I have two audio effects units that have foot switch
operated bypass functions, which use momentary
switches. I want to add an led indicator to show when the effect
is on or off. Can anyone suggest possible solution how to
configure this. (would be all so easy if switches were latching!)

 

Hello,

Do you have the schematics of those effect boxes?
If so we can have a look how to implement the leds.

Greetings,
Bertus

 

I don't see any problems if you can find out what voltage and current is flowing trough those switches. Adding a led it would be mostly mechanical. what you need to lite a LED is 1.8v for red and 10-20ma.
found out first what you have then I will help.