Dual Comparator and Gate Delay (Issue 2)

This is an effective CV and audio processor that features two comparators and a gate delay circuit in a compact 1U panel design.

http://www.oakleysound.com/comp.htm

Dual Comparator

A comparator is a functional circuit block that allows two signals to be compared with one another. The output of the comparator is either high (+5V) or low (-5V) depending on which signal is more positive than the other.

Each comparator has two inputs, input A and input B. Input B is directly controlled by a reversible attenuator that affects the level of the signal fed to the comparator circuit block. A reversible attenuator can not only alter the level but also the polarity of the signal too. With the pot in the positive direction, the output of the comparator will be +5V if the input A is more positive than the attenuated input B. If input B is more positive than input A, then the output is -5V. A LED will light when the output is in the high state.

If no jack is inserted into the input B, then input A will be compared to a fixed voltage. This fixed voltage is controlled by the pot, and can be set to anything between -7V and +7V.

The output of the comparator can be treated as either an audio signal or as gate signal to control envelope generators and sync LFOs.

Dual Gate Delay

If no jack is inserted into one of the input A sockets, then you can use that channel as a gate delay circuit. Inputting a standard gate signal into the 'gate delay input' will cause the output of the comparator to go high after a certain length of time. That length of time is controlled either by the appropriate 'amount' pot directly, or by a voltage present at input B which can then be controlled by the 'amount' pot. The gate may be delayed by around 5mS to around 5 seconds.

Both comparator channels are fed from the same gate delay circuit, so you can simply set up two different delays from one gate. This can be used to create multiple triggers from a single 'note on' event.

Please note: in common with most gate delay circuits the delayed output will immediately drop low when the gate goes low. Thus the gate delay process affects only the start of the note, not the end.

Uses

This compact and versatile module can be used for a variety of purposes. These are some examples of its use in a small to medium size modular:

1. To create delayed gate signals for pseudo echo effects.
2. To create powerful multiple phase pulse width modulation from triangle or sawtooth VCO/LFO outputs.
3. To create a voltage controlled switch in conjunction with a VCA.
4. Creating hard distortion effects from an audio signal.
5. Creating random gate events in conjunction with the Oakley Noise/Filter module.

http://www.oakleysound.com/comp.htm