Inside a better quality Elitech thermostat (with schematic)
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- Опубліковано 6 жов 2024
- This is better! There's a reason traditional core 'n' coil transformers are used in stuff like this. Using an old fashioned transformer gives better electrical separation and gets rid of the stressed out low-ESR capacitors.
I didn't originally intent to go quite so deep with the schematic in this, but it turned out to be quite interesting inside. Note the custom badged relays, which I would guess are of a better quality than the Chongle clone ones. The thermistor is the classic 10K type (10,000 ohms at 25C), but injection moulded in a plastic case like some of the industrial ones I recall from my Hussmann days.
This unit is notable for offering a choice of celcius or farenheit display, but changing that option will reset all the existing settings.
The allowance of circuitry positions for an RS485 network is intriguing. Especially as the address setting facility is already in the programming menu. I'll guess it's for remote monitoring of multiple cases. There are three pads for a connector, but only the RS485 data lines are connected. For the screen/reference the thermistors 0V connection would have to be used. So this may be a work in progress.
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Elitech has a number of product available, including WiFi capable line powered devices that have electrical outlets to control temperature and humidity. The one you presented sells for about $20 USD.
The four pads on the front of the display pcb are almost certainly Reset, SWD, Ground, and Voltage for the STM micro on there. This suggests that, with a bit of reverse engineering, you could roll custom firmware to add more features, especially around the serial protocols.
Depending on which STM that is, they may be using a DAC to do a chopper style stimulus of the thermistor, to avoid noise. The cap in parallel to with it would probably argue against that, though. In any case, by tying it to a GPIO, they enabled lots of handy tricks for finding out if stuff is still working as expected,or if it's gone a bit off the rails.
A very cute unit, clearly done by people who know what they're doing and have pride in their products. Bit of a contrast to the last three, to say the least.
The GPIO powering the thermistor is to avoid 'self-heating' - the current used to measure the thermistor's resistance has to be dissipated as heat, which would make for slightly less accurate readings. If the reading current only pulses on for 1 millisecond per second, the amount of self-heating is much lower.
I've heard about custom firmware for the Inkbird ones before. People would use it to do things like ramp up the temperature over an hour.
"12 sold in last 16 hours" says the manufacturer's website. I wonder if that's the Big Clive Effect coming into play? I don't imagine they'd normally sell that many on a Saturday!!
I had to go take a look at the Elitech products after watching this video. They are only slightly higher priced than the clones I've been using, but well worth few extra dollars. They aren't switching any heavy loads in my application (only about 3 amps at 110v), but as soon as the Clive had the case open it had a more professional (and safer) look to the board layout.
0:55 Quite thoughtful to include a sound effect when unlocking the padlock.
They even made it sound like a gun cocking to discourage you from doing it. That was nice of them.
The display is showing an ambient temperature of 15.8C. Bit of a heatwave for our Clive.
I'm sweltering.
I get irritated if my lab is less than 21C.... brrrrr
Given that I used to have an outdoor "lab" in Arizona USA with typical daytime temps around 42C, he'd positively melt there.
60.4° Freedom Units, not terrible, I was expecting something in the low 40's maybe, lol.
@@idjtoal - "Freedom Units"... LOL. There are better "F" unit names... Fahrenheit was was high tech 300 years ago but it's time to move on to a system that makes sense! :-)
I also like that the caps are voltage rated about twice the operating voltage, good design.
I think the compressor delay is the number of minutes from the last time the compressor was running, not since the differential temperature was reached.
Yep. I've always referred to it as "REstart delay" for that reason. I think the idea is that the system pressure begins equalizing as soon as the compressor stops.
@@sootikins One of the experts at work told me it is to prevent the compressor oil from foaming up too much. On every restart the oil gets mixed with refrigerant in an uncontrolled way and foams up a bit.
Another reason is that a compressor has a hard time restarting under pressure, like working against a brick wall which can stall it and lead to overheating (locked rotor).
I can also imagine that restarting a compressor often will stress its start windings.
I was just about to write that, lucky you are on top. That is preferable to being on the bottom I hear lol.
exactly what I was thinking. Don't want a compressor cycling too often.
@@loonyloony6550 Don't knack it until you've tried it, sometimes it's fun! Unless its trying to lift something.
