Hello folks,

I have a circuit that uses a DPDT switch to choose two possible audio paths. I would like to add an LED(s) to show which path has been chosen. Yes, I could use a 3PDT switch, but I would rather not. I cannot modify the wiring of the switch, as the two paths (+ and - of a balanced microphone running phantom power) must be switched as-is.

The solution must not colour the audio in any way.

Any thoughts would be most appreciated

 

You can try a resistor on one path going to the LED and completing circuit Since the circuit is using phantom power it should light. It may however interfere with the audio. YMMV

Hello folks,

I have a circuit that uses a DPDT switch to choose two possible audio paths. I would like to add an LED(s) to show which path has been chosen. Yes, I could use a 3PDT switch, but I would rather not. I cannot modify the wiring of the switch, as the two paths (+ and - of a balanced microphone running phantom power) must be switched as-is.

Any thoughts would be most appreciated

 

The LEDs could be driven by opamps. Since opamps have high input impedence, they should not interfere with fidelity.

A modification of the "bar graph generator" in this tutorial should work: http://www.allaboutcircuits.com/vol_3/chpt_8/3.html

Note that the LEDs would only light when a signal was present. One would still have to look at the switch when no input was present.

 

how about using 2 DPDT. the other pole to take care of the audio path and the other pole to power up your LED. that way there is no audio interference.

moz

 

Thanks people!! I'm thinking I might "merge" your thoughts and use 2 small DPDT relays controlled by a single SPST pushbutton.