HiLetgo 2pcs W1209 with Case 12V DC Digital Temperature Controller Board Micro Digital Thermostat -50-110°C Electronic Temperature Temp Control Module Switch with 10A One-Channel Relay and Waterproof

Used these on a jury rigged device for melting chocolate in a water bath. They were calibrated better than I assumed they would be, being very close to other thermometers I have. Unless you're doing something with extreme precision, these will do the trick. The documentation is nonexistent when you buy them, you're going to need to find a manual online. The way the hysteresis works is the thermostat will turn on, bring it up to temp, then turn off at the temp, then wait until x degrees (hysteresis setting) below the target temp to turn on again. In cooling mode it will do the opposite, waiting until you're x degrees above the target temp to turn on. Also be aware, these are in celsius, and there is no way to change that. That shouldn't be a problem for any DIYer interested in this though. One other thing: I believe the relay on the device is rated for 10A. Maybe less if I'm misremembering. Just don't even bother with it. Get another more solidly built relay, and use the small controller relay to activate that one. No reason to risk putting lots of current through this thing. Final thing: the relay is a mechanical one that clicks. So if you want to do some sort of higher precision / frequency stuff where you're turning it on and off multiple times a minute, just get an actual PID controller.

I have a home made cabinet for my CNC router. There is a compartment for the computer, but it doesn't have much air circulation. The other day I noticed the temperature was quite high in the cabinet and possibly a contributing factor for a recent hard drive failure. I wanted to add a fan to circulate air, but since the computer goes in to sleep mode and doesn't generate much heat when it's not being used, I didn't want something that ran all the time. With this gizmo and a 12V fan, I was able to set it up so the fan only runs when the temperature in the cabinet exceeds a certain amount. So far it seems to be working great. I have it set to come on at 32C and go off at 30C, and it's been been right in that range each time I've noticed the fan running. Set up was easy. I already had a 12V supply available in the cabinet, so all I had to do was hook up the power, insert the K0 and K1 ports inline with the positive lead of the 12V going to the fan, and drop the sensor in the cabinet. As I recall the default settings were what I needed, except maybe changing the temperature range. I opted for the case and that was worth the extra 60 cents. I could have laser cut my own, but it probably would have cost me 60 cents worth of material and certainly more than that in time. The only complaint about the case is that is doesn't provide any holes to mount it to anything unless you want to use the same holes used to hold the case together. No big deal - some double sided foam tape got the job done. Definitely worth it for less than $5 each.

Not a huge fan of the small plastic enclosure that come with the parts. It is finicky and not all that strong. I had originally purchased the enclosure so I wouldn't have to take the time to make one, but ended up doing so anyways. Boards themselves functioned just fine.

While there are plenty of professional fixes for central AC that freezes up, sometimes it's just a combination bad duct airflow, low outside temp, and/or too low thermostat set. Obviously you should make sure you aren't low on refrigerant or the air filter is dirty, but if you have old ducting or a miss-sized unit, it just happens sometimes (especially fall and spring). If your wallet doesn't mind the thousands of dollars to get a new AC installed or otherwise remedied, skip this. For the rest of us, this little gem you just provide it 12V (find an old wall wart, or buy one for a few bucks), cut one of the signal wires from the furnace to the AC (usually 2 of them, carrying low voltage AC, doesn't matter which one you cut), strip the ends on both sides of the cut and put them into the two relay legs (K0 K1), and then tape the temp probe to the copper coolant-in line. Set the setpoint to somewhere a little above freezing (5C or so), set P0 to "C" for cooling, and then set P5 (restart time) to 5 minutes. Now, if the line approaches freezing, it will cut out the AC unit outside while the furnace/air-handler fan still blows air over the too-cold coils warming them up. The restart delay prevents short-cycling the AC. Cheap, easy, works. Will mask a dirty air filter, but you're changing that on a regular schedule, right?

I give it 5 stars because I'm very satisfied with the product. It's precise and well-conceived. It's got a few rough edges, though. (I decided not to deduct a star, because the everything else is so good.) 1. Very clever and attractive little plastic case. However, it requires assembly, which takes a bit of time. It is made of 6 precision-cut panels with protective film that you need to peel off. They insert together with tabs. Getting all the tabs in the holes is a fiddly process. If you want the case to be completely flat for mounting, you might want to remove a bit of the tab material before assembling, as the tabs stick out ver slightly (fraction of a mm) on the opposite sides of the holes. 2. Some of the leads on the bottom of the board are a bit too long for the spacers provided, so you will need to trim them before mounting it onto the bottom panel of the case. 3. I don't like the screw terminals. It's hard to insert wires into them. I have a rather stiff 18AWG wire that I used, just because I could push it into the terminal. Forget using any finely stranded wire, unless you use a (small) ferrule. 4. The two boards I received disagree by 0.8 deg C. It's not a deal-breaker by any means. 5. Setting the "on" temperature is very intuitive, but there are no instructions. Press (do not hold) the set button, and then set the temp with the +/- buttons. When you hold the set button, you end up in some mode to select different programs, without any idea what those are. (I think they set different hysteresis values.) 6. The relay is pitched as 20A. However, that's the rating for 15VDC. The 120VAC rating is 10A. The 240VAC ratting is 5A. Other than that, the board is very snappy and precise, programmable to 0.1 degC increments. The temperature probes respond quickly.