5:39 - The delay is probably just between operation cycles, not between the moment the compressor is "requested" and the moment it's turned on. Since it hadn't been on since the reset, the delay wasn't applied. It would be applied only after it turned _off._
That's correct. Most thermostats have a fixed setting of ten minutes, which is applied to the start of the AC mode, it will not turn on the compressor until ten minutes has passed since the last time the compressor was on.
I like those transformers, we used to buy them with premium cores to reduce self-heating. One of the main reasons they lost popularity is that they are not universal voltage so you need an extra winding and maybe extra terminal for 120V and then there's 100V/200V Japan to deal with...
The MAX483 is an RS-485 transciever. On the MCU side, it requires TxD, RxD and TXEN (TX ENable), all TTL. I use these in many of my projects.
I very much like the display. That's something we could replicate easily with a 3D printer and LEDs on the circuit board.
I also strongly suspect that it speaks ModBus over 485. I kinda want to get one of these and see if it responds to any registers.
@@hpux735 Yes, I was going to say the same exact thing. ModBus. But you beat me to it
Nice to see a linear regulated power supply in a modern piece of electronics. I'm so used to seeing everything with a switching supply, it's what I'd expected.
I had the basic STC 1000 on my freezer kegerator. Perk of homebrewing, always innovating
@@thefalseshepherd3689 I built mine when ink bird was a kickstarter, just got in the forums and made it work.
Most remarkable thing about all of these that I've tried is how well their self tuning PID algorithm works. This type of controller used to cost more than a new car.
I suppose that was when any self tuning PID algorithm required a PDP-11 to run on?
This has no PID algorithm, tuned or otherwise. It's essentially a dumb thermostat with a time delay added. In the 1970s and before this would be done with two adjusted thermostats set to the +3 and -3 degree temperatures, a mechanical time delay relay, a few basic relays to do logic and output, and a 24VDC power supply for the control modules. By the 1980s, the relays and other modules would plug into 11-pin sockets on a DIN rail in your control panel/box. By the late 1980s, PLCs could do the job themselves, but would still cost more than the DIN rail modules, and early versions of these all-in-one thermostats started to become available.
@@johndododoe1411 Indeed--the PID controllers that I've played with usually have two displays and a very involved menu system for setting the various constants. Still inexpensive (usually < USD$30) but quite handy.
@@johndododoe1411 You could be right. Certainly the unit I bought for around $10 is a lot smarter than the bulb thermostat I use for a different application. The only way to know for sure what you're getting from most online vendors these days is to buy the thing and test it. All the patents related to PID control seem to have expired. Not that patents ever had much impact on Chinese manufacturers.
@@andreasu.3546 From dim memory they were a unit about the size of half a shoe box. There's also a cloud hanging over the value of any "self tuning" I believe. Keep in mind some of these devices were being used to control furnaces bigger than a block of flats.
I worked in SCADA but still rubbed shoulders with the people responsible for the measurement and control of a process.
One thing I can throw some light on is the importance of selecting the best sensor for measuring temperature. The PT100 and PT1000 sensors use the resistance of a platinum wire as the way to measure temperature, ideally using a bridge. For lower temperatures and cost there's thermistors and for higher temps than platinum can handle there's a range of thermocouples but they bring their own issues e.g. they actually give a voltage proportional to the temperature difference between the cold and hot junction.
The original brand is Eliwell, an italian company. They make the units for pub bottle fridges and supermarket freezers.
I have an Alpicool 12v freezer and it has similar functions for restart delay and Hysteresis band adjustment via the Bluetooth app. Both help to prevent frequent cycling of the compressor due to temperature fluctuations suggested by the sensor module which itself can be majorly affected by its proximity to warm components or drafts.
I think that icon is for Dehumidify.
The display at 1:24 doesn't look crispy sharp, especially the "sun" indicator. Perhaps due to the type of diffuser or maybe because of the digital camera zoom.
Clive, I'd like to see you do a teardown on one of the higher-end heat/cool thermostats made for home use. When the new heat pump was installed in my home, the installers looked at the old thermostat wiring and noted that the bundle had only 7 wires, where 8 were called for. "No problem" said they--and came up with a thermostat (color touchscreen LCD Honeywell) that needed a connection with only 2 wires. The base unit has lots of options, including net connectivity, and remote outdoor sensors. I imagine that the whole setup is rather complex, but it's done well for several years here.
