Tuesday, 21 July 2015

NLC Neuron & Difference Rectifer - build notes

The NonLinearCircuits Neuron module is facinating and unlike any module I have come across
so far in modular synthesizers. It's not a chaos module but instead acts like a neuron which is the
core component of the brain, spinal cord & CNS.

The features that define a neuron are electrical excitability and the presence of synapses
that transmit signals to other cells. Of course the brain is made up of trillions of tiny neurons
and this module represents just one.

The NLC Neuron can be fed up to 3 inputs (eg LFO, sequencer or EG signals). It's output
can be fed to a filter or VCO  (to control pitch on the oscillator, or cutoff on a VCF) or
to more neurons for some really crazy fun.

Andrew has put up a few useful links:
1. The Neuron Panel (4U Serge format)
2. Difference Rectifier / Neuron build doc.10 Jan 2013
3. Two Neurons build doc. 8 Jan 2012
4. Difference Rectifier Data, schematics, video, etc 
5. WAMOD build notes

Muffs has a great thread too:

Schematic Source : NonLinearCircuits

Here are some pics of the virgin PCBs & face plate.
The panel is for the Eurorack version of this module. So is the PCB on the left. All pots and jacks are mounted onto this PCB. It uses two TL 072 Op Amps

The PCB on the right requites extra wiring to the jacks so is probably better suited for other formats like 4U.
It uses one TL 074 IC

I'll just be doing the Eurorack module for now, so the following pics are for Euro only.
Headers first:
Resistors, diodes next
Caps, then ICs:

Time for the 100k Linear pots (100B)

We now need ten 3.5mm jacks:
Line the up thus

Attach the faceplate & screw the jacks into place before soldering the jacks to the PCB.

After the jacks are soldered connect the grounds with scrap wire offcuts.

You're Done.

The Difference Rectifier:
There is a +ve & -ve output.

The output is the difference between the voltages of the two input signals, this difference is then split into iits positive and negative components. "what does it all mean? A one op amp, 8 resistor and 2 diodes circuit that churns out weirdness". The schematic and formula are here - http://www.sdiy.org/pinky/data/dif.html
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