Monday, 29 April 2019

Bi-di Choppers

This is a dual stripped version of the original Chopper. A very easy build with few components. It can be used as a 1 into 2 switch or 2 into 1. A CV signal can be used to help control the switching point, tho Choppers are different from regular switches as the signals being switched also control the switching.
It can be used to process CV and audio signals.
The basic idea for the Chopper is from a 1975 paper titled – ‘A nonlinear modulator using delta principles’ by S.K. Mullick and K.R Srivathsan, although this version drops the comparator output, makes the slew stage adjustable, converts the 2 inputs so they can also be outputs and adds an in/out stage before the slew section.

panel = USD20
assembled = USD160


This module is straight out of the Lunetta playbook. It is simply a CMOS 4018 with buffers on all of its inputs and outputs, along with a 4081 to enable further divisions.
The divide by is patch-programmable, simply patch whichever number you wish to divide by back into the input and feed it a clock. The other outputs will follow the 1/n at various phase differences depending upon what is going on.
You can get quite silly by feeding signals into the J1-J5 inputs (jam) and sending a high signal (anything over 1V) to the preset enable.

PCB set = USD22
8HP Panel = USD20
assembled = USD190

Build guide and panel template on the NLC wiki

Wednesday, 10 April 2019

I can't believe it's not a VCO

PCB set = USD20
panel = USD20
assembled = USD180

This module is based on ideas presented in Electronotes #132. It is a VCF with a 'filter exciter' section to allow a wide variety of acoustic, semi-acoustic and not-acoustic-at-all sounds. In a sense it takes the concept of pinging the LPG or ringing a VCF one step (or 2) further. The decaying sound is fed back into the input via a VCA. The VCA can be controlled by a gate or an envelope (or both).
Another interesting point is higher frequency sounds tend to be louder.....which is what happens naturally in the big room.

Build guide & panel template on the NLC wiki