecker Although many newer cars (where "newer" can easily be 10 years old or more) use switching supplies for the 12V, isn't inductive spikes from switching loads still a thing?
Reminds me of some years ago using LM317 to CC drive =>1W LASER diodes. Popping balloons, lighting matches or candles and even a few cigars... Fun times!
That trick of using an adjustable voltage regulator as a constant current source comes from the datasheet of the LM317. It has a bunch of "unusual" application circuits in it - the LM317 (or any adjustable voltage regulator) can be used in a number of non-obvious ways!
@@gorak9000 If you're a fan of "unusual applications" of company ICs, search for (my favorite) "555 based solar charge controller" for almost everyone's favorite IC adapted to a seemingly unrelated function.
It's nice to see constant current regulation, on 12v LED car lamps. It's so much better than just a resistor, for the variable voltage 11v-15v in a car. I guess the circuit would also of worked, if used as a voltage regulator, with a current limiting resistor for the LEDs. If the regulator was set close to the total forward voltage of the LEDs, then the current limiting resistor could be small and low value.
And it's more foolproof - the full-wave bridge rectifier provides reverse polarity protection. I would like to know if this was meant to be a replacement lamp for instrument clusters, behind the dashboard. No more burned out lights hindering the driver! 😊
I got some 39mm Festoon LED Car Bulbs and was surprised they work whichever way you insert them. So they must have a bridge rectifier. I haven't tried to take one apart to see if they are current regulated or just a resistor. Actually it might well be that all car bulbs are current regulated so the brightness stays constant regardless of the voltage on the nominal 12V bus which can probably vary quite a bit.
Some are some are not. The ones that run on anywhere from 10v - 30v must be. I measured some that were using 500ma on 12v and 250ma on 24v . So as you increase the voltage they reduce the current they use, if you get below 7v they start flashing like a strobe light.
For automotive use the nominal voltage is 13.8 volts, but should be expected to vary from 9.5 (while starter is cranking) up to 15.75 (charging a low battery with very cold temperature). Ideally one should design for possibly nearly 24v peak to peak AC on top of the DC voltage.
@@chrishart8548 If the current goes down when you increase the voltage they must have a switching converter. Very fancy as well as relatively unreliable.
If you are here, in the New World, you can check out the Sylvania ZEVO brand of white LED mini lamps, for automotive interiors fixtures. It is also non-polarized (just so the old folks don't wonder why the dang thing won't work, when you plug it in... when a good 'normal' light bulb always would.) Anyhow the OEM is DE3175.
i love these things. They look like they were DIY made. But there's a machine somewhere out there that just holds these tiny little LED glowsticks and solders them together in this funny shape.
These look like a good fit for interior car light. The filament ones burn often. I wonder what the current through each LED is? Not 82mA for sure. With only 8V voltage drop across the LEDs, they are surely in series/parallel configuration. Longevity will depend on the current through each LED.
Interestingly, 8V + 1.25V + 1.8V + 1.5V = 12.55V, plus there is some drop-out across the regulator, so the regulator isn't really cutting in until the supply voltage is over ~13V.
I have a version with two pins, rectangle filaments and dipped into a sillicon rubbery type of solution to form the 'bulb'. It runs on 12V and polarity doesn't matter.
These might work a lot better for older cars that use filament bulbs. Many o the LED lights if you buy them in the UK saw they are not indented for road use. 🤦♂😂 A lot more going on than I expected 2x👍
Some of the more modern cars detect if a bulb has "blown" and report a fault if LED bulbs are used to replace filament bulbs, so unless your car is designed to use LED light bulbs you may well end up with a fault being reported when you replace a filament bulb with an LED bulb. The fix used to be to fit a large wattage resistor parallel with the LED bulb to mimic the current drawn by the original filament bulb to avoid the error message of a blown bulb being displayed. I'm not sure what the latest cars make of the user replacing the original bulbs with LED bulbs, though. KW.
@GetCarterCarPark ... I'm not sure that it's a 'current draw' that is used to check for blown bulbs ... I put one early LED in my '95 truck (combined stop/turn signal) without the extra resistor ... The turn(/stop) on that side started to trip the cruise control ...I don't know if it was sensing the 12v when the brake light was on, or if it was using the bulb as a pull-down resistor ... I wondered if a high value resistor in parallel would have worked - but never investigated ... I know that the high brake light had to run off the switch on the master cylinder (which is PRE- flasher?)
