Electronic circuit question
Hello all,
I am working on some annunciators which will be driven by a Phidget LED 64 board. I was thinking that it would be really cool to have annunciators that have an 'on' state and 'off state. For example, bright green when on, and dull orange when available but off. That way you know where indicators are, and it doubles as a fail safe (i.e. no light = circuit failure)
Is there any way to do this electronically? Basically I'll draw power from the phidget board to light the green LEDs. But when the output is switched off, I'd like a circuit that detects this and applies power to the orange LED. I'm pretty sure this is all possible, but have no idea where to start. Something tells me that transistors are involved in this somewhere, but I'm guessing.
Thank you
Paul