## Saturday, 28 March 2020

### NLC store open

This blog will no longer be updated.
https://www.nonlinearcircuits.com/modules

Also blog will continue here
https://www.nonlinearcircuits.com/blog

## Wednesday, 5 February 2020

### 1U PiLLs

This is a raw 12HP 1U version of the Mobius PiLL. It uses two cross-coupled Phase locked loop (PLL) ICs that go in and out of chaotic zones at audio rates. If you like making electronic noise, this module is for you. Oh yeh, it has vactrols.
It is a pretty simple build  and capable of a wide variety of sounds. The demo below is my usual noisy effort but it can be tamed if you choose to feed it CVs from sequencers.

There are 5 inputs, everything affects everything:
FM IN - feeds both PLL ICs
CV Range 1 & 2 - these control the vactrols. The control circuits are very simple.....a resistor and a vactrol!
CV 1 & 2 - these inject a signal into the VCO control input, shove in anything from audio to CV rates and see what you get.

The 4 outputs are from the PLL VCOs and the phase comparators, all are pulse/square waves running from 0-approx 5V.

Matte black and white panels for Pulp Logic and Intellijel formats are available, please specify when ordering.

Please note the white Pulp Logic panel has the manufacturing code on the front, I paid extra for this not to happen but the manufacturer did it anyway and gave me my \$1.50 back. It would be a greater crime to chuck the panels because of this, so it is there, use some whiteout if you really hate it. In the same order I specified gloss black panels and got matte, also specified white PCBs and got one batch of white and one batch of green. Somebody was a bit unfocused that day.

PCB set and panel = USD12
assembled = USD60

## Thursday, 17 October 2019

### Dual LFO/VCO

This is an upgrade for the NLC thru-hole dual LFO and the thru-hole dual VCO.
The circuit is based on the thru-hole dual VCO but can be switched to operate in 3 ranges; 15Hz-10kHz, 1 minute per cycle to 25Hz (approx) and down to 20 minutes per cycle for the slowest.

Both have CV inputs with attenuating pots and sync inputs. The sync is quite hard and attempts to momentarily ground the timing capacitor, how successful this is depends on what else is going on. At slow LFO rates it works more like a wave-shaper.

The outputs are sine, stepped, square and triangle. The stepped outputs are S&H circuits sampling the sine-waves. They are clocked by the other oscillator, there is no external clock input :)

There is provision to install 1k tempco resistors if you want to try for 1V/oct tracking. Don't expect good tracking over more than 2 octaves tho, there are no matched transistors onboard. If such niceties are not so important, simply leave off the 1k tempcos and install regular 1k 0805 resistors on the bottom of the engine PCB.

PCB set = USD20
panel = USD20
Assembled = USD180

Build guide on wiki

## Saturday, 7 September 2019

### Mobius PiLL

This is a chaotic noise module, it is generally not very nice unless you are into noise. In which case, hello!!

There are several papers describing ways to couple PLL (phase locked loop) ICs to create chaos. I have been sitting on a stack of them for years but found the actual circuits quite limited in a synth.

Eventually it clicked that the low-pass filter needed to be a bit fancier than a pot and a capacitor, so this version gets two Buchla style low pass gate/filters.

The circuit contains two PLL chips and two low pass filters. The PLLs are voltage controlled together, the filters are controlled individually.

Normally in a PLL circuit, the output of the phase detector goes thru a low pass stage and then the output of this is used to control the VCO. In this version, the low pass filter outputs are fed to the non-inverting input of an op amp for it's own VCO and the inverting input of an op amp for the other VCO. Maybe the pic describes it best, this is from Intermittent Chaos in a Mutually Coupled PLL’s
System (Shirahama et al), tho I have seen similar circuits in other papers.

It doesn't need an input signal to lock to, it can run on its own, but it can be fun to give it a signal anyway. The other inputs are for Freq CV, LPG1 CV and LPG2 CV. Two of the outputs are from the LPGs and two are from the PLL VCO, these two are pulse/squarewaves, very nice for feeding into filters.

The PLLs and filters are all vactrol controlled but the PCB is a unpatented NLC black-box design, so no need to buy any expensive vactrols.

PCB set = USD23
Panel = USD22
assembled = USD200

## Tuesday, 20 August 2019

### Sloth DK

6HP Sloth DK

For those that have not seen the Sloth before - this module is a simple chaos circuit that puts out 3 slowly varying and never repeating CV signals. It is not random as the chaos occurs within a bounded region and generally moves in or between two strange attractors or wells.

It is really slow and can take from 8-20 hours to complete a chaotic orbit.
Generally the output signals range between +/-4V, tho mostly around +/-2V.
The middle output is simply a mix of the two main outs, passing through the pot to attenuate the signal if you wish (and it helps hold the PCB to the panel). It is a little hotter and more complex that the individual outs.

There are no inputs and no way to control it.

The large capacitors sticking through the panel never see more than +/-0.15V in normal use. Nevertheless you probably should not take the module out of the case and rest your tongue across their leads.

PCB = USD12
Panel = USD20
assembled = USD100

Build guide on wiki

flamingo situation.......

### 1U Signum

In the simplest sense, this is a switching module. It is a little different though because it has 3 states rather than just on/off:
${\displaystyle \operatorname {sgn} (x):={\begin{cases}-1&{\text{if }}x<0 amp="" if="" text="" x="">0.\end{cases}}}$

In this case, the module uses approx 1V, rather than 0V, as the switching point, so that it can be controlled by gates. It is simple to bring it back to 0V for those who think it should be.
Also the '0' state is really a result of the diode voltage drops rather than any circuit design trickery.

The signal on the bottom input is fed to the switch of the Switch jack (oh yes) so the incoming signal can switch itself without any help.
The three states actually mean there is a flat spot at the switching point, so the circuit can be used for audio but at slow rates there is a click, so it is far better suited for CV processing.

This circuit originally was used as the nonlinear element in the Primal Hyperchaos and two of them in the Hyperchaos Deluxe. I quite like it on its own, so the Signum Hyperchaos brought the signum section to the panel where it could be used as a stand-alone module. This version drops the chaos and just has the Signum.
The switching is done by diodes rather than a dedicated IC.

The panels are available in white/gold and black/gold in both Pulp Logic and Intellijel formats. Please specify which colour and which format you want when ordering.

Also the PCBs are the same for both panel formats and use a standard Eurorack power connector. There is no provision for the Pulp Logic 3 pin power connector.

PCB and panel set = USD10
Assembled = USD55

Build Guide on wiki

### VCAs

This 8HP module contains 3 VCAs and a fuzz/distortion. The VCAs are similar to the ones used in the NLC Cluster; simple OTA based but work very well.

The fuzz/distortion is part of the bottom VCA and is a typical diode based affair, on the PCB the space for these are thru-hole so you can install Si or Ge diodes or LEDs. Turn the Fuzz pot to 0 if you just want VCA.

PCB = USD18
Panel = USD20
assembled = USD160