Electronic – Controlling Two Circuits with One Switch

circuit analysisswitches

I'm trying to build a circuit with multiple timers, each with an SPST output relay. I want to connect up my circuit so that if any of the timers reaches their set point, they turn on a beacon. It doesn't matter how many timers reach their set point, as long as one has I want the beacon to be on. Additionally each timer will turn on its own light when it reaches the set point.

I've drawn up a circuit, but have a question, is it possible to control two lights with one SPST switch? The simplest form of the circuit I'm visualizing is shown below:

(All the Lights and Beacon and Power Supplies are 12V)

enter image description here

The outsides (including the switches) are the timer circuit section, while the middle part is the beacon and its power supply.

I'm particularly confused about what happens in the red path. Would that be bad for the lights? Or turn them on before the timer switches close?

Best Answer

No real need for 3 power supplies here, so I simplified. Specific parts are circuit-lab defaults for the part type, not suggested part numbers.


simulate this circuit – Schematic created using CircuitLab

Add 2 diodes and I think you could make it work. As it stands either switch will turn on all three lamps. In the "red path" the voltage sources (as drawn) cancel, so no current should flow. The "beacon" needs a diode pointing at each switch which will permit it's current to flow through the switch, but prevent the current from the "individual timer" light on the opposite side from flowing to the switch beyond.