CGS sub-oscillator/harmonic sequencer (view source)
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Running both inputs from the same LFO/clock signal, and feeding the mixed output into the 1V/octave input of a VCO gives you a pattern based sequencer, where the prescaler, ring modulated outputs, etc., all have a bearing on the pattern. Quite interesting patterns can be created this way. Each knob of course varies part of the overall structure, instead of a single note as per a regular step sequencer.
=== Notes ===▼
* When using the sub oscillator, try feeding an audio signal into the "a" input, and a low frequency signal into the "b" input, then mix the "a" channel and multiplied signals together. Due to the action of the EXOR gates, the output of the "a" channel can be gated partially to fully on and off, giving some interesting tonal sequences.▼
* Asymetrical input waveshapes will not drive the input multiplier properly. Nothing says you can't exploit this either.▼
== Construction ==
=== Notes ===
* Don't tie all the wires going to the pots together. This causes some [[crosstalk]]. Either keep the wires apart, or use shielded cable.▼
* The 22k resistor in the mixer section marked
=== Alternate layout ===▼
Having had the prototype in my synthesiser for some time now, a second layout became obvious. Instead of having pots for both the B channel and the multiplier outputs, I used a 4 pole 2 position switch to select between the B channel and the multiplier outputs, saving me a lot of panel space. The x2 output was sacrificed, and the rotary switch to select the prescale was replaced by an SPDT switch for the bypass function, and a SPDT center off switch was used to select between divide by 3, 7 and 5. 7 is hard wired as the default on the PCB, so no connection is needed to the switch.▼
*[[:File:cgs_suboscillator.gif|200 DPI B&W printable panel artwork version 1]]▼
*[[:File:cgs_suboscillator2.gif|200 DPI B&W printable panel artwork version 2]]▼
== A little on how it works ==
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| colspan="2" |* see wiring diagram.
|}
▲== Notes ==
▲* Don't tie all the wires going to the pots together. This causes some [[crosstalk]]. Either keep the wires apart, or use shielded cable.
▲* When using the sub oscillator, try feeding an audio signal into the "a" input, and a low frequency signal into the "b" input, then mix the "a" channel and multiplied signals together. Due to the action of the EXOR gates, the output of the "a" channel can be gated partially to fully on and off, giving some interesting tonal sequences.
▲* Asymetrical input waveshapes will not drive the input multiplier properly. Nothing says you can't exploit this either.
▲* The 22k resistor in the mixer section marked "*" sets the overall gain of the mixer. Omit it if wiring in a master level pot. (This resistor is shown as 47k on the current circuit diagram.) See [[CGS DC mixer|CGS04 DC mixer]] for more information as the mixer portion of this circuit is essentially the same.
▲== Alternate layout ==
▲Having had the prototype in my synthesiser for some time now, a second layout became obvious. Instead of having pots for both the B channel and the multiplier outputs, I used a 4 pole 2 position switch to select between the B channel and the multiplier outputs, saving me a lot of panel space. The x2 output was sacrificed, and the rotary switch to select the prescale was replaced by an SPDT switch for the bypass function, and a SPDT center off switch was used to select between divide by 3, 7 and 5. 7 is hard wired as the default on the PCB, so no connection is needed to the switch.
▲*[[:File:cgs_suboscillator.gif|200 DPI B&W printable panel artwork version 1]]
▲*[[:File:cgs_suboscillator2.gif|200 DPI B&W printable panel artwork version 2]]
== See also ==
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