An 'impulse' or 'ratchet' relay and two momentary push button switches is all that is required.

An impulse relay changes state with one push of the button and reverts with the next push.

The schematic is as follows:



Here's an animation, courtesy Homofaciens.de, that gives an idea of how the impulse relay works.

Nandu.

 

Have you not heard the old joke about coming home to find an aeroplane at the top of your stairs?
Must have left the landing light on. . .

Ouch. I am pretty sure you violated the terms of service with that. If not, it should be a violation.
Checking, I can’t find anything about extremely terrible puns in the ToS, an oversight to be sure.

 

An 'impulse' or 'ratchet' relay and two momentary push button switches is all that is required.

True, but does not comply with the requirements set out by the TS in post #1.

 

True, but does not comply with the requirements set out by the TS in post #1.

Hi sghioto,

I thank you for the feedback.

Here's my version that, I do hope, complies with the OPs requirement.



Nandu.

 

Here's my version that, I do hope, complies with the OPs requirement.

It does. That's the correct way to simulate a 3 way switch using 2 DPDT relays. Not practical but it does work.