NO DOCUMENTATION!!! All they had to do was provide a link to the full instructions like: W1209 12V -50° to 110°C Digital Thermostat Temperature Controller Module Installation and Operating Instructions Search the above to find a great set of instructions including the table I pasted below. Putting it together was a bit of a pain, but for the price, totally worth it. The case is decent but DOES NOT HOLD UP TO Locktite thread locker. For whatever reason, made the edges where the bolts go through break off, 3 of four broke. Some good comments helped, however, didn't see anything for the P values, which I found elsewhere. Copy and paste these in a spreadsheet and the tabs will fix the alignment: Code Description Setting Range Default P0 Heating/Cooling Mode H/C C P1 Hysteresis (Return difference) Degrees 0.1C to 40C 2C P2 Set Upper Temperature Limit (Degrees) -50C to 110C 110C P3 Set Lower Temperature Limit (Degrees) -50C to 110C -50C P4 Temperature Offset Correction (Calibration) Degrees -15C to +15C 0 P5 Trigger Delay Start (Minutes) 0-10 Minutes 0 Once I figured out how to properly configure, seemed to work fine. Connected some 12V heat strips (This is where the documentation mentioned in the first paragraphs really helped), and the unit kicked on and the heat strips heated, no smoke, no issues, when the temp rose, the relay shut off and the heat pads did too. So value for the money is excellent, I'd buy this again, probably will. Had they made it easy and just given great instructions, I would have rated it a 5.

Another reviewer mentioned that the 12v to 5F dc regulator IC,( AZM1117 ?) is incorrectly applied. I have also confirmed this issue. I not only traced the pc lines to confirm this misapplication, but I also measured that +5V bias input to the controller IC (the output of the 5V regulator) varies as the +12V input varies. The output pin of the the regulator IC should be a constant 5V (or possibly even a constant 3V since I don't have a part numbers for the controller or dc regulator). I also noticed that the IC regulator is rotated 180 degrees on the parts I shown on the photograph illustration. I also observe that the temperature controller appears to function with an input voltage on the +12V input pin as low as 3.5V and as high as 12.5V, but with very low input voltages, it is iffy that the relay will function correctly. I definitely DON'T RECOMMEND using this product when high reliability is important. I am annoyed that the product specifications does not have a recommended operating range for the input voltage. I wonder why?/S. I am especially concerned with applications that are powered from a Lithium battery that can have a charging voltage as high as 14.6V. BTW, I am an power electronics design engineer with 40 years of experience. You have been warned!

I bought 2 sets of these from different vendors, but they were the same exact units. There were no instructions and the wiring took some time to figure out. The first ones that I received worked fine during testing, but when wiring permanently (the same way that testing was done) the small CPU chip burned up. This happened to both units. I then bought another set from another vendor, thinking I may have better results. I did not. The second set I received had the same issue. On the first unit, when jumping the 12V+ lead to K1 terminal and applying power the cpu chip burned up immediately. I tried to wire the 2nd unit without the 12v jumper to at least power the unit, and it turns out that it arrived with the circuit board cracked in half. The 2nd case was also damaged. These units come in anti-static plastic packaging and no box, so they can be easily damaged during shipping. One of mine had a hairline crack that I only noticed after wasting time assembling, wiring, and troubleshooting. The only reason for ANY stars were the low cost and the fact that I am assuming when they are wired correctly, they seem to work as intended. Some simple wiring diagrams, instructions, and a box for shipping would likely turn this into a 5 star product. Also...FYI... I did plenty of homework after ruining the first 2 units by searching the model #. When the 2nd set arrived I was prepared and thought I knew what to do. After 4 units were thrown in the garbage, I cannot endorse these. Like stated above...some simple instructions and better packaging would make all the difference here.

I used this as a fan controller for my motorcycle. I put the sensor into the radiator fins and dialed in the temperature I wanted to see on the temp gauge. The fan comes on and goes off precisely and crisply compared to the thermo switch that was impossible to find for an older bike. It now starts the fan smartly as opposed to groaning to life with the thermo switch. Just connect the device (+) source power to the running light circuit which comes on when the engine is running. For the fan, provide frame ground, and positive from battery, then through 10A fuse, then through switched relay onboard the device to the fan positive. The programming is simple if you google the device specs on YouTube.

I only got one in the package. Was supposed to come with two. And waterproof lol. It should come with a tube of silicone if you’re gonna try to say it’s waterproof cause that what you’ll need to use. I’ve used these before and they work good is the only reason I didn’t send it back.

When it gets to 0 degrees, it shows HHH or LLL and shuts on and off, over and over again. This is bad for a compressor that is trying to control a FREEZER or refrigerator.