Teyleten Robot DC 1 Channel Optocoupler 3V/3.3V Relay High Level Driver Module Isolated Drive Control Board 3V/3.3V Relay Module for Arduino (Pack of 5)

Can be used from a ESP32 system which has 3.3V logic without any additional circuitry. Has screw terminal blocks for both sides of the relay making it easy to integrate with microcontroller board. Has a red LED that lights when the relay is activated, giving good operational feedback.Only niggle is that the screw holes are a bit small. i had to enlarge them with a file to fit normal sized standoff screws.

There are a lot of reviews for these clearly written by people using them in ways they are not intended to be used.I am using these to trigger different animatronics from an ESP32. I have 3 of them run in parallel with a 3v LED at the end of the chain. I am powering them from the ESP32's 3V3 pin. I am using a GPIO as the trigger. The ESP32, connected via usb to a computer, still provides enough amperage to trigger all 3 at the same time in addition to powering the LED.The relays support 250V@30A on the output side ONLY. Some people mentioning theirs caught on fire, but clearly are running voltage to the wrong rails.There's no documentation on the jumpers, but basically they are ground and VCC. I am not sure why they would be there, but I guess you could use them as headers to not use the screw terminals? this seems silly though as IN would still need to use the screw terminal.Overall these work great for my project.

Awsome little rely boards. I am using them with an ESP32 and they are switching 24 VAC for zone valves and to trigger my boiler's circulator pump and burner. My only complaint is the screw holes are too small and very close to the terminal blocks, however, they still deserve 5 stars. Some have mentioned issues powering these. They are happiest receiving 5 volts to the VCC pin and ground and they have no issues with the 3.3 volt signal from the esp32. Just something to keep in mind when using these. I have a buck converter that reduces the 24 Volts AC to 5 volts DC with a 2 Amp capacity. I am running 10 sensors, 2 ESP32s, a SSR and 5 of these relays off a single converter so power draw isn't an issue. The boards are well made and the components are mounted very well. The indicator LED is nice to have and the relays have a solid and satisfying click when they are engaged.

I’m using 2 of these to control a gas heater and a gas water heater with a Raspberry Pi 4. The 3.3v GPIO pins reliably open and close the relays. Homebridge and a bit of scripting and I can now use Siri and HomeKit to control decades-old home devices! It sounds like ESP and other lower-power devices sometimes have trouble driving enough amperage, but it seems like the Pi 4 works. The only downside is that you have to buy sets of 5, and there is only an LED to indicate whether the relay is open or closed (other similar modules have an additional power LED).

These 3.3V relay modules WORK GREAT!Using this module with my Raspberry Pi Pico 2W board, a 3.3V micro.Sharing a schematic I found that documents the two on-board jumpers

I'm using these to control the led grow light in a custom hydroponic set up I made. They allow me to remotely and programmatically switch on and off a grow light with my raspberry pi. I made a custom box for it all and an very pleased.

These are great if you wish to switch using 3V3. So many others are 5V or higher. I wish the board was a bit smaller, but it seems about as small as it can be made.

These don't fit the wires you'd typically use in a Arduino project because they are too small but it's really easy to just desolder the connecter and solder your wires directly.