I have an RGB LED that I'd like to change from green to red when a circuit is completed. While I know this is very simple with tools like an Arduino, I'd love to not use a microcontroller. Would it be possible using basic components (which can certainly include transistors, diodes or even common ICs like a 555 timer) to achieve this? If so - how would I connect the components?
Clarification: I'm using a common anode RGB LED (a lead for each color plus ground - four in total). I'd like to have it be green when a switch somewhere in the circuit is open (not connected) and red when the switch is closed. The switch is not connected to anything else.