chopper tremolo effect

Posted on Feb 6, 2014

A Tremolo is an effect unit that modulates the amplitude of the guitar signal, usually in a triangular waveform. This version uses a square waveform, for a more switching, choppingkind of effect. This kind of effect can be heard in the beginning of Plant Telex by Radiohead. Tom Morello of Rage Against the Machine uses this kind of effect too, he, however, uses a kill switch  on his guitar, which he controls manually. T

chopper tremolo effect
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his is a very simple and low quality circuit, whose problems can be seen in the following video. I built it in about an hour, that`s how simple it is. It is based on a simple NAND oscillator from an LED Chaser circuit that I had built maybe a year ago. Here`s the circuit diagram(proudly drawn in GIMP): The idea behind the circuit is quite simple. The NAND provides a square wave pulse (and there are better places where you can understand how it works, google NAND oscillator ) that is then hooked up to the 4066 IC. The 4066 is contains 4 analog switches, where each switch is controlled by a single input pin as seen in the following diagram: I used 2 of the 4066 switches. The first one, connects the input signal + and the output signal +, while the second one connects the output signal + and the ground. One switch is controlled by the output of the oscillator, and the other is controlled by the same output, but inverted. The result is that the output signal switches between the input signal, and no signal (ground connected to +). the popping noise you describe is due to abrupt switching of the signal from some non null value to zero. To remove this, you need to add a zero-crossing circuit to trigger the switching. A number of digital potentiometers have a built-in zero-crossing detector. For example the max5457, which also has a mute input which you could use directly in your circuit.

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