@@jayherde0 On a 2000 Accord there is indeed individual current sensing for both of the main brake lights, I don't know what the threshold is. What happened with your truck doesn't make much sense but I can think of one remote possibility. If the bulb has a non electrically reversible base there could be a capacitor inside the LED module. When the turn signal turns off the lamp would be reconnected to the brake switch and the charged capacitor would provide voltage there for an instant before the high brake light would discharge it. The cruise module could see this blip and interpret it as you tapping the brake pedal. It just doesn't seem very likely that all those conditions would be true.
Hi Clive - At what volts do the LED'S start to light? As I have found Running the Lamps on 10v5 they do not get as hot and consume less current and make great work bench emergency lights run from a 18650 charger VV booster and can run for a couple of night with out charge.
There are some comments about it mimicking the filament for proper "light bouncing", but to me it looks far too big "filament" in this one compared to regular W5W bulbs. It is a nice design tho, with proper current regulation.
Are these bulbs available for a lower input voltage? Because that light would be great for pinball machines, in the spaces where the bulbs are visible on the playfield. Older pinball machines often use 6,3 V for the light's. Some AC and some DC.
I wonder if the filaments being different brightnesses is to allow them to be used in combined stop/tail or stop/park replacements where you have a dimmer red all the time at night and a brighter red when braking. Obviously not implemented here but maybe they have other versions
I've never been able to grasp transistor theory, lol and I still don't. Digital...easy as can be. Analog kicks my ass but I'm going to keep watching your presentations until I get it. Thanks for your wonderful presentations.
It would be good to see how it stands up vibration and voltages around 13-14v. I have gone back to standard old halogen globes in our cars as the leds lately dont even out live the bulbs......
A similar circuit is used by the 12 Volt , warm white ( G4 pin base ) lamps , sold in many shops ... the regulator is handy , should the voltage rise ( 14 Volts ? ) , the current DROPS to give a constant brightness ( and vice - versa down to about 10 Volts ) .... the BIG problem with LED bulbs in cars , is that they use MUCH less current than filament bulbs , sometimes confusing the car's electronics ( says : bulb blown etc ... ) , VERY handy lamps in case of power cuts or camping , BTW .... DAVE™ 🛑
Spring point meter probes are great for keeping probes on a contact point. As with a pair of alligator clips on a board holder. One for the board and one for contact point. The sun is setting so the drinks are poured.
Using the diode bridge isn't really less efficient since the regulator is a linear one. If the diodes weren't there the regulator would have to dissipate more power.
I was thinking more along the lines of potentially using four sets of LEDs in series for greater efficiency. But the three sets do allow a wider voltage range.
@demef758 The infamous 117 crap. Have experienced dying expansive circuits when / because the THERMAL capacity of the IC itself is tiny small and the underlying cooling area did not dissipated the heat quickly or was too small. The issue happend to me on professionally made units and home made projects too. The dead of the 177 caused expansive losses when it burned ALL the powered circuits on the pcb & subsequently the LED displays. The thermal over protection DID NOT WORK, never. No shutdown was performed. It shut cut off the load entirely when it reaches the max current /max temp.
Nice, worm "tungsten" light. Chinese 1117 copy of TI regulators aren't exactly voltage regulators, but more like 317, and though still very popular are rather outdated - not low enough voltage drop and a rather high voltage reference for current regulation.
Lovely video and lamp! If possible, I would love a link for this or a similar lamp of such high quality. I have not seen this little marvel on the webz before. Most lamps with this socket are pure garbage.
Many thanks. Learned about using a rectifier for DC polarity determination. The light given off seemed very modest. Where in a vehicle would this be used?
Would be interesting to see the dye package On a side note, the 3voloution air fresheners you covered previously, now bost new smart programming, personally the look exactly the same with zero changes to the outside, maybe worth a revisit?
Nice smart design - I like it but wonder how we got from a bit of resistance wire in a glass envelope to a electronic module and ceramic LED strings 😂 and I bet it's cheaper to make!
It's like how now it's cheaper to have backlit TFT LCDs than analogue gauges so the cheap cars are all TFT and the expensive ones have analogue gauges. Which would have seemed insane 10-20 years ago.
Hi Clive Just something which may or may not be anything to do with this type of bulb, since buying my Vauxhall Grandland every so often whenever I put the right turn indicator on I get a fault indicator and my incarinfo tells me to take my car to the nearest garage, I have done this and they are not sure what the problem is but they think that on some cars who have halogens and not LED's (this could be the other way round) could be the cause ,but as I told them why only on the right turn
If the car is designed for regular bulbs but an LED is installed the lower current draw could make it think the bulb is burned out. But if an infotainment is saying to take the car for servicing just because of a burnt bulb it doesn't seem like a very good system.
