HiLetgo 2pcs W1209 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
$8.49
Price: $8.49
(as of Nov 10, 2025 21:19:37 UTC – Details)
Specifications:
Model: W1209
Dimensions: 48.5 * 40mm
Temperature Control mode: ON / OFF
Temperature Range :-50 – 110 degree centigrade
Resolution: When temperature is 0.1 degree, the resolution is -9.9~99.9, other temperature segment is 1 degree.
Control Accuracy: 0.1 degree
Hysteresis Accuracy: 0.1 degree
Refresh Rate: 0.5s
High Temperature Protection 0 – 110 degree centigrade
Supply Voltage: DC 12V
Static Current: Less than 35MA, attract current less than 65MA
Output Voltage: DC 12V
Output Power: 20A relay
Measurement Input: NTC (10K 0.5%) Waterproof Sensor
Environmental Requirements: -10 – 60 degree centigrade; Humidity 20% – 85%
Instructions for use:
Connect the power supply and equipment, the measuring temperature is displayed,
press the “SET” button, press ” + or – ” to set the desired temperature (long press ” + or – ” to quickly increase or decrease),
press “SET” to confirm the setting and return, controller automatically performs the relay ON/OFF.
the thermostat output is 10A relay, meet a variety of high-power loads. LED Indicator: LED off indicates the relay off; Lighting, indicates the relay is closed.
Digital LED Tubes: “LL” indicates sensor open, “HH” indicates overrange, the relay will be forcibly disconnected; “—” indicates high temperature alarm
Long press the “SET” button to enter the main menu settings,
press ” + or – ” to switching between P0-P6,
then long press “SET” or 10 seconds without keystrokes to confirm the setting and return.
Package Included:
2*W1209 12V DC Digital Temperature Controller Board
100% complete machine patch, wave soldering, stable performance, good consistency.
Embedded CPU chip (MCU), more intelligent, lower power consumption.
Automatic power set memory (MCU built-in EEPROM memory unit).
Control accuracy of 0.1 degrees Celsius. Have been tested for stability, consistency and reliability.
Tips: – long press set to get menu, starts at P0 – press +/- to get next P-parameter – press set to choose that parameter – press +/- to select the value you want for that parameter – press set to accept it – long press +/- = reset to default – power-out does reset to default – default temp set is 34.5C
James –
Air Conditioning Freezing Fixed!
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?
JessMess –
Works well
I used these to turn a fan on/off in my chicken coop. Solar charges the battery, the battery powers the switch and fan… a couple months now and everything is still working as expected. I spliced the temperature sensor wire to make it longer so i could put the switch in the battery box, but that was an easy task
Zax –
Cheap, effective, no instructions
I purchased this product for a little side project. I wanted to add a 12v fan to cool the charging transformer in a battery backup when it is charging on commercial power, but didn’t want the fan to run 24×7. The UPS is no longer charging the small 7AH 12V batteries, but rather two 90AH 12V batteries.Installation of the device in the UPS case was pretty simple, but wiring and configuration was a different challenge since this product comes with absolutely no documentation. Keep in mind that this unit only deals with Celsius. If you want to know Fahrenheit, you’ll need to convert it.Fortunately, some other reviews here have links to instructions and wiring diagrams.To wire it for 12V power to the controller board **AND** to the load device (fan in my case), do the following:1. Connect the 12V power source to the +12V terminal2. Run a short jumper wire from the +12V terminal to the K1 terminal, tighten down both +12V and K1 terminals.3. On the 12V device, (fan in my case), connect the positive power wire to the K0 terminal and tighten the terminal4. On the 12V device, (fan in my case), connect the negative return wire to the GND terminal. Also connect the negative return wire from the main power source to the GND terminal. Tighten down the terminal.To program the device for running a **cooling** fan like I did, do the following:1. Short press “SET” button one quick time and set the desired “turn off” temperature with the “+ or -” buttons. This is the temperature that your fan will turn off once reached. Once you have your “off” temperature selected, press the “SET” button again.This should get you going. If you set the temperature to 30C, the default swing temperature is 2C. This means that the temperature probe must get to 32C before the fan will turn on. The fan will run until the thermal probe drops back to 30C, then shut off.If you want to change the default swing temperature from 2C, do the following:1. Long press “SET” button until P0 shows on the screen. Press the + button until P1 is displayed. Short press “SET” button to modify that value. You should see “2” which is the current default setting. Press “+ or -” until the desired temperature is reached, then short press “SET” button again to set the new value.If the main “off” temperature is set to 30C like the above example, and you set P1 to 10, then the thermal probe would have to get to 40C before the fan kicks on. The fan would then run until the thermal probe reaches 30C before shutting off.
Graphic Fusion –
Fiddly to assemble, but nice controller!
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.
antonio –
Control de temperatura de un Inversor Vcc/Vac.
Amazon Customer –
Bought these (only in fact needed one) to control solar powered ventilation fans in my greenhouse. Can be configured to operate in cooling (on when set temperature exceeded) or heating (on when below set temperature). There’s a couple of degrees hysteresis so it won’t oscillate too much. The LEDs show the current temperature and it seems fairly accurate. The temperature probe supplied has a reasonably long lead and is potted into a metal cap, making it waterproof (the board itself will of course need protecting in a box).Configuration is simple, albeit a bit tricky to figure at the start I found. It essentially comes down to up and down buttons to set the trigger temperature. The settings are non-volatile so survive power loss.Was a bit concerned about the current drain given I’m using it in a solar/battery environment. However, even though it has pretty bright LEDs they have minimal drain on my small Li-Ion pack (not enough to discharge it over night anyway).
Lorenzo S. –
Bel prodotto, un termometro con funzione di termostato, anzi due. Molte le impostazioni e regolazioni disponibili se si ha la pazienza di leggere le istruzioni, non fornite dal venditore, ma reperibili in rete. In sintesi, possibilità di impostare la temperatura soglia di attivazione del rele con possibilità di scegliere se al crescere oppure al decrescere della temperatura. Possibilità di fissare la tolleranza o inerzia in gradi per lo scatto del trigger. Sulla durata non posso ancora dare giudizi. Quindi parte elettronica ok. Devo essere invece critico per quanto riguarda il layout dei componenti, posizionati a mio parere senza molto criterio. Display e pulsanti risultano infossati rispetto al rele e alla morsettiera rendendo così impossibile l’inserimento di un pannello frontale. Prezzo al momento insuperabile. Se interessa posso riportare istruzioni, fate sapere in commenti.
Daniel Cozzolino –
Works exactly as specified. I use it to control an electronic solenoid connected to a tap which turns on a mister in my greenhouse if it gets too hot. Easy to program too
Erwin Adam –
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.