Wednesday, 29 July 2015

NLC - Buchla Style - Low Pass Gate (LPG) Build notes.

These are the build notes for the NLC (NonLinearCircuits) version of one of the classic filters of all time: the Buchla 292.
The 292 configuration consisted of 4 filters with CV control & a 3 pole toggle switch for each filter.
The  toggle switch allowed you to alternate between 3 modes: LowPass, Combination & Gate.
Gate is Buchla's name for a VCA.

Buchla still produce this filter in two forms: The 292h & the 292e (which goes by the grand title of  "Quad Dynamics Manager").

The 292e is the centre module. Notice that the toggle switches have been replaced with buttons.
 It has also gained velocity control & preset storage but is mostly the same as the earlier 292.

Here are some pics of the virgin NonLinearCircuit PCB & panel:

Andrew's build notes are here:


Useful Links:
1. CGS - Ken Stone's LPG
2. Buchla Tech - Verbos's excellent blog - 292c Secrets with schematics
3. Synth.NL.Blog - 292 5U build notes
4. Modular Synthesis - Build notes for Thomas White's LPG clone.
5. Doepfer A-101-2 LPG filter
6. Natural Rhythm Music - Thomas White 

The LPF filter design is a variation of the Sallen Key. Ever since professors R.P. Sallen and E.L. Key described it in 1955, the Sallen-Key low-pass filter has become one of the most widely used filters in electronic systems.
It's another form of what is known as a voltage-controlled voltage-source (VCVS) filter used to
implement a 2-pole (12 dB/octave) response.

Most VCVS use unity-gain operational amplifiers where the output voltage is the same as the input voltage.... At first glance this seems useless but the advantage is that they don't take current from the input source.
The input & output sides are in effect isolated.

The controlling element for frequency (in LP mode) and amplitude (in VCA mode) is the vactrol.
Basically a LED & photoresistor packaged in a light tight box. I reckon this is a really neat way to get voltage control over a variable resistor.

Andrew suggests experimenting with different types of vactrols. He has been using Silonex with good results. The NLC PCB is designed for a dual vactrol. Some of my earlier Buchla builds (eg the 208) use dual vactrols like the VTL5C3/2, and I have a few spare. So I'll probably use these first. Dual vactrols are actually two photo-resistors and a LED in the one package ....which is perfect as they sit in where R1 & R2 go. I might later experiment by using two single vactrols or even make my own vactrols if I feel like the challenge. There are lots of ways to tinker with this beautiful circuit.

Install IC headers & the Euro power connector first.
Then resistors & caps.
These 2 resistors (marked with and asterix) can be altered to suit your taste.
The caps marked 472 & 221 are 4.7nF & 220pF respectively..
I think MCCs (monolithic ceramic caps) are fine, others might insist on polys.

The 33k can be varied up to 51K .... It sets the Cv level.
I left it at 33k.
The 10K sets the gain of the output signal.

The switch must be mounted as close as possible to the PCB & watch the orientation (it's up/down, not left/right).

Sounds quite good ..esp the LP filter.
I reckon varying the CV level resistor is a good idea. The frequency pot is very responsive at the upper levels (8-10) , but volume drops away quite quickly below this.
I experimented with audio(log) vs linear pots and think a log frequency pot sounds better. (just my humble opinion).
I'll probably change that resistor to 51k.

It's done for now.

Click here to return to the NLC Build Index:

Sunday, 26 July 2015

Scanimate Matrix Switch Panels

I am lucky today to have finally received two remnants of the venerable Scanimate machine.
It's part of a early analog computer that was used in animation.
From what I've read, there were only 8 made.

The Scanimate was invented by Lee Harrison III, founder of Computer Image, in Denver, Colorado in 1969. This system was used to help create the Scanimate Films, in combination with Jim Henson's puppeteering.

I understand that these cane from two that were housed at Image West in Hollywood

This is a big part of animation history.
Scanimates were used extensively on TV & film in the 70's & 80's. If you ever saw Sesame St, Willie Wonka & the Chocolate Factory, or The Electric Company, then you saw Scanimates in action.

I don't have the whole machine. Apparently this was destroyed and only some parts were saved from "a container" on it's way to China.

But what is left are two gems.

