Circuits for Audio Devices, Synths, Effects & Modulations, Noisemakers & Amps
NAND-Gate Schmitt Trigger Oscillator
This is a fun little noise maker. 4 controls that interact to produce a huge range of output waveforms. I have had a lot of fun recreating vintage Sci Fi sound effects with this circuit, and it works brilliantly as a waveform generator to play with some subtractive synthesiser ideas. I like running it through a filter to emulate some D&B bass sounds.
If this circuit is sharing common power with other audio equipment, you may wish to add decoupling caps across the power rail, as close to the IC as possible. This will help stop signal bleed through on the power supply. I used a 100n and a 100p soldered directly to the power pins on the IC, as it was only after building it I discovered the issue.
VCF Voltage Controlled Filter
VCF Based on the Mastro Filter/Sample&Hold
This is the first audio module of a guitar controlled synth I plan on making into a bigger project.
My aim with this circuit, was to take the really nice sounding filter from the Mastro: Filter, Sample&Hold, but make something that could be controlled with a DAC output of a microcontroller. I can then make various plug in modules to control this filter, for example use a guitar to control the filter with the envelope, have a footpedal for manual manipulation, or make a step sequencer for on the beat control of the filter cutoff.
Note: this uses a bipolar power supply, this is documented on the Circuit Library: Utility page.
Reso control is a B1M Pot. CV2 has been tested with an input between 0 – 9v to control the bandpass filter cutoff. The 20k trimpot is 200k on my build, and that seems to work well. Its just forming a voltage divider so I don’t think the exact value is too important.
Version 2
This version has a blendable low pass & high pass, and should be far more versitile going forwards.
9 Way Stratocaster Wiring Scheme
Wiring scheme for an SSS Stratocaster with 2 push pull tone pots. Gives a total of 9 unique pickup selection options, including some Parallel and some Series options. I particularity like option (B)2 for psychedelic clean sounds.
| (A) Both Push-Pull Pots Down: | Normal Strat Wiring |
| (B) Tone 1 Push-Pull Up: | |
| 1 | Neck & Bridge (Parallel) |
| 2 | All Pickups (Parallel) |
| 3 | Middle |
| 4 | Middle & Bridge (Parallel) |
| 5 | Bridge |
| (C) Tone 2 Push-Pull Up: | |
| 1 | Neck |
| 2 | Middle & Neck (Parallel) |
| 3 | Middle |
| 4 | Neck & Bridge (Series) & Middle (Parallel) |
| 5 | Neck & Bridge (Series) |
