Today’s China delivery was a relay board. I ordered two to try different manufacturers but this is a Songle relay rated for 10A at both DC and AC. Why I would use the relay for DC I’m not really sure but I hooked it up that way to test it. I would use the much simpler irlb8721 MOSFET arrangement by itself if I just wanted to drive DC loads since it is rated higher and is noiseless, provided I don’t need true isolation of the circuit.
So here is what I’ve got diagrammed out on Fritzing. The eventual goal is to drive under cabinet lighting using the relay, but this could also be done with MOSFET and ESP8266 arrangement. It’s a warmish day and I had an 80mm case fan sitting right in front of me, so I thought I’d hook it up.
There are a couple of notable things:
- The ESP8266 only puts out 12 mA from the pins, and from what I gathered, the relay draws about 70-80 mA so that’s a no-no to try to use the ESP on the relay alone.
- The relay with MOSFET needs to be set in high level trigger mode with the jumper.
- It is probably not the best idea to drive the MOSFET from Vcc through the FTDI cable that I’m using to program the ESP8266.