We can see this type of effect is applied in guitar effect pedals.

Tremolo effect is produced if we modulate the amplitude of an audio signal.

The shape of modulating signal can vary from square wave, sawtooth, or sine.

This guitar effect circuit is basically a damped oscillator that is set slightly below its critical oscillation point.

The oscillator part is constructed by feeding back the output signal through a bandpass circuit, with the.

This circuit doesnt produce very good sound output, but it has very stable amplitudevolume.

This compressor circuit design is unique since it uses base current control for manipulating the gain.

Here is the schematic diagram of the circuit: The first and second.

Unlike vibrato effect that produce frequency modulated, this tremolo effect will produce the same effect as quickly turning up-ad-down your volume control repeatedly.

Here is the schematic diagram of the circuit: Q1 is general small signal audio transistor, you can use almost any type of NPN small signal transistors.

Basically, its a pair of filters whose output is combined through the 100k mix pot.

The 39k.01 filter attenuates the highs and only passes low frequency.

This filter passes the high frequency and filters out the lows.

The C1 cap bypasses R2 when the wiper is adjusted so that it is at the top end of the pot and it creates a treble boost.

This circuit has some advantages such as it will work under tough conditions, very simple and has high input impedance.

This circuit will not load down electric guitars because of the high input impedance.

Here is the circuit:A 9-volt battery is typically used as power.

Guitar Compressor Circuit Schematic