Build Your Own Clone Message Board

What does the momentary switch do? It doesnt seem to have any effect in my circuit? Building this for a guy on here so I have no clue what the pedal is supposed to do. Bypass works fine, vibrato works fine. Just this momentary switch, I dont know what it does?

When the ramp toggle switch is up, the momentary footswitch brings vibrato in. How quickly the vibrato is applied depends on where the rise time knob is set. When the ramp toggle is off, it's a normal true bypass circuit.