Each case has a 8 panel patch matrix with 19 potentiometers.
The patch matrix is the same type used by ARP for the 2500 synthesizer.
Which is the original reason I bought this.
The Cherry Sliders switches are extremely hard to find.

The "Commutator" & "Axis" refer to this section of the Scanimate.
Final position, Initial position & size - refer to fig 6, above

"The Animation Aid Panel from the Scanimate. It appears to connect to the cherry switches. Notice the Patch Panel 122, a potentiometer section 123 and an oscillator control section 124.

The oscillator control section 124 includes two high frequency oscillators, numbers one and two, and three low frequency oscillators, numbers three through five. The two high frequency oscillators, approximately 90 KHz, are provided for raster bending. High frequency oscillator number one has a frequency adjustment potentiometer 125 and an amplitude adjustment potentiometer 126 for defining those parameters of the wave form. This oscillator can be phase locked." (US Patient doc)

1. Wickipedia
2.  Dave Seg's excellent Scanimate site
3.  Scanimate - Facebook Page
4.  Create Digital Motion
5.  AudioVisalizers
6.  Nick Campbell
8. US Patient documents.

Saturday, 25 July 2015

Where to find components for your projects - Shopping Carts

One of the most tedious tasks when module building is sourcing components.
Months later you've forgotten where you bought that SMD resistor, or the 9mm PCB mounted pot.
So to keep frustration levels as low as possible, here is a list of where to begin the search.

I'll try to keep this page updated with manufacturer links.
Please contact me if you have some better sources.
Cheers, happy hunting,


SMD (Mouser)
SMD chip (Tayda)
Through Hole (Mouser)
1/4W carbon through hole (Tayda)
General fixed value -- SMD & Through hole (Element14)

Ceramic Disc (Mouser)
Ceramic Disc (Tayda)
Film (Mouser) 
Polyester Mylar Film (Tayda)
Tantalum  (Mouser) 
Electrolytic (Mouser)
Electrolytic (Tayda)
Multilayer Ceramic Capacitors MLCC - SMD/SMT (Mouser)
SMD ceramic chip (Tayda)
General Caps (Element14)

Capacitor Conversion Chart

General (Mouser)
General (Tayda)
Sliders (great for your ARP 2600, etc)- (Mouser)
Trimmers - SMD - (Mouser)
Trimmer - Through Hole  (Mouser)
Linear Through Hole (Tayda)
Log Through Hole (Tayda)
General Pots (Element14)
General pots (Mammoth)

Op-Amps (Mouser)
Op-Amps (Tayda)
IC (general)  (Mouser)
IC - CMOS 4000 Series (Tadya)
Diodes, Rectifiers, etc (Mouser)
Diodes - Standard (Tayda)
Diodes - Zener (Tayda)
Transistors (Mouser)
Tramsistors - General (Tayda)
Tramsistors - 2N series (Tayda)
Tramsistors - BC series (Tayda)
LEDs - Standard - Through hole. (Mouser)
LEDs (Tayda)

Lamps (incandesent lamps)
General - (Element14)

Phone connectors / Jacks
General  (Mouser)  
Buchla Tiny Jacks (Mouser)
3.5mm plugs & jacks (Tayda)
6.35mm - 1/4" plugs & jacks (Tayda)
Banana Jacks for your Serge & Buchla - Cinch & Pomona (Mouser)

Power connectors:  Buchla EDAC 587-306-50-010 (Mouser)  
Power Supplies: Linear (Mouser) 
DC power sockets & jacks (Tayda)
DC/DC converters (isolated) (Mouser)

Toggle (Mouser)
Toggle (Tayda)
Slide (Mouser)
Slide  (Tayda)
Rotary (Mouser)  
Push Button (Mouser)  
DIP (Mouser)
*** SPST, SPDT, DPDT switches demistified *****

General (Tayda)
General - Fixed. (Mouser)

Knobs - General (Tayda)

General Pin (Tayda)
General (Mouser)

General links 

These companies should have most of what you'll ever need. 
And there is always Ebay. 

Element14 (free postage over $45 AUD)

+List of integrated circuit dimensions
+Surface Mount Nomenclature & Packaging.
+SOT (Small Outline Transistor dimensions)
+Voltage divider, LED resistor calculator 

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 -
Click here to return to the NLC (NonLinearCircuit) Build Index:

Karnak Temple - Luxor - Egypt

This is the second largest ancient religious site in the world, after the Angkor Wat Temple of Cambodia.