I think it's just better because it has that seven segment red LED that reminds me of things that worked forever
Very cool with the additional features.
On my channel I've got a rundown of how I used one. Gutted a destroyed UPS, and wired it into the input/outputs. Use was for a brewing setup where the cooling point goes to the fridge, and the heating goes to an electric blanket set to its lowest value lining the inside of the fridge.
Great units and fantastic to see a full workup of the insides of it. Love your work mate.
Powering the thermistor from the micro lets you find out if the thermistor is attached or not and it's not just smegging cold/hot
As well as driving the divider from a Vref instead of 5V rail, you reduce any errors from slight flucturations in the 5 V rail, output from thermistor will be a ratio from 100% as seen from the ADC point of view.
@@jangoofy hadn't thought of that, though I guess you'd have to look at the extra noise you introduce running though the chip and if your using vdd as the reference not an internal vref
Interesting to see inside one of these. I normally just replace these type of controllers and throw them away, rather than looking inside.
It originally looked like it was a red back lit LCD (segmented) because of the lower contrast where you can actually see the unlit segments and because it has those custom symbols. You can also see fading at the ends of the segments that aren't getting as much light from the LEDs. Using a red diffuser (instead of grey) would have helped.
I bought one of these after watching your other video! I *think* Elitech was the original brand of the STC-1000. I made a little 3D printed enclosure to contain and strain relieve the mains wiring a bit. This one feels a lot safer than the old knock off jobbies I was using a while ago for home brewing.
On the display being a light guide over SMD LEDs, Fran Blanche very recently took apart an old clock that was built that way. Some things don't change...
That was actually neon, wasn't it? If it's the one I'm thinking of? (the old Japanese clock)
The most recent one with the LED display may have bare LED dice with bond wires on it.
I had a clock radio in the early 90s that was built with SMD leds.
I would love an RS-485 version of this. I've been thinking about building a smarter climate control system, without resorting to the off-the-shelf "smart" devices. RS-485 means I can tie it into a sensor network, and make decisions based on the state of the _whole_ house (as opposed to just where the thermostat is). It also means no Ethernet or Wifi networking overhead. Very nice. 👍️
Great Video's Clive. In Australia i see these thermostats in commercial Natural Gas hot water services.
also common in commercial refrigeration units. I've never seen the networking address used yet. Handy tool connecting these to Building Management Systems.
I’ve used most, Lae, Carel, Dixell, and many others, I can say they are all mostly good, but for features and reliability I use carel, mostly the IR33
Compressors always start under load and need high torque and high start current. This causes the windings to heat up. The delay prevents the compressor from starting again until the motor has had a chance to cool off -- the delay is measured from the time the motor stops.
Hi Clive, love your videos, I use an Elitech ST1000 on my fermentation fridge, I had one of those cheapo one's but it went bad, so I bought an Elitech, if you weigh that and the cheap ones you have you will see a considerably difference in the weight. I thought it might be of interest to you👍
The compressor delay will start at the time of the last stop, not from when it commands a start. It;s meant for then something might want to cycle off then on again in short time.
You could have a look at the Inkbird ITC-308-WIFI unit. It is designed for things like reptile enclosures, where you need to maintain a close temp tolerance, as it can control heating and cooling all in the one unit. There are 2 versions, one with WiFi and the other without. With the wifi version you do all the programing via an app on your smart phone.
Got one for the brewbelt on my home-made wine fermenter and it works a treat. Thanks for interpreting the instructions Clive-much appreciated
The CPU will be outputting the A/D Vref, probably 2.5V, to bias the thermistor.
Clive after getting bored playing with his toy: “Let’s take it to bits!”
The transformer looks like an EI pattern bobbin and depending on what it's for would either have a shroud around the windings which is safer from damage to the windings when laminating the bobbin. If there was space and you wanted to save money then tape can be used but it's not as good. Used to make them a long time ago.
