He mentioned a site about relay ... switch logic (that is, two switches in series are an AND gate and two in parallel are an OR gate), it isn’t the only way. If you are wiring a large circuit ...

A common solution we’ve seen applied is to connect a relay in parallel to all the buttons ... A simple test circuit (using a switch to provide the current needed instead of a microcontroller ...

An RC circuit ... reduce the relay’s driving voltage without relying on unused contacts or sophisticated circuitry. All we do is add two common parts: a resistor and capacitor in parallel.