I typically use the 12-bit MCP4822 DAC to produce a CV for the SSM2164 (or CoolAudio V2164, it’s the same thing) . This is a good, cheap combination. However, the 4822 produces an output of 0-4.095V, whereas the 2164 needs 0-3.3V. It is possible to use a simple voltage divider to reduce the voltage to […]
Update, June 2026 – this article has been superceded by a new one! Click here to read it! While this article was the best I could do at the time, there’s stuff here that’s factually wrong and that I’ve corrected in the new article, so go and read that one instead! However, for the sake of […]
Years ago, I discovered that it was possible to analyze a waveform and discover what harmonic components it was composed of, and that the magical technique to do this was called “Fourier Analysis”. I tried to find out all I could, but all the references I could find were aimed at university level mathematicians, and […]
The PT2399 datasheet gives some data showing the relationship between the resistor on pin 6, the clock frequency, and the delay time. Unfortunately, it doesn’t offer any design equations relating these three variables. So, can we derive some? Yes, we can! They’re all included here. First, a quick summary of what I’ve learned, if you […]
There are a number of situations where it is useful to be able to crossfade between two different signals with a single control. Examples might be a wet/dry control on a delay effect, or a waveform knob on an oscillator that goes from ramp to square continuously. The simple and obvious way to do this […]
This project is a development of my earlier VCADSR envelope generator. Whilst that chip had both GATE and TRIGGER inputs, this chip replaces the TRIGGER input with a MODE CV that allows selection of normal ADSR, Gated looping, or full LFO-style Looping modes. Standard ADSR mode generates the shape you expect, and allows CV control […]
A single chip 1V/Oct voltage controlled digital oscillator, with 20 waveforms in a scannable wavetable. The VCDO uses a PIC 16F1847 microprocessor to create a versatile and simple voltage-controlled 8-bit digital wavetable oscillator. All oscillator parameters are controlled by 0-5V control voltages. The chip has a native exponential control response, making interfacing with 1V/Oct control […]
2018 Note: Obsolete! This chip has been superseded by the TAPLFO 3 The new chip adds several features, has additional waveforms and improved resolution, and also no longer requires a crystal. It’s an improvement in pretty much every way! Head over and check out the data sheet. This simple Tap Tempo LFO is based on the […]
A clone of a classic using my PIC code by J-P Desrochers Jean-Pierre Desrochers wanted to copy the response of the Moog 911 envelope generator using more modern technology. He asked me if it would be possible to tweak the response of my PIC envelope generator to do this, and I told him that it […]
A pure white audio noise generator using an 8 pin PIC 12F675 This pages describes a simple digital noise source that produces pure white noise over the whole audio band – out to more than 40Khz, in fact. With filtering, you can derive pink noise and other colours. The circuit diagram included below was developed […]