The pattern name comes from the shape of the laminations, the ferrous metal plates that make up the magnetic portion of the transformer. Looks like what I would call an EI38 bobbin, I did notice some damage to the tape when they shoved the laminations in.
Great video. Lovely to see your photographs and reverse engineering. Keep up the good work.
I have used both the genuine elitech units as well as the cheap knock offs, all 240v units and to be fair to the knock offs I've only ever had one fail and that was after over two years of continual use!
It looks a bit like a clone of an eliwell controller. Very similar name too 🤔
I've used these in mimic panel's for external chillers in a factory and for mould coolers inside the factory...and they're good but the relays do fail ..I've modified quite a few of them to use external din rail mounted to relays so less technically aware techs can swap out the relays with no soldering.
All that said they're really good value and they offer quite a range with many functions.
The relays failing is the most common failure point on most makes not just elitech as they're often used to switch 24vdc to control external contactors in industrial settings .
Make sure to put suppression diodes on the external contactors. It makes a huge difference in relay life.
I may get one for a project I want to do for years. Really interesting
I like this is better than other one (STC-1000) because more everything tools there and new. I like your draw more clear explain. Good job!!
Looks decent thank you Bigclive some of the things you find to take apart and reverse engineer are pretty cool
I thought for a second this was a DAC/Amp, I thought you'd now become BigCliveDacAmp
The refrigeration controllers I see most often are CAREL from Italy… I suspect these EliTech units are a chinesium clone of the Carel controllers.
The operation and features are almost identical.
I have one of the elitech STC-1000 running my heat tape on my water lines and it looks like the other's you have taken apart. It's the standard style STC-1000 elitech branded.
I got an Elitech STC-1000 Pro in 2020. It has two heat inputs instead of one heat and one cooling. I used it to heat up and spin two fans in a cabinet in my shop where I keep my glues and finishes and such. It worked for about 1.5 seasons but one of the inputs failed. I couldn't figure out what the problem was so I went to buy another one but the price had went up significantly so I got another brand. The new one wouldn't turn on but I was able to find the fault, B/O solder joint on the input.
In an electrical system NEVER assume that what's designated Neutral actually is Neutral. In industrial systems you might have a solution of 230V between 2 phases in a 3-phase solution with floating ground. This would lower the risk of someone getting hurt if they accidentally touch one phase unless one of the phases connects to ground. But then the system can have an alarm detecting a ground fault issue. And if you don't have a polarized power plug on a device it's a 50/50 if you have hot or neutral. (Movie quote "Assumption is the mother of all F:s)
So I'd prefer to have a protective ground connector separating the sensor input from the power supply. Even if the ground connector is just a "dummy" connector it could be enough to create some safety space - and many cables do have a ground wire so it would be nice to have somewhere to "park" that wire. I usually don't like to have to cut wires in a cable unless I positively know that it never ever is going to be used in the future, and that especially goes for ground wires.
For anyone involved in Amateur radio - protective ground and signal ground are two completely different things.
I'm a bit curious about when we will see the first device that uses a solution using LEDs and a solar cell internally instead of a traditional transformer for powering a device.
I have a backlit lcd digital thermostat on my central heating and it has a differential that really annoys me but it never occurred to me that I can probably set the differential!
The thermostat has all sorts of features but I never bothered to read the instructions as I only cared about it operating as a regular thermostat and Dont care about all the programming but I should read the instructions now and see if I can change the differential, I just assumed it was how it was designed and that was that!
Most of these industrial type devices will have modbus and it uses rs485 which all have addressable functions which allow you to remotely monitor the operation. It doesn’t look this particular model has that installed though - probably why its marked as reserved under f6
I am working in a factory making industrial and supermarket refrigeration units, freezers and coolers. I work with MANY different kinds of these thermostats... you want a couple of damaged or faulty ones? I can probably fish some out of the electronics t rash bin :D
Interesting that the board was marked STC-1000B rather than X on the outside of the unit. I'm guessing that's just the internal part number for the board itself, and the X is the model of the full unit.
We used Elliwell controllers where i worked, this must have been about 20 years ago when we started.
I notice RS are doing some similar controllers to yours with their branding
It's nice to have the fancy corners, but you'd have to be accurate with cutting the hole
Eliwell is still being used in tons of kitchen appliances. For cooling or heating. It has a bunch of settings for every need :-)
Sometimes the compressor delays is only at first power up. Or it could be a delay between two successive switch ons.
