Description
These are "small signal fast switching diodes" which means they are often used in circuits with high frequency or fast pulses and have a very fast 'Reverse Recovery Time', typically a few nanoseconds or less.
In the pedal world, these are most frequently (and VERY frequently) used as clipping diodes, that is, as part of the circuit which chops off the peak part(s) of a sine wave, converting it to a square wave, which gives you a more overdriven or distortion-like sound. The amplitude of the resulting square wave depends on the forward voltage of the clipping diode, which in the case of the 1n4148, is typically around .7 volt. So in a symmetrical clipping circuit, the square wave would be +.7V to -.7V of the bias voltage at that section of the circuit.
 | 1n4148 Silicon Diode Download Datasheet PDF |
(actual brand may vary)
