Lockhart wavefolder (2HP) - choice of perspex or FR4 panel
A 2HP version of the Lockhart wavefolder as popularised by Ken Stone with his CGS-52 module. With a difference (or two)
With this module, it's possible to control the amount of current running through the positive and negative arms of the wavefolding section, which can lead to some interesting results irrespective of whether you're fettling VCO or control voltages. The 'main' output gives the folded waveform whilst the 'square' output will, under certain circumstances, give an arrhythmic pulse train which can be used either as a modulation source or a square-wave oscillator in its own right.
Keep in mind, though, that the depending on the biasing of the transistors you may not get anything out of the square output despite there being a folded waveform present on the 'other' output.
Works best with sine or triangle-based waveforms but there's nothing to stop you putting, well, anything into it - altering the level of the input signal can lead to some very interesting filter-like effects. If you really want to fatten up a sound, run it through a low-pass filter (or any filter) before feeding it into the wavefolder.
Works _really_ well on basslines if you use a resonant filter.
Finally, on a technical note, the input signal must be at least 1.4V p-p - this is due to the voltage drops created by the two transistors in the circuit; the practical upshot is that this module will not work with audio signals unless they're amplified (a lot!) whereas most VCOs and CV generators will workjust fine.
NOTE THAT THERE IS NOW A CHOICE OF PANEL MATERIAL
- if you're on a budget then the 'old style' engraved perspex panels are available, otherwise there's now the option of 1.6mm FR4, which is the same stuff that PCBs are made of; whilst narrower FR4 panels have a bit of flex, they're far less prone to breakage than perspex.
Mounting hardware and a power cable are also provided - FR4 panelled modules will have M3x6 machine screws, perspex panelled models will have M3x10.
100% hand-made with surface-mount components and, best of all, it fits inside 2HP. With a bit of knob-twiddling, you can make it sound like this: https://soundcloud.com/yorkmodular/lockhart-wavefolder-sample