V. nice reverse engineering job - these things are tiny! Clive do you think the bulb was filled with heat conducting gas to help the cooling? A lot of the glass LED filament bulbs are filled with helium , which transfers heat from the filament far better than air would. That's how they get away with using no heat sink on the higher wattage specimens..
I think they are even more in series than that. As most LEDs have a power drop around 1.5-2 V, I guess that they are even partly parallel inside the units themselves. Clive, please enlighten us.
Since Tesla is currently a bit over 12 V, and will move to 48 V for its low voltage this year (the Cybertruck will be the first), would this work for about 50 VDC? Something similar would work, at least.
It would be nice to know the ebay search terms for those lights. They look like they might last a bot longer than 501's tungsten or LED bilbs thay overheat and birn out in a few weeks.
From what I understand, that strange resistor code (EIA-96) is used for higher accuracy (1% tolerance) resistors. So the value of that one will be 15.0 Ohms (+/- 0.15 Ohms).
I seem to recall reading something about that.
I concur, use the. Use them often for stage lighting moving head units
Yes the alpha numeric gives you much more info in a print you can read.
Yest, Clyde isn't a real engineer so he doesn't really understand what's he looking at. 18X = 15 Ohms
@@molkhal Closer than many of the "real" ones I work with.
This is a pretty nice implementation of LED retrofit bulbs. At first glance, it appears these bulbs were well-designed by someone with at least a smattering of electrical engineering knowledge, which is a refreshing change!
I've used several brands; one of which was pushing the chips right on the cusp of maximum tolerances at 12v. Which might be "fine" in a theoretical world, but those of us with moderate knowledge of 12v automotive charging systems know that the bulbs are typically seeing around 13.8v when the engine is running (read: alternator is charging). Lifespan ranged from a few hours to a few months before individual chips began flickering or getting the Black Dot Of Death.
Another brand that I've been using for several years now began with a diode, resistor, and single chip, they worked really well and I have some with over 6 years' use (still working, but getting a little dim), but the company continues to improve their design. The latest version uses a glass envelope with the exact same dimensions as the incandescent bulb they're replacing (for a perfect fit) and tiny COBs. Quite reliable and very bright, without abusing the COB. I actually have to turn the dash dimmer down quite a bit for comfortable night viewing, which is fine with me because I'm under-driving the bulbs and thereby increasing their lifespan considerably.
I have had 90% of my LEDs failing after few months on my different motorcycles and nobody could explain why. The COBs seem to have a longer lifespan (more months to a year). I am glad I am not the only one, everybody I have asked to just answered "Don't buy cheap chinese rubbish". Actually even some some reputable brands' have failed miserably.
Would you mind sharing what that last mentioned brand is? I've been trying to find decent LED replacements for my map/dome lights. Gave "lasfit" a try and while they seem well made they unfortunately don't have a warm white option and the amber ones I settled on are a bit too warm.
@@chongtak I believe that the charging circuit on cars and motorbikes produces noisy DC. There more electric motors and solenoids in modern machinery, plus a high voltage powering the spark plugs. Transistorised ignition is better than the old Kettering type, but I am still not convinced it is less electrically polluting.
@@chongtak The best LED retrofits I've ever bought were Philips Vision 1156 brake bulbs, for my Scion XB. Got them in December 2016 and they're still going.
Like another person said I think motorcycles tend to produce "dirty" power. As great as LEDs are, they're unfortunately not very tolerant of voltage spikes. There's no way around it without building some switching regulator into them which would drive up their cost.
The EIA-96 coded resistors are 1%, so they would require 3+1 digits to print the actual value. Using a lookup index in the E96 series only requires two digits and a multiplier character. I guess it's more legible to print 3 characters on the smaller SMD resistors than 4 digits. This resistor just happened to be 15(.0) ohms, making the last digit seem insignificant, especially with 15Ω also being in the E24 series - but if they had needed a 14.7-ohm resistor instead, 14R7 might've been pretty cramped and not condensable.
I finally had to decode a handful of those EIA-96-coded resistors, so I wrote a script to do the lookup for me. The formula is straightforward, but still requires lookup or a calculator unless you've memorized the whole E96 series: two digits for the position in the E96 series (01-96, giving a value between 100 and 976), then a letter for decimal multiplier (A-F for 0-5 zeroes, and X-Z for x0.1-x0.001 -- except that sometimes B=H, X=S, or Y=R).
