Wednesday, 17 July 2019

FaderBank - 16n

Some of my build notes re the fader bank.
This is a eurorack compatible module, however it does use midi and i2c so I hope it is compatible with other synths.

The official website is here:
https://16n-faderbank.github.io/

You can make your own PCBs and panels for it.
Github
https://github.com/16n-faderbank/16n/tree/master/electronics

The module uses a teensy microcontroller

The official build notes are here:
https://github.com/16n-faderbank/16n/tree/master/build



cd 4067
This is a cmos 16 channel multiplexer


MCP6004
This is a quad op-amp

diodes: D1 to D4 are four SOD-123 diodes.

 R17 and R18 are 4.7k resistors.
+ If you plan on using I2C with an ER-301,
   Ansible or TXo, (ie I2C "MASTER" mode) you should populate the 4.7K resistors.
+ If you plan on using I2C with a monome Teletype,
   do not populate these resistors - it may well cause problems.

........................ I'll leave these off for the moment... see how it goes


 the stereo jack sockets for MIDI and I2C.


the 16 mono jacks. 





tHE Teensy 3.2


to be continued ... waiting for some parts

Tuesday, 16 July 2019

Shat-Noir Phaser - Build notes

These are some un-official build notes for the Non-linear Circuits Shat-noir Phaser
It's an eurorack module.

This module uses light dependent resistors (LDRs).
You can find other phasers using a similar idea: notably the Carlin, Compact Phasing A,
Morely Phaser and ADA final Phase.

You will need to build a light-proof box to house the LDRs and the central LED.


Links:
+ NLC Blog
+ BOM
+ Wiki




First components


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Click here to return to the NLC Build Index: http://djjondent.blogspot.com.au/2015/03/non-linear-circuits-ncl-index.html 



waiting for some parts .....To be continued................

bh

.................

Monday, 15 July 2019

The Apollo guidance computer & the NOR gate

If you are familar with modular synthesizers, you will probably be aware of logic gates.
But did you know of their connection to the Apollo mission to the moon?
It's nearly 50 years since those heady days.
Apollo changed our lives in so many ways & the technology used then, permeates our society to this day.

Above is a pic of the AGC - The Apollo guidance computer.
 (The original uploader was Grabert at German Wikipedia. [Public domain])
 
This was the computer that took those 3 men to the moon and back. In addition, it was one of the first computers to use integrated circuits (ICs). The AGC was in fact the world's first "embedded system".

Today ICs are everywhere. But back in the late 1960's they were a revolution 
NASA's goal was to use components that were low weight, had low volume & operated on low power. Coupled with this, they had to be extremely reliable.
With these goals in mind they decided to use a single simple integrated circuit for all logic functions.


Since just one chip was used, NASA could really test it under whatever extreme conditions it liked.... to make sure that it could survive everything which space travel could throw at it.
AGC dual 3-input NOR gate

  This single chip contained a three input NOR Gate. It's incredible to think that it's possible to carry out all logic functions to take men to the moon with just a NOR gate. 
  This gate gives a positive output only when both inputs are negative.


The beauty of the NOR gate, is that it is what is known as a universal gate.
In other words, it can be combined with itself to make any other  kind of logic gate

For example a NOT gate can be made by joining the inputs of the NOR gate.
 
The OR gate can be made by inverting the output of a NOR gate.

 The AND gate is made by inverting the inputs of a NOR gate.

 We can go on and on, but I think you get the idea.
The AGC dual 3-input NOR gate schematic

The above schematic shows the makeup of the NOR gates using discrete transistors.
They are just really simple NPN/resistor designs.
You could possibly build this using any NPN type transistor (for example 2N3904, BC547, BC548, BC549 etc.)
 The use of transistors for the construction of logic gates uses their ability to act as fast switches.

 NASA used about 5,600 NOR ICs in total for the later AGC versions. 

Getting back to synths, the 4001 IC is  a useful chip to have in your bag.
It's a CMOS IC containing four NOR gates

So in theory, you can build any logic module with just CD4001s

Below is a Serge module... one of my favorite Synth logic modules.
At first glance, there doesn't seem to be a NOR gate.
 AND: Output goes "high" when all inputs are "high".
 OR: Output goes "high" when at least one input is "high".
 XOR: Output goes "high" when a odd number of inputs is "high" and the rest is "low".

The logic inverters can change the functions into NAND, NOR and NEXOR.
 Note: a logic inverter turns a "0" into a "1" or a 1 into a zero
 It inverts the logic state, not the voltage value (i.e. +10V will not turn into -10V).

Links.
+ Schematics of the AGC
+ Ljunggren Audio
+ The Boolean Serge
+ CGS 39 - Ken Stone's Quad logic gate
+ Talking electronics - about the CD 4001
+ About CMOS
+ Pittsburghmodular logic banks
+ Transistors - basic info
+ Making logic gates from transistors

Sunday, 14 July 2019

Mahamudra 14

New Sound Waves are hosting a night of Modular Electronic Music this coming Wednesday.


Location: The Hideaway Bar.
                 156 Enmore Road, Enmore (Sydney)
Starts at 7.00 pm

Facebook link:
https://www.facebook.com/events/2349710731937070/

Performers:
7:15 Hunter 
7:45 Vitals 
8:20 ECHO.8OT
9:00 Virus Installer 
9:40 Allinaire 
10:15 Slit Sensilla 
10: 45 Post Global Disorder

rrt

...

Friday, 28 June 2019

Waveshapers

This is a bit of basic Synthesis... I'm writing this for a friend who is starting his journey.
All about wavefolders, wave multipliers, transfer functions etc etc.
You will see wave shapers in a lot of "west Coast" synths. Serge & Don Buchla used them extensively.

'''
The Serge TWS and WM are classic waveshaping modules.

Wave shaping is one of the fundamental parts of oscillator designs as well as being one way to achieve distortion and design new waveforms from existing waveforms. When building a oscillator core, often waveshapers are used to derive additional waveforms from a single saw or triangle core.
+ Oscillator cores & Exponential Converters

The timbre circuit from the Buchla 259 is another example of the early use of waveshapers.

I understand that Don's Harmonic Oscillator from the Buchla 100 series used waveshapers to add harmonics to the core oscillator. 
 There are lots of modern manufacturers of waveshaping modules in many formats.

Basically waveshapers map the input and the output of the waveform. They then apply a mathematical equation to that waveform (commonly known as the “shaping or transfer function”) that alters it's final shape.

If the original input signal is called x and the new output signal  is called y.
This function is called the transfer function.
y = f(x)

This is a really simple function but the basic idea is the same no matter how complicated things get.
 
The transfer function can be done either the old fashioned analog way with op-amps, diodes, etc or digitally where "look up tables" are implemented.

Don Buchla used both digital & analog waveshapers.
His Touche from 1978 had digital waveshaping. It had 16 digital oscillators that could be combined into eight voices.

Grant Richter used waveshapers in his Anti-osc & the Mega wave
The Malekko/Wiard Anti-osc is a triangle-core oscillator with voltage-controllable waveshaping.


The Megawave can be used as an audio wave shaper

To be continued ............