The aux is interesting, means they have a design for a heatpump furnace combo unit. and one in deg Frankenstein so 120V potential. Thanks!
Nice to see a (fairly) decent thermostat. What was the price difference between this and the junkier one you did earlier?
Hi BigClive, I’ve been watching your vids for a while and also watching a few paranormal programs like ghost adventures and paranormal lockdown and many others on UA-cam. I always wondered what’s inside some of the tech they use like the Melmetre and rempod etc and what if anything they actually is measuring or detecting. This would could be a debunking paranormal devices playlist. Is that something that would interest a electrician or a magician? Any thought everyone?
Thanks for the informative vids mate 🇬🇧✌🏻
the paranormal is ALWAYS interesting!!... too bad it's bullshit :D
i like this idea of analysing such quack devices
I use Elitech temperature loggers. Quality, accuracy and functionality is adequate to good, and very good VFM, but they don't seem to have any CE marking so are technically illegal imports.
I rate the Elitech I’ve been using them for many years. Pulling around 8A straight from the unit I wouldn’t recommend it like you’ve said previously use a relay
Looked at their page and they sell a enduser friendly version with plug and two sockets ready to use (230V 2P+E, EU)
one for heat, one for cooling. (edit: i hope the earth isnt missing as seen on the product pictures..)
I could be wrong but I believe the differential is half the value either side of setpoint eg, setpoint 20 diff 2 - dead zone will be between 19-21 giving a 2 degree differential. Let me know what you think.
This is the case for most refrigeration controllers unless using PID and TR
Edit - I should have watched more then 2 min before commenting
Way better quality indeed !
If you search for STC-1000 (the predecessor of this one) its design is pretty much the same of the cheaper ones you shown in the other video so I think you might be right in saying that those cheap ones are clones of it
Thanks from Texas Clive
I watched about 02:20 of this before I realised I was watching a vid about the type of device (and menu system) I detest. My parents had a wireless heating thermostat installed. The problem with it is that they keep picking it up and moving it between rooms, during such time they inadvertently press control buttons and change settings then wonder why the heating is on at midday but not during the morning. Either that or they are trying to beat the laws of themodynamics somehow [which I doubt].
That's why it has a lock function.
@@RedwoodRhiadra THANKYOU. I need to find that!!!!!.
@@RedwoodRhiadra It's a "BOSS 957707" It doesn't have a lock on it. Would have been useful - given how they get thrown around (AND DROPPED frequently).
modbus is 31 devices but profibus is 126 + 1 - that would be something else if these had rs485 profibus capability - in saying that looking at the terms perhaps a coms board is an option
Ahhh proper transformer a) I understand them b) far more confidence in the unit 😊😊😊
On their site the 1000X write mentions a E1000X with networking and looks very similar so same board different options. Unfortunately they don't list it on their site
The original one you have looks like a clone of Honeywell controllers. I used to use something like those on Furnace controllers.
15:04 Clive has cracked the MCU ( marvel cinematic universe ) diagram of spinoffs and tv shows. I see what you did there....
MCU is the industry abbreviation, since way before the Stanlee cartoon company created a series of interconnected movies.
@@johndododoe1411 oh, did you see that. It was right above you. I think it was the joke.
Elitech-not-Keritech, haha :)
Nicely designed electronics inside, and it's interesting to see their brand on relays as well.
Personally I wouldn't waste GPIO lines on MCUs for segment on 7seg display, unless the controller had a whole whopping damn lot of them. When running out of lines, I'd go for a MCP23017 or similar GPIO expander.
Thank you for yet another entertaining and informative video. Did you measure the power consumption of the thermostat? I would suspect that the transformer produces more heat than a SMPS or just a series condenser based 24V PS. And a LED display is probably not as efficient as a LCD display?
The manufacturer lists an overall power consumption of less than 3W for this particular model.
I suspect these were cloned off the similar Japanese Omron controllers.
Check out Ink Bird controllers.
Voltage output for SSRs and the autotune for PID control works pretty well. Not as good as a Cal or West instruments but at a tenth of the price can't complain.