The hard part was writing the code to give me the nearest EIA-96 code for any resistance I give it.
Considering the limited availability of E96 series I do my designs in all E24 1%. Usually when I call the vendors they got them a plenty and they are the cheapest. If I choose a non E24 then they tell me sure mate but we'll have to run a batch just for you. So two months.
If for some reason I need a value between an E24 number I just parallel or series two resistors.
@@kthwkr decent suppliers have E96 1% in stock nowadays. It's 0.1% and better where you'd better stick with E24
Very very neat little Vehicle 921 Dome Light Bulb
Nice and simple, and I like both AMS1117 as a CCS and the use of a FULL BRIDGE RECTIFIER for ensuring polarity regardless of the way you put the bulb in. Simple is better than complex, beautiful is better than ugly, readability counts, blah blah.
you cant beat a good full bridge rectifier . 🤣🤣
@@dcallan812
only that it might suck 1.4 … 2V, depending on the current. That’s a lot with a 12V supply.
Ok, resistor & regulator drop more.
@@fromgermany271 it would suck lots. But it was a joke on electrobooms channel. . 👍👍
@@fromgermany271it's a lot less than the near 4 watts used by the #194 it replaces.
@@dcallan812 Shurely, that's copyrighted by someone else.....😉
The very old LM1117 was designed long ago by National Semi (now a part of TI), a better version of the LM317. The latter has a much higher dropout voltage (≥ 3.0V) than does the former (≥ 1.2V). It's output voltage formula is (1+R2/R1)*1.25V, or (1+22/15)*1.25V = 3.1V (nom). There is a small current coming out of the ADJ pin (60uA nom) that can be ignored if the load current is set high enough, making the circuit look like a current sink to the load connected to its input pin. You just have to make sure that the voltage at the last LED cathode stays above the dropout voltage, or about 3.9V. Since you measure the LED total voltage of 8V, it means that the circuit will drop out of regulation when the input voltage drops below 8V + 3.9V + 2*Vdiode, where Vdiode is the voltage drop on each of the FWB diodes, probably about 0.7V each. I.e., when you start the car and the car's voltage drops below about 13.3V, the current sink will not function properly. But when the car is running and Vin is above that, you're good. The LM1117 in the SOT-223 package is dirt cheap, which is why it is used.
A good test of the lamp, Clive, would be to connect it to a lab supply and lower the voltage to it until you see the light start to dim. Personally, I think the dropout voltage of this lamp is too high to be reliable enough for automobile usage.
So basically they could remove the 22 ohm resistor to let it regulate even at lower input voltages. So why have the resistor at all? It's probably to reduce the 1117's dissipation at higher input voltages. A resistor between the regulator's in and out pins could solve that problem, leading to an overall improved design with the same BOM.
I got these around 5 years ago in cool and warm white to use in my car. Didn't know they were still available since they look quite expensive to produce with the glass tube.
Those could be little test tubes, they do make them that small, and there's plastic and glass versions
These would be really handy for LED conversions on older, small capacity motorbikes for a couple of reasons. One is they will often be running either dirty halfwave rectified and un-regulated/poorly regulated charging systems or even straight-up unregulated single phase AC for the lighting. The other is the indicator dash repeater bulbs often run the DC in opposite polarity depending on which indicator you're using. Even incandescant bulbs struggle sometimes and cascade bulb failures are reasonably common. These seem like they would cope with all of that madness without too much stress
Leds are great, for old 1980's bikes with 6v electrical systems and a tiny battery than can't really even run the indicators and the brake light even when everything is brand new.
I love the way you are so knowledgeable but put frosty jacks in a soda stream. Thank you so much.
Forget the circuit... This is the style of LED I've been saying drop-in automotive LEDs should be! Actually keep the light source in the original location within the fixture so the light is properly reflected. All we need now is for this to work its way to the bigger lamps!
I like that this has a filament that is starting to mimic the same position as a traditional bulb. That's essential if your lights are going to focus properly. Would love to know how bright this is compared to the 5w wedge bulb it replaces.
I love a cute box !
Most definitely...🤭
I was reading the datasheet as you were explaining the circuit. The part that says, "Oh, you shouldn't need to stick a diode on the output because we've got that mostly covered" made me chuckle a bit. They don't describe current regulation _per se,_ but they do mention a constant current between output and adjust pins if there's a resistor connecting them. Very clever use of this LDO regulator, and you don't need a big inductor like with an AL8860.
Interesting use of a regulator... I love your videos for discovering these types of details!
