HiLetgo 2pcs 5V One Channel Relay Module Relay Switch with OPTO Isolation High Low Level Trigger

As long as you have a multimeter this is one of the most reliable relay switches I have used. I have it sealed in a large shrink-wrap tube filled with hot glue freely mounted to the side of my bike.

As per usual another solid product from HiLetgo. I have been ordering from them since 2020 quite often. It started out because of the price and reviews mostly good. Now I always try and use this company from resistors to diodes to relays ect. I've only received 1 bad ESP32 and all it took was a soldering iron and 30 seconds and I was on my way. I ordered their relays 3 years ago and the same ones are going strong. So; I ordered these and wasn't let down upon opening.

Relay worked exactly as predicted, came with great tech specs

I bought this relay module for use with microcontroller output, have less than 10mA to work with. It works, I deducted one star for no datasheet or diagram available. It IS possible to completely isolate the two sides of circuit. Remove the jumper completely. For your microcontroller side, you will attach to the center pin of jumper and IN pin. These two pins connect to the input pins of the optocoupler & 1kOhm resistor. The resistor drops 5v to 5mA current. You can use these two pins in a sinking or sourcing manner, but the polarity must be correct as the opto is a diode on the input. Supply a separate 5v supply to power pins DC+ and DC- to power transistor & relay coil. The relay contacts are isolated from everything else, so you can switch AC or DC at a different voltage using COM and either NO or NC contacts. (NO = normally open, NC = normally closed)

I connected the unit to a Raspberry Pi Zero 2W, in order to turn on the 120v main for a UV LED outdoor light project. The DC+ went to the 5v pin (Pin 4) The DC- went to a ground pin (Pin 6) The IN went to GPIO4 (pin 7) The COM went to the Black (HOT) line on the 120v plug. The NO went to the Brown (LOAD) wire on my voltage converter. The 120v Plug's White (Neutral) line is connected to the blue line on the voltage converter. A python script on the Raspberry Pi runs every 5 minutes during the hours between 6pm and midnight via the cron function. The script turns on the converter for 2 minutes and then lets the LEDs cool for 3. Voltage converter link: https://www.amazon.com/dp/B01N5SJ72Y

Wiring was super intuitive and everything just worked. I was able to power, ground and provide signal all from Arduino and then pull 12V DC from a 4A dedicated power source and connect it directly to the 12V DC magnet when the relay receives a signal. Perfect solution for my secret bookcase door project! Only note was that the relay screws needed the perfect sized screw driver because it felt like it was going to strip with the one little screwdriver I use for everything so I had to get a new small screwdriver kit and then i was able to repeatedly install and change configurations on this board without any problem.

compact and works as stated

With the caveat that its only been running a few hours, seems good so far. Very simple and easy to connect to my 3.3 Volt Arduino Nano 33. I used 5 volts to power the relay and a 3.3v pin for signal and that seems to work just fine. If I wanted to nitpick, it would be nice if it had solder holes and not just screw terminals. Screws are good for my breadboard prototype; not so much on my final design. So I will try to remove the screw terminals by de-soldering.

Connected this relay to Shelly Uni to be able to opens my front door remotely. Works really well

No es adecuado a lo que necesito.