Make your own free website on
Doorbell for the deaf by I. Anderson.

This circuit, which I have found very sucessful, may be of interest to another elderly member who, like me, is hard of heraing.

Doorbell Circuit Diagram

I used two zero-crossing optocoupled triacs, one for the living room light (wired across the light switch) and one for the bell. Both perform very well, even at 11V AC for the bell, and the CMOS 4001 Quad 2-input NOR Gate drives both without problems. At first the circuit was randomly triggered by mains spikes picked up by the lead from the bell push to pin 2 of IC2, but this was eliminated by connecting a 100nF ceramic capacitor across R2. I also found tgat the 470nF timing capacitor C1 gave rather a long ring, so I changed it to 100nF, which was much better. I imagine a CMOS 4017 10-line decade counter would work well instead of the CMOS 4024 7-bit (128) ripple counter, and be more flexible, but I haven't tried it.