It's a standard use for a voltage regulator. You could do it with an old '7805 but the later LM117-style and lower dropout regulators are far better suited to it. As the 1.25V is derived from a bandgap reference it's very stable and makes a good and cheap voltage reference.
YES...Me too !
@@Graham_Langley It might be a common use, but most hobbyists like myself are probably not familar with it... being a voltage regulator and not a current regulator will limit searches for such circuits 😺 - when I saw it, I was from "what the..." to "oh, that is smart" in a few seconds, but I never seen it before and that's why I love Clive's videos. A nice source for such little tidbits without reading boring data sheets all day.
Please continue this series, lots to discover...
Nice little lamp!
I might have to get some of these for my step-dad's truck...and excellent replacement bulb for his old filament lamps when they finally go bad.
What a nice design. I have this exact style of lamp in cold white as a position light in my car. Looks neat and matches the xenon bulbs.
Good to know that they don't run directly on the supply voltage.
I wonder if the reason for the rectifier is to avoid damaging the voltage regulator with reverse polarity.
In any case, it's gratifying to see manufacturers using a rectifier in this way. As you say, it is quite easy to reverse the device to make it work, not so easy when the lamp has a bayonet cap! My car (a Ford) has positive shell and negative pin, the opposite of most vehicles.
The LEDs themselves would protect against reverse polarity.
Allows installing either way and also drops another volt or of the circuit.
Same thing I was thinking.
Thank you Clive. I have never seen or thought of using a voltage regulator in that way. Very interesting.
Look in the data sheet of the LM317 - it has a number of "unusual" applications of an adjustable voltage regulator. One of them happens to be a constant current source, but there are a number of others
love these practical n ingenious little circuits
That's a old school way of turning a voltage regulator in to a constant current supply. Used to do this back in the 80's to charge nicads. Nice to see some old ideas still being used.
A nice little lamp.
It's a nice bulb replacement for some vehicle interior lighting where the circuit board style ones won't fit, for example 2005-2015 volvo dome lights. Plus it's current regulated, so the alternator is less likely to kill it.
I’ve learned more from your videos than from three years of secondary school electronics.
I have just torn down an empty 50ml Cetraben emollient pump dispenser and it might be worth considering for a short mechanical video. It has 9 components, excluding the contents & label and is rather clever. The magic happens via the small hole in the bottom!
Curious if this lamp can be pulse width modulated given it has no capacitors. My car's dome light fades out instead of shutting off abruptly
The fade is probably there by design. If there is a cap, try a bleed resistor across her.
It should dim as expected provided the PWM frequency isn't too high.
No CAN bus resistor, so it will set a fault code on vehicles that monitor the continuity of the lamps continuously. Simple to fix, a 220R resistor across the pins will allow enough current to flow.
Those AMS1117 regulators are everywhere. I've started using them in preference to the 78 series as they are a bit cheaper too.
The trick of using the adjustable regulator as a constant current source comes directly from the LM317 datasheet - it actually has a number of "unusual" application circuits in it that can be quite handy. I always lump the LM317 in with the 780x regulators in my head.
AMS1117 is a LDO (low dropout reg... dropout voltage of 1.2V) LM317 is higher... about 3V... newer version of 317 might be better.
@@willthecat3861 I got some AMS1117-3.3 to mess around with some tiny adapter boards, and added a resistor as here, resulting in a LED current source with a similar overall forward drop to the 317 circuit.
For automotive applications, you'd want to use voltage regulators with at least 40V max rating so they don't immediately blow up on the slightest alternator-battery hiccup.
Ideally 60V. Typical standard levels of survivability for automotive transients is -40V to +60V.
That's standard design practice, but any remotely modern vehicle won't produce those voltages. "Load dump" spikes were a problem with slow regulators, mechanical voltage regulators and early electronic regulators.
@@1djbecker Although many newer cars (where "newer" can easily be 10 years old or more) use switching supplies for the 12V, isn't inductive spikes from switching loads still a thing?
Very interesting find. Awesome exploration!
Reminds me of some years ago using LM317 to CC drive =>1W LASER diodes.
Popping balloons, lighting matches or candles and even a few cigars... Fun times!
That trick of using an adjustable voltage regulator as a constant current source comes from the datasheet of the LM317. It has a bunch of "unusual" application circuits in it - the LM317 (or any adjustable voltage regulator) can be used in a number of non-obvious ways!
@@gorak9000 If you're a fan of "unusual applications" of company ICs, search for (my favorite) "555 based solar charge controller" for almost everyone's favorite IC adapted to a seemingly unrelated function.
