XOR light switch with two switches and a relay

Question

I have just created a circuit which uses an SPDT relay to switch a light on or off whenever i double clap. It works fine with my desk lamp, so i thought it would be nice to add it to my wall mounted lamp, which has two switches in XOR configuration. My goal is to be able to toggle the light with the relay as well.

My only idea is so far to replace one of the switches with the relay, but i wouldn't like to go that way. Has anyone got an idea how could i wire the switches and the SPDT relay together the way I would like it to work?

Answer 1

It sounds like you have what we call a "three-way" switch arrangement. That is two SPDT switches. You can replace one of those switches with the SPDT relay (conformance with whatever your local electrical codes require is not considered in this answer).

If you wish to retain both the two existing switches, it cannot be done with a SPDT relay- you will need a DPDT relay or two SPDT relays wired to work together.

In this case the DPDT relay is wired as a reversing relay and replaces the "4-way" switch in the above diagram (from here).

^{simulate this circuit – Schematic created using CircuitLab}