Imagine there are two rooms. Room 1 has a light bulb and a switch to turn in on/off, and room 2 as well has a light bulb and a switch to turn it on/off.

What I want to do is - connect a radio player to both switches, so that it would work as OR switch:

  • both switches are turned off - radio is off.
  • one of the switches is on - radio is on.
  • both switches are on - radio is on.

I think I successfully modelled how it would work using DC (I think):

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But would it work the same way if using AC power?


Based on received answer, I decided to simply use two separate radio devices. Each of them connected to corresponding bulb. Both radio devices are set to the same radio station, same volume and it gives desired result.


1 Answer 1


The best thing you can do is to use relays. Some things to note about your original idea that make it not workable:

  1. There is no such thing as a mains voltage AC OR gate.
  2. You mustn't* run a radio directly off a low current lighting circuit.

So you will need to use the lighting circuit to control a separate higher current (ring main) power source to the radio. The simplest circuit would be with two AC relays, one in parallel with each light, which feed power to the radio:


simulate this circuit – Schematic created using CircuitLab

*in most sensible countries


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