Another great video 👍 thanks Clive,have a good day
Clive your reverse engineering presentation skills have gotten *so good* since you started youtube
Neat automotive bulb, more and more such bulbs seem to have regulation which is really nice. No dimming when the voltage varies, even when starting.
It's nice to see constant current regulation, on 12v LED car lamps. It's so much better than just a resistor, for the variable voltage 11v-15v in a car. I guess the circuit would also of worked, if used as a voltage regulator, with a current limiting resistor for the LEDs. If the regulator was set close to the total forward voltage of the LEDs, then the current limiting resistor could be small and low value.
Content free comment to drive engagement for my favorite channels
And it's more foolproof - the full-wave bridge rectifier provides reverse polarity protection.
I would like to know if this was meant to be a replacement lamp for instrument clusters, behind the dashboard. No more burned out lights hindering the driver! 😊
That's a bright idea
Used to use the LM317 in the same way....cheers.
That was pretty cool I must say.
I got some 39mm Festoon LED Car Bulbs and was surprised they work whichever way you insert them. So they must have a bridge rectifier. I haven't tried to take one apart to see if they are current regulated or just a resistor. Actually it might well be that all car bulbs are current regulated so the brightness stays constant regardless of the voltage on the nominal 12V bus which can probably vary quite a bit.
Some are some are not. The ones that run on anywhere from 10v - 30v must be. I measured some that were using 500ma on 12v and 250ma on 24v . So as you increase the voltage they reduce the current they use, if you get below 7v they start flashing like a strobe light.
For automotive use the nominal voltage is 13.8 volts, but should be expected to vary from 9.5 (while starter is cranking) up to 15.75 (charging a low battery with very cold temperature). Ideally one should design for possibly nearly 24v peak to peak AC on top of the DC voltage.
@@chrishart8548 If the current goes down when you increase the voltage they must have a switching converter. Very fancy as well as relatively unreliable.
If you are here, in the New World, you can check out the Sylvania ZEVO brand of white LED mini lamps, for automotive interiors fixtures. It is also non-polarized (just so the old folks don't wonder why the dang thing won't work, when you plug it in... when a good 'normal' light bulb always would.) Anyhow the OEM is DE3175.
i love these things. They look like they were DIY made. But there's a machine somewhere out there that just holds these tiny little LED glowsticks and solders them together in this funny shape.
There's a good chance it's largely manual.
Thnks man .
I built many a hacky DIY Ni-Cd battery-chargers back in YeOldeDays using a TO-220 7805 and a "current-programming" resistor
These look like a good fit for interior car light.
The filament ones burn often. I wonder what the current through each LED is? Not 82mA for sure.
With only 8V voltage drop across the LEDs, they are surely in series/parallel configuration.
Longevity will depend on the current through each LED.
What a bright idea! 😁🇨🇦
I forgot my glasses and read - Heat vehicle lamp, now that would be interesting :D Heat LED lamp:?
Interestingly, 8V + 1.25V + 1.8V + 1.5V = 12.55V, plus there is some drop-out across the regulator, so the regulator isn't really cutting in until the supply voltage is over ~13V.
That lamp would consume a bit over 1 Watt. Some get radiated away but 1 Watt will make that lamp get quite warm.
The auto closed captions called it the KINK calculator! 🤣
Cool little lamp!
It is pronounced "kink palculator" ;-)
That’s the same circuit of an RV puck light. I was able to change the set R to dim our reading lamps.
They finally have a long-term LED replacement for the ever ubiquitous and venerable GE192 "peanut" bulb?
I have a version with two pins, rectangle filaments and dipped into a sillicon rubbery type of solution to form the 'bulb'. It runs on 12V and polarity doesn't matter.
3:48 And that's mah new desktop :)
If you could post a 4k photo of that that'd be really nice clive :)
That 1117 regulator reminds me of an LM317
It's very similar.
These might work a lot better for older cars that use filament bulbs. Many o the LED lights if you buy them in the UK saw they are not indented for road use. 🤦♂😂
A lot more going on than I expected 2x👍
Some of the more modern cars detect if a bulb has "blown" and report a fault if LED bulbs are used to replace filament bulbs, so unless your car is designed to use LED light bulbs you may well end up with a fault being reported when you replace a filament bulb with an LED bulb. The fix used to be to fit a large wattage resistor parallel with the LED bulb to mimic the current drawn by the original filament bulb to avoid the error message of a blown bulb being displayed.
I'm not sure what the latest cars make of the user replacing the original bulbs with LED bulbs, though.
KW.
