NLC Mobius Pill - Build notes -part 1

 These are my build notes for the Nonlinear Circuits Mobius Pill.

 

The MP is a chaos - noise module in Eurorack format.

So if you like chaotic noise this is for you.

 

The BOM looks pretty standard with no rare or hard to find parts.

You will need two 4046 ICs. 

These are your PLLs (Phase Locked Loops). 

(These PLLs create the chaos.)

There are also two Op-amps. These are standard 072s.

In addition to the two PLLs the circuit also has two vactrol based  low pass filters 

These filters are in the Buchla style... I think they are 292 inspired gate/filter combos.

The vactrols are all DIY (black box design) using LEDs and light dependent resistors.

The PLLs have a single combined voltage control input.

Each filter has it's own voltage control input.

 

 

Thanks  to Andrew for supplying this diagram.

It explains what's happening in this circuit.

There are two TL072 op-amps, two VCOs, two filters , and two PLLs

The phase detectors feed into the LPFs and theirs outputs are fed into the non-inverting inputs of one and the inverting input of the other.

The outptuts of each control VCOs.

There are 4 inputs & 4 outputs.

Inputs:

Input signal, Freq CV, LPG1 CV and LPG2 CV.

Outputs

Two of the outputs are from the LPGs and two are from the PLL VCO

Some pics of the virgin PCBs.

LEDs go here. These LEDs are part of the vactrols.

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The 4046 IC -- it contains a VCO, two phase comparators & a zener diode.

The zener diode acts as a voltage regulator, setting the voltage at 5.1V. across it, for voltage input into pin 4. This is the voltage that controls the number of oscillations for the output digital signal of the chip

  

The oscillator will produce a digital square waveform .

Analog input to the VCO is at pin 9.

Digital output of a square wave is at pin 4. 

This is fed into an op-amp and becomes the VCO 1 & 2 outputs.

 

PC (Phase comparator) 1 out (pin 2) becomes the LPG output.

Hopefully, this will help you trouble shoot, should you run into any probs.

The 4046s

First place the ICs,

 

 

Now the  nineteen 100k resistors.

Rest of the resistors... Caps next.

 

 

the

 The 1uF and 10uF need to be 25V or more.

To be continued ......Waiting for those diodes 

NLC Mobius Pill - Build notes -part 2

Links

+ NLC Blog

+ Build Guide on NLC wiki 

+ PLL - VCO basics- youtube
+ CMOS stuff

NLC Mobius Pill - Build notes -part 2

 

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