Tremolo and Reverb footpedal fender twin

these just short the tip of the RCA jack to ground

I just threw one together for my '75 twin, and when I switch the tremolo on and off there is a loud pop if the reverb is engaged.

Does anyone know if there is anything else in the pedal besides switches? Should I not have them connected to the same ground point? (even though they are grounded together in the amp...)

if anyone has built a pedal like this before please let me know how you eliminated this noise

thanks!

The switch could be funky, you might wanna check that out first. Also, it could be time to re-cap that tremolo circuit. Sure couldn't hurt and it usually makes the tremolo sound deeper and fuller.
No there is nothing else in there but the on/off switch.
Mike Fuller has been trolling around here, maybe he has some advice on the subject?