@GetCarterCarPark ... I'm not sure that it's a 'current draw' that is used to check for blown bulbs ... I put one early LED in my '95 truck (combined stop/turn signal) without the extra resistor ... The turn(/stop) on that side started to trip the cruise control ...I don't know if it was sensing the 12v when the brake light was on, or if it was using the bulb as a pull-down resistor ... I wondered if a high value resistor in parallel would have worked - but never investigated ... I know that the high brake light had to run off the switch on the master cylinder (which is PRE- flasher?)
@@jayherde0 On a 2000 Accord there is indeed individual current sensing for both of the main brake lights, I don't know what the threshold is. What happened with your truck doesn't make much sense but I can think of one remote possibility. If the bulb has a non electrically reversible base there could be a capacitor inside the LED module. When the turn signal turns off the lamp would be reconnected to the brake switch and the charged capacitor would provide voltage there for an instant before the high brake light would discharge it. The cruise module could see this blip and interpret it as you tapping the brake pedal. It just doesn't seem very likely that all those conditions would be true.
Hi Clive - At what volts do the LED'S start to light? As I have found Running the Lamps on 10v5 they do not get as hot and consume less current and make great work bench emergency lights run from a 18650 charger VV booster and can run for a couple of night with out charge.
They should start to glow at that level.
So cool!
When one has that much "head room" one can do things like that
There are some comments about it mimicking the filament for proper "light bouncing", but to me it looks far too big "filament" in this one compared to regular W5W bulbs. It is a nice design tho, with proper current regulation.
Are the 2 x 8 LED strings in parallel (as said at 4:30) or in series as drawn?
Insightful video as always.
There are three parallel groups of LEDs in series.
@@bigclivedotcom Ah, that explains a lot. So the voltage drop over one LED is about 2.7V.
@@jurjenbos228 Typically between 2.5 to 3V depending on current.
cool, looks retro.
Are these bulbs available for a lower input voltage? Because that light would be great for pinball machines, in the spaces where the bulbs are visible on the playfield. Older pinball machines often use 6,3 V for the light's. Some AC and some DC.
You can get lamps matched for pinball use, and also new driver boards that work better with LEDs vs tungsten lamps.
I wonder if the filaments being different brightnesses is to allow them to be used in combined stop/tail or stop/park replacements where you have a dimmer red all the time at night and a brighter red when braking. Obviously not implemented here but maybe they have other versions
I've never been able to grasp transistor theory, lol and I still don't. Digital...easy as can be. Analog kicks my ass but I'm going to keep watching your presentations until I get it. Thanks for your wonderful presentations.
It would be good to see how it stands up vibration and voltages around 13-14v.
I have gone back to standard old halogen globes in our cars as the leds lately dont even out live the bulbs......
Thanks 😁
Hi Clive, this may be an odd question but what pen are you using? It looks like a good little felt tip
It's a Pilot V-sign pen.
A similar circuit is used by the 12 Volt , warm white ( G4 pin base ) lamps , sold in many shops ... the regulator is handy , should the voltage rise ( 14 Volts ? ) , the current DROPS to give a constant brightness ( and vice - versa down to about 10 Volts ) .... the BIG problem with LED bulbs in cars , is that they use MUCH less current than filament bulbs , sometimes confusing the car's electronics ( says : bulb blown etc ... ) , VERY handy lamps in case of power cuts or camping , BTW .... DAVE™ 🛑
Spring point meter probes are great for keeping probes on a contact point.
As with a pair of alligator clips on a board holder.
One for the board and one for contact point.
The sun is setting so the drinks are poured.
Hope you enjoyed the drinks and chilling out on UA-cam. (Makes for a good evening.)
Using the diode bridge isn't really less efficient since the regulator is a linear one. If the diodes weren't there the regulator would have to dissipate more power.
I was thinking more along the lines of potentially using four sets of LEDs in series for greater efficiency. But the three sets do allow a wider voltage range.
What’s it’s intended purpose? Is it a LED substitute (upgrade) for an automotive incandescent lamp?
Yes it is.
@demef758 The infamous 117 crap. Have experienced dying expansive circuits when / because the THERMAL capacity of the IC itself is tiny small and the underlying cooling area did not dissipated the heat quickly or was too small.
The issue happend to me on professionally made units and home made projects too. The dead of the 177 caused expansive losses when it burned ALL the powered circuits on the pcb & subsequently the LED displays.
The thermal over protection DID NOT WORK, never. No shutdown was performed.
It shut cut off the load entirely when it reaches the max current /max temp.
very interesting. tnx
So do you like it? I've become a whole lot impressed with you opinions!!
