Review on KNACRO SLA-05VDC-SL-C 1-Channel Relay Module - DC 5V 10A with Optocoupler Isolation, High/Low-Level Support by Kevin Apriando

I have used this in automotive applications to activate a 12v LED from a TTL source in my aftermarket cruise control. The low level trigger works great even when hooking up a vampire to the cruise control LED line! The output connects the factory LED to ground via a resistor and lights up as if the car had cruise control fitted - finally I can see what can be retrofitted with cruise control instead of just guessing! I wish the documentation was a bit better, but otherwise everything was easy to connect and control. This is the third module from the end in the picture. A NOTICE. I isolated the 5V+/- power supply from the 12V ground, but I didn't need input protection - it worked right away!