Hopefully helpful idea

[Farace]

I had a thought today that seemed useful and I thought I'd share it. The problem was how to know when working on electrical whether lights have gone on or not when one is not in a position to see them or doesn't want to keep getting out from, say, under the car to look. We have a one-year-old at home, so I can't count on my wife being able to stand around and let me know if lights have gone on.

I remembered that when working alone on house wiring the easiest way to know if you've shut off the right breaker when you're in the basement and the circuit is upstairs is to plug a radio into the circuit you want to shut off. When the sound stops, you've found the right breaker.

I decided that what I'll do is to take the base from a blown bulb, remove the glass, and wire a 12-volt buzzer to the electrodes. I'll likely need to glue a dowel or something like that into the base so that there's enough to hold onto to remove it from the socket. This way, I should be able to plug the buzzer into my nonworking socket for, say, the reverse lights, and then be able to tell from underneath the car if I'm fiddling with wires at the transmission whether I've brought the circuit back to life, and not have to crawl back out every time I want to check. Maybe this is a common thing, but I'd never heard of it, so I thought I'd pass it along in case it's useful.