*How much could the tiny rectifier be?* 🤔
I mean, it's not ECE-compliant anyway, but it makes these LED-"retrofit"-lamps easier to use! 👍
Nice, worm "tungsten" light. Chinese 1117 copy of TI regulators aren't exactly voltage regulators, but more like 317, and though still very popular are rather outdated - not low enough voltage drop and a rather high voltage reference for current regulation.
It would be nice to include power dissipation calculations. The 22 Ohms resistor for example gets more than ¼W and I'm not even sure of its rating.
I wonder if there is a 6V bayonet version of this type. It would look and work better than the leaded LED and dropping resistor type.
I think most are made for 12V, but a 6V one may exist.
Lovely video and lamp!
If possible, I would love a link for this or a similar lamp of such high quality.
I have not seen this little marvel on the webz before. Most lamps with this socket are pure garbage.
It was a random eBay find.
Many thanks. Learned about using a rectifier for DC polarity determination. The light given off seemed very modest. Where in a vehicle would this be used?
I'm not sure of its intended location. Possibly instrument illumination or a side light.
Interesting. In future videos, a canbus led bulb? Thank you, and more to the video
Most "canbus" LED lamps just use resistors to increase the load. Some I looked at got so hot that they melted people's lampholders.
It looks like you drew the parallel LED strings in series.
Hi could you please do some stuff for us electricians who can't really follow the diagrams please . Explaining things for us new to electronics
Would be interesting to see the dye package
On a side note, the 3voloution air fresheners you covered previously, now bost new smart programming, personally the look exactly the same with zero changes to the outside, maybe worth a revisit?
I took a look at a recent version not that long ago. It had an interesting memory function for detecting a cartridge change while unplugged.
Nice smart design - I like it but wonder how we got from a bit of resistance wire in a glass envelope to a electronic module and ceramic LED strings 😂 and I bet it's cheaper to make!
It's like how now it's cheaper to have backlit TFT LCDs than analogue gauges so the cheap cars are all TFT and the expensive ones have analogue gauges. Which would have seemed insane 10-20 years ago.
Hi Clive Just something which may or may not be anything to do with this type of bulb, since buying my Vauxhall Grandland every so often whenever I put the right turn indicator on I get a fault indicator and my incarinfo tells me to take my car to the nearest garage, I have done this and they are not sure what the problem is but they think that on some cars who have halogens and not LED's (this could be the other way round) could be the cause ,but as I told them why only on the right turn
If the car is designed for regular bulbs but an LED is installed the lower current draw could make it think the bulb is burned out. But if an infotainment is saying to take the car for servicing just because of a burnt bulb it doesn't seem like a very good system.
@@eDoc2020 I wonder why Vauxhall has not came up with this, It is something I will check that myself , thanks for the info.
I never considered using a bridge rectifier for polar ambiguity
Pretty much the same how 78xx regulator was used. I guess ams 1117 is the new 78xx these days.
I have been trying to figure out how to use an AMS1117 for a while now. I saw that and said, "Hey, I've destroyed DOZENS of those!!!"
That's like the LM317, same topology inside.
Nice
The only leds in my car that hasnt burned out after 4 years.
Even better if you modify it to have 4 filament.
Or combine 2200k with 3000k
Is there anything BigClive *won't* disassemble and reverse engineer?
I'll have a go at most things.
V. nice reverse engineering job - these things are tiny! Clive do you think the bulb was filled with heat conducting gas to help the cooling? A lot of the glass LED filament bulbs are filled with helium , which transfers heat from the filament far better than air would. That's how they get away with using no heat sink on the higher wattage specimens..
No gas as there was an open channel between the cover and PCB
At 4:25, should the first two x8 LEDs in parallel be drawn as such instead of series before the x10 LED on the schematic?
I think they are even more in series than that. As most LEDs have a power drop around 1.5-2 V, I guess that they are even partly parallel inside the units themselves. Clive, please enlighten us.
are those available in orange or orangish white (1800K) ?
would be quite neat source of diffused warm light
I think they are available in a wide range of colours.
Looks fab Clive, I think they’re coming up with so much interesting ideas now thanks 😊
Since Tesla is currently a bit over 12 V, and will move to 48 V for its low voltage this year (the Cybertruck will be the first), would this work for about 50 VDC? Something similar would work, at least.
It wouldn't be suited to that voltage.
It would be nice to know the ebay search terms for those lights. They look like they might last a bot longer than 501's tungsten or LED bilbs thay overheat and birn out in a few weeks.