This is a particularly well made unit!
So that's why these thermostats have buttons. I thought they just showed the temperature and changed to celsius or fahrenheit, making the buttons almost useless or to just have them there for looks
I notice that there are 2 pads on the bottom of the circuit board marked A and B but without a connector. Are these the RS485 terminals? Your diagram just indicated those going off somewhere.
I think you can get something similar from the likes of Omron, Schneider etc. I've used a few of them over the years.
I think you give them too much credit on the electrical separation. On those china-thingys, i believe it's more "we have to have a slot for the terminals to mount up"-solution. Or do you think it was intentional ?
Digits 1, 3, 4, 5, 6, 7, 8, 9 on the display: 😊
Digit 2: 🤕
Never heard of Elitech, Only Eliwell. My biggest complain about these style of thermostats is the settingsmenu. All brands use differend button combination to get into setup mode. Sometimes you even have to enter a code wich is so annoying when you only want so set the temperature and you first have to find a manual for that specific thermostat.
I'm using a basic STC-1000 temperature controller to control the electric fan in my old car.
The original looks the same as the clone. The one you have is the refreshed version.
Is the differential temp setting in increments of 0.5 or 0.1? Or only 1.0?
I've just ordered one for the parts. A high quality transformer, 2 relays, a temp probe and a big bright display. (plus a few other bits). For under £15 it's a bargain. :)
I see the little transformers in the older (some still made) ATSC converter boxes. The PSU in those usually puts out 3.3V.
@@tubastuff Yeah, but this transformer is at least 12V, due to the 12V relays and 5V regulator it uses.
@@frankowalker4662 Mostly a matter windings, I'd think.
Getting support for elitech here in the US is hard. If I find them they get replaced with Danfoss controls.
16c ur room very chill
That's hot at this time of year.
Upsidedown A means V for Version. Without the line in the middle it would show an U as a readable character and not a V.
Never mind the custom display - these guys have their own custom _relays_...?
looks very useful, and decent quality
DIXELL are most common digital controllers I see on coolers and freezers.
Awesome big Clive
thought about doing a series on modbus devices and/or dmx?
I've featured DMX in the past.
You need a bottle of isopropyl in a bottle similar to your flux dispenser squeeze bottle. One with a syringe tip so you can practice technique and show everyone how easy the tamper proof security labels are to get off in tact, and to put back on with nobody else the wiser.
I have one on the bench for softening adhesives.
That the sort of thing I'd like to have to turn my bedroom fans on and off during the summer.
But is it worth spending the money on it for the 3 days of summer in the UK?
How long does it take to reverse engineer devices like this? I'm guessing at least an hour or two. Id like to see a full video someday reverse engineering a device like this just to see your workflow from start to finish.
It varies. Some are fast and others can take days.
How about long and medium range communications after EMP. CB FM mic etc. Anything that requires low or no infrastructure.
I wonder how many are just a weird thermometer and switch for the fridge.
The one I use has no need for any control but on/off since it never reached and temperature anyway.
Moar thermostats! ♥
I use the 'other' units to control a chest freezer to keep epoxy I sell cool (around 50f) and they go bad every 3-5 years, maybe I should get one of these for when the next one goes bad. It basically turns the freezer to a warm fridge. The epoxy I have wants to be cool but not too cold.
You shouldn't use a freezer as a fridge. It's not designed to do that.
Very inefficient.
If you know, they fail after 3 years, replace them after 2 years. No problems at all.
Does the relay fail from switching so often?
@@CyberlightFG It's not the freezer that fails, it's the little $15 controller. My last freezer lasted me 16 years (not bad for $170) and my current one is going on 8 years. This is for my business and it's an absolute necessity. The freezer only costs me around $30 a year in electricity since it's set at a higher temp and freezers don't spill out all the cold when you open them like a fridge (it's very common for people to turn them into fridges if they want to save on electricity). So not sure why you say it's not efficient. I store around $3k worth of a special epoxy in it on average and it's perfect for my use.
@@CyberlightFG Oh, it's the circuit board that tends to fail, not the relays. It only switches off and one around 6 times a day on average and maybe 10 times a day during the hottest summer days. Chest freezers are very efficient.