Why are two diodes used here


I'm following the wiring diagram for a digitech fs3x guitar pedal footswitch.

For the third SPST switch, it's wired from the other two switches connected by 2 diodes, both in the same direction. Can anyone explain why a single diode wouldn't work here (with both wires connected to it)

Schematic #1

Schematic #2

Best Answer

The two diodes are preventing a high potential on EITHER the Ring or Tip from generating a current flow into the Tip or Ring respectively, when none of the momentary switches are depressed. A single diode, say for example the diode between the Tip and the Up button, would not prevent a potential on Tip from generating a non-negligible current flow into the Ring when Ring was at a sufficiently lower potential than Tip. This potential would be approximated by the forward voltage drop of the N14002.