It's a vast site full of decayed temples, chapels, pylons, and other buildings.
Most of the extant buildings date from the New Kingdom.

These are pillars of the Great Hypostyle Hall from the Precinct of Amun-Re.

Function Generator - LZX Industries build pics & notes

 These are my build notes for  the Function Generator of LZX Industries. It's a nice easy build. The kit is only $99 (including components).

The FG  is a non-linear amplifier that produces an output which is an arbitrary function of the input signal.
It's great for solarization & waveshaping.

The input signal is split into three regions - Light, Mids, and Dark. These outputs can be amplified or inverted. This module was adapted from one built in the 1970's by Dan Sandin at the University of Illinois at Chicago

His Sandin Image Processor is a classic.
ETC (The Experimental Television Center) has a wealth of info about this synthesizer.

Muffs also has lots on this module.
And LZX's build notes and schematics are here:

The virgin PCB & faceplate.

 Resistors, diodes & ferrite beads first.

 IC headers, & caps next.
*** Ammendment : I may need to remove these IC scokets. Video circuits apparently are very sensitive to stray capacitance... this may occur in the ICsockets****

 These pots go in next:

Next mount the switch & jacks:
Install the power header:

Wire it all up & you're done :-)
I'm slowly building up a Modular Video Synth.
This comprises mainly LZX & Brown Shoes Only Modules.
Dave Jones is another manufacturer who deserves to be mentioned.
I've been waiting for his new Video Synth to appear for ages.

There is also the option to use modules not designed for video.
Here is a useful link:

Audio Oscillators with the LZX Visionary
(WMD Gamma Wave Source, Wiard Oscillator, MakeNoise QMMG, and the Toppobrillo TWF) 
Roland V-Synth XT as a Video Oscillator (waveforms)
What the Malekko Wiard Anti-Oscillator looks like and what the LZX VWG sounds like
Moddemix VS. LZX
Cwejman SPH-2 demo as a video module
LZX + Doepfer A137-2 Wave Multiplier
A-136 Solarization Tests
Colors of Shadows
WMD - Synchrodyne - LZX VIDEO

("Lovely filter that makes video look awesome. Syncs to verticals and horizontal.")

Livewire AFG ??
anti oscillator
Doepfer A-111 - VCO 
Doepfer A-110 VCO - I'm using this . Works well.
Doepfer A137-2, A196, A126 ???
Doepfer A- 170 - slew limiter.
PEG - pingable EG
Intellijel Planar
Malekko Envelator and Maths - yes !!!
Malekko Borg ("pretty for smearing out video") 
Cwejman S1
Harvestman oscillators - Piston Honda,- Hertz D 
Intellijel Dr Octature II 4 Pole Low Pass Filter & Octature Sine Wave VCO
Dr Octature 1
A envelope follower and quadrature lfo ??
Doepfer A143-9 Quadrature VCLFO 
Doepfer A-151 V2 Quad sequential switch
Doepfer Sample and Hold  
4ms Rotate Clock Divider
Morphing Terrarium

Intellejel planar  
Intellejel Spock ("cool stuff to video via its logic magic")  

A replacement for the LZX Audio Frequency Decoder might be a attenuator 
like the Doepfer A-183-3 to reduce modular level voltages to LZX levels (0-1Vpp).
Normal line levels (like out of a DJ mixer) might work un-attenuated. They are around 1.4Vpp
Some sort of BP filter that splits the frequencies would prob be a good addition
Syncing the visual cortex.
 "I would add since having the VSG as the main SYNC out that I just use the RCA out's of the Color Video Encoder as my Genlock signal for both of my external TBC's. The Color Video Encoder is connected with the same custom cable from the VSG and then to the VC. It works great as the main Genlock source.

 BTW if anyone is curious as to the cable configuration all you need is the first pair from the 14 pin connector(marked in red), those are the ground signal, and the last pair as that seems to be the sync signal. Take those wires and solder them to a male rca plug and then plug it into the 'sync in' of the VC and then switch the dip switch to slave." (DSC).

1. Frame Generators Vs TBC
2. MFB VD-01 to LZX
3. Audio Frequency Decoder
4. syncing the Visual Cortex