All, I have a Leslie Combo Preamp pedal that I use to connect musical instruments to a Leslie 147 Speaker.
The pedal has a Pilot Light in it that indicates if the Leslie 147 Speaker is rotating at "Fast" speed.
A foot switch on the pedal closed and opened the circuit that controlled speed. When the circuit was open, the Leslie spun "Fast" and when the circuit was closed, the Leslie spun "Slow".
There are two wires running to the foot switch. Right before that switch, the Pilot Light is located, connected to both wires that are running to the foot switch.
When the footswitch is closed, the current flows through the footswitch and not the pilot light, and the pilot light is not lit.
When the foot switch is open, the current flows to the pilot light and causes it to emit light.
Here's the strange thing that I need help with. I noticed that in Fast mode (with the pilot light lit from the open footswitch), an annoying noise would come out of the Leslie Speaker. I, just by chance, discovered that the Pilot Light was the source of this noise.
Some sources on-line talk about needing to ground pilot lights in electronics, or it can cause a 120Hz buzz.
Has anyone every heard of this before? Could someone explain to me what a Pilot Light is? Is it like a lightbulb, in that it acts as a resistor in a circuit?
Thanks, Joe