SparkFun Forums 

Where electronics enthusiasts find answers.

Have questions about a SparkFun product or board? This is the place to be.
By thirtywest
#196376
Hi all,

I've got an adafruit audio fx board that takes around 3.3VDC input triggers. I have several trigger inputs that I'd like to source from for this.

1. doorbell button
2. PIR sensors

The doorbell is 24VAC (or close to it), so simply tying those contacts to the sound board won't work. I thought about a full-wave rectifier + DC step down (12 to 3.3) might work, but it sounds overly complex for pushing a doorbell.

The PIR sensors appear straightforward: use the output to the light or PIR "trigger" to close the circuit to the sound board. Except, the voltage might be too high--so we're down to lowering voltage again.

I'm looking at opto-couplers too--or even a mechanical relay to run off the doorbell. Any suggestions would be great. I'm new at this but have time to get educated.