DC 5V Relay Module 1-Channel Relay Switch with Optocoupler Isolation High/Low Level Trigger, Pack of 10

It's well thought out. It's easy to control the relay from a low power processor pin - just a couple mA will do the job. You can select whether the relay is triggered by a Vcc or ground signal, and the relay itself is SPDT. It works fine at 5v. The board has a power LED, which is annoying because power drain is an issue with battery circuits, and a separate LED which lights when the relay is energized, which is more acceptable. They can be removed. The relay itself is small and won't switch high currents at high voltages, but you can easily use it to control small lights, little motors or a larger relay. Pleased.

Well documented above, rare for such DIY parts. No soldering required (for those who don't like that). Very versatile, you can reverse the input logic with the jumper. I also like that the output terminal provide both NO (Normally Open) and NC (Normally closed) so it can adapt to your application when you lose power to the boards with NO or NC. I find the green power LED very bright. I might remove it from the board. The red LED is just bright enough in my opinion. Very well packaged, individually wrapped, they look like candies! Works well driving and powering the relay with a Wemos D1 mini with the D6 pin (digital 6). I have flashed the Wemos with Tasmota. WOULD BE A KILLER BOARD IF: it was combined with a transformer and regulator so it could produce 5V from the OUTPUT lines. I mean I'm mostly driving 120V on the relay output side. If the board could take Line+Neutral, then you could power the relay board and the Wemos micro without an external power supply. Essentially, creating a smaller Sonoff. Martin Politick January 2020.

Fantastic set of 5v relays for the price. Warmth is very manageable. I’ve ran 110v through one for a dehumidifier that basically ran 20 hours a day for a month and was safe to hold my hand for as long as I wanted on it. Been moving more and more to esp devices. And with a recent home assistant setup I have gone nuts with esps. These 5v relays work fantastic and reliable at 3.3 volts as well!

Perfect for isolating the relay switched load from other circuitry. Works as expected in my various applications.

As a hobby project I have been using these relays to build smart extension cords controlled by ESP8266 chips, and for the most part they have worked quite well, but this morning I discovered one was no longer stopping current flow when the relay was turned off. After investigating I found the NO and COM terminals had melted together due to heating, see the first picture. This relay was being used to control a 1500W space heater and I do not have solid data on runtime, but I would estimate it worked for roughly 30 hours, so if you are powering something lesser I would not be too concerned. However after enough time with such a significant load the terminals have failed completed. On the upside, I ripped the terminal block off the end and tested the relay itself to verify it was still working! If you are looking to control something so powerful, maybe look at just getting this type relay without an accompanying board and put your own circuitry in front of the control side, but at $1.5 for these versus around $0.8 for just the relay, which would require additional effort to put circuitry in front of the control side, this is a pretty solid purchase, and you could always just bypass the terminal to connect your wires to the relay's contacts directly. I intend to do exactly that with the pictured relay and put it back to work!

I bought this accidentally, but it's a great purchase nonetheless. I've used only one so far, and it works fine.

Works great, simple to use. I use NO and NC sides. I have not run more than about 5 amps through them. For the price they cannot be beat.

Works well, easy to use, HC-SR501 PIR Motion Sensor will drive relay directly (no arduino, no transistor, no optocoupler)

I’ve used several of these Valefod 5 V relay modules and love them. They’re simple, consistent, and the optocoupler isolation keeps my microcontrollers safe. The board layout is clean, screw terminals hold wires tightly, and the indicator LED makes debugging easy. Triggering from an ESP32 or Arduino works flawlessly, and the relay coil barely warms up even after hours of operation. For the price, these are excellent quality — reliable, compact, and ideal for small control projects.

These relays work exactly as they should. I've used them for switching on a 3D printer remotely from an octopi (raspberry Pi) via IO pins, and to turn on high powered-UV lamps from an AVR/arduino. Great for automating 120V devices around the house.

It works fine, but a bit more instruction would be nice

Works great with esphome/esp32. esp32 can directly turn the relay on/off & relay board can be powered using usb power.

Great little devices, beats just buying the relays from another website because the PCBs they come in are so configurable (like normally closed, or normally open, trigger high/low, etc.) and have terminal blocks that make it easy to rapidly prototype. If you're putting these in permanent projects like I do, I recommend hot gluing your wires in. I've had some problems with the terminal blocks not latching properly in the past