Adding Vintage Hiss, Crackle, and Pop!

Posted by & filed under Noise, Projects, Synth DIY.

In general, we’re trying to keep noise out of our circuits. Somewhat inspired by this thread on DIYStompboxes, I thought it might be fun to build a circuit that could generate that “vintage background noise” sound so that I could make things sound like they’re being played back off a phonograph cylinder or an ancient 78rpm record or something. It’s been an interesting little challenge and made me look at some different circuit elements and try a few different things. First,… Read more »

Flangelicious – A super-dooper flanger (Now in 2 versions!)

Posted by & filed under BBDs+Delays, Flanger, Projects, Stompbox stuff.

Flangers are generally regarded as one of the most complicated pedals to build. A typical design has tons of chips and lots of circuit elements. Flangelicious isn’t like that. By using a microprocessor to generate an LFO-modulated clock signal directly, we can get rid of a lot of the non-signal path stuff and add features whilst we’re about it. This gives us a much cleaner, simpler design for a flanger with a genuine fully-analog signal path. In fact, it can all be done with… Read more »

DIY 4 Second Digital Delay

Posted by & filed under BBDs+Delays, Projects, Stompbox stuff.

Recently I’ve been working on a four second digital delay with tap tempo and delay trails. There are lots of digital delay projects already, but the vast majority of them are based on the PT2399, which limits both the length of the delay and the sound quality.   A quick summary of the features: 0 → 4 Seconds of digital delay 12 bit/32KHz input, 16 bit/32KHz output Delay trails (tails) on/off Clickless effect in/out bypass switching Momentary/latching feature on bypass… Read more »

Noise Reduction with Companders

Posted by & filed under BBDs+Delays, Chorus, Flanger, Projects, Stompbox stuff.

What’s a “compander”? It’s a simple way to make your circuit quieter! So how does it work? Let’s say we’ve got a fairly noisy effect, like a BBD. The basic idea is that you make quiet signals louder before you put them through the effect, and then you make them quiet again after the effect, and thereby make the noise quieter too. And that’s the clever bit! “Compander” is a compound of “Compressor” and “Expander”, since those are the two… Read more »

MIDI clock to analog gate pulses

Posted by & filed under Projects, Synth DIY.

How do you synchronise your modular synth with MIDI equipment? MIDI provides the MIDI clock message, but you need something to convert this to a format an analog modular synth can understand. Most MIDI-to-CV convertors will do the job, but that can be expensive. Here’s a cheap way to do it. The Druid MIDICLK chip converts MIDI clock signals into 0-5V analog pulses. It provides two separate analog clock outputs, which can be set at various division ratios of the… Read more »

Single VCA crossfader

Posted by & filed under Projects, Synth DIY, VCAs + Amplifiers.

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 is with a dual-gang pot. Each gang controls one signal, and it’s easy to wire so that as one increases in level, the other decreases,… Read more »

Voltage Controlled Looping Envelope Generator

Posted by & filed under Envelope Generators, Projects, Synth DIY.

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 of envelope depth and overall time. Gated looping mode loops while the Gate is high. When the Gate goes low, the envelope goes to the… Read more »

Voltage-controlled digital oscillator VCDO1

Posted by & filed under Projects, Synth DIY.

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 voltages very simple, even without an exponential convertor. Scanning through the wavetable with the Waveform knob. Sub Osc is a simple sine 2 octs down:… Read more »

Tap Tempo LFO (TAPLFO V2D)

Posted by & filed under Projects, Synth DIY.

This simple Tap Tempo LFO is based on the PIC 16F684. You can set the LFO frequency by tapping a tempo on a button connected to the chip, or by changing the Tempo CV. With this chip you can build tap tempo effects units or stompboxes, tap tempo controlled drum machines or tap tempo sequencer clocks. All of these are described in the datasheet below. The LFO can produce 8 waveforms, including a random (sample & hold) wave. All the… Read more »

Moog 911 ADSR Envelope Generator clone

Posted by & filed under Envelope Generators, Projects, Synth DIY.

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 would, since the control mapping is stored in a table in the code. JP worked out the required table values and a front panel design…. Read more »