Showing posts with label DIY. Show all posts
Showing posts with label DIY. Show all posts

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

Wiki

BOM




First components



---
" GL5516 LDRs you may need to adjust the caps to suit. GL5516’s on resistance is approx. 5k at 10 LUx, if your LDR is higher, use a lower value cap, say 4n7. If your LDR goes lower try a higher value cap, say 15nF-22nF" (andrew F)


--- I'm using eight 10uF caps
May need to experiment with these.
-------------------------------------------------------------------------------------------------------
"The 100R is part of the LED driver circuit; it should be considered the minimum value resistor to use. Feel free to experiment depending
upon your LED,"

I'll use a 100R.

 The Quad amplifiers





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

pART  2 is here
https://djjondent.blogspot.com/2020/03/nlc-shat-noir-build-part-2.html

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


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

Tuesday, 18 June 2019

Oscillator Cores & Exponential Converters

A bit about Oscillator Cores.... they are one of the building blocks of VCOs

VCOs have 3 main parts :
1.The core/cores
2.The waveshapers
3.The exponential converter

This page is mostly about the core (though I'll touch briefly on the other two).
When I first started out, I though that the waveforms in most analog modular VCOs were produced independently. This however is very far from the truth.


Most VCOs derive their multiple waveforms from just 1 main waveform known as the oscillator core.
The other waveforms such as sine and square are usually produced using waveshapers.
Whenever you buy a VCO, most manufacturers will describe their oscillator as having one core or another.

There are 2 main waveforms used: triangle and sawtooth.
They are produced differently and both have their strengths and weaknesses.

They  both use what are called integrating capacitors.

The simpliest waveform core is the sawtooth.... and thus seems to be more common.
It works on the principle that capacitors store charge. They fill up with charge until a reset voltage is reached. The rate at which the capacitor charges up is determined by the input voltage. (ie it's voltage controlled) ... this rate of charge/discharge is the frequency of the oscillator.

The triangle waveform is a bit more difficult to make as a core.
Instead of the charging/discharging of the capacitor, we have a change in direction of the current.

Both cores have a timing mechanism that resets the waveform back to its starting point by discharging the capacitor. (Then the cycle starts again).

The timing mechanism is usually a comparator. When the waveform exceeds a reference voltage the comparator triggers and the waveform resets.
The retrigger mechanism can be something like a transistor. If it is a digital timer then the oscillator is what is referred to as a digitally controlled oscillator... DCO,  instead of a VCO (Voltage controlled oscillator)

VCOs that have two cores are very rare. The most obvious is that of the ARP 2500

The 1004 has both triangle and sawtooth cores.
Both cores use a single reset mechanism.

The later ARP 2600 used 4027 & 4027-1 VCO submodules. These had a 10 Vpp sawtooth output.

The Buchla 158 Dual Sine-Sawtooth Generator  and the 144 Dual Square Wave Generator both use a sawtooth core. 
The later Buchla 258 was a triangle core dual oscillator. The 259 is also a triangle as far as I know.
The modern Buchla 261e breaks the mold ...it has a digital sine wave core. ( but the timbre section is analog).
The Roland SH-101, Oberheim Ob-Xa and Moog Memorymoog all use a Curtis CEM3340 chip.
This is a triangular core.
The Yamaha CS series VCOs use a sawtooth core oscillator.
The very early descrete component (no ICs) RA Minimoog VCOs (of which I understand only 300 exist)
used a sawtooth core.


-----------------
The exponential converter converts a linear control voltage into a exponential current.
Why is this needed at all ??? 
It's needed because most human senses (including hearing) are logarithmic

The exponential converter helps the oscillator core create a waveform that has a frequency logarithmically proportional to the input current. These converters are very very temperature sensitive.
This is a picture of the exponential converters of the 1004 VCO. It's part of an ARP 2500.
The 4001was an encapsulated NPN based current generator. 
The 4002 was PNP based.
The circuit boards were enclosed inside a plastic case which was filled with an epoxy potting compound.
This case helped stablise the VCO tracking of the 2500 but also made any future repairs very difficult.

The most basic type of exponential converter uses a bipolar junction transistor. (BJT).
and maybe some voltage dividers and a tempco.
The NPN type seems most popular. (though you can use a PNP).
For a single transistor, there is a  exponential relationship between the Vbe and Ic
(voltage between the base/emitter & collector current).
Here is the equation:
 
 This all looks pretty straightforward except for the problem of temperature.
The collector leakage current is influenced by temperature so in order to maintain accuracy we must keep the transistor at a constant temperature.

If your VCO uses a 1V/oct tuning, then any 1V increase, must double the VCO's frequency.

Of course not all synths use logarithmic voltage control.
Korg and Yamaha use linear voltage control (often called Hz/volt).
Here, the frequency is directly proportional to the input voltage and there is less of a need for exponential converters.

Links
+ A bit about Transistors
+ Waveshapers

Saturday, 15 June 2019

Wiard Joystick - Model GR-1209B

Some pics of the Frac format Wiard Joystick GR 1209B

 iT'S A very simple module.
The joystick features a two-axis CV output as well as a pushbutton that triggers a gate output. The joystick does not employ return springs, meaning it stays where you place it until you move it again.


Should be easy to build.
The green wire in the photo connects to GND. The red wire connects to +12V

The joysticks are easy to find on ebay,

For the record, Grant produced a few variations of this joystick over the years.
The old 300 series had the 311 with the analog voltmeter.


Then came the beautiful 311C
The two JAGs joined the 2 joysticks

In Frac this came out: The GR 1211




And there was also the joyrider which combined a borg filter with the joystick


The JAGs found their way into the eurorack format, but sadly not the joysticks
Still, there are plenty of other eurorack joystick makers
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
Wiard Index
,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

244r

Some pics of the 244r,
These aren't official build notes... more my personal pics to help trouble shoot my build.

There ARE two microcontrollers.
It doesn't look like there are any programming headers on the PCB so I may have to program these using
a breadboard.
 sOME PICS  of the naked PCBs.






VCAs
The V2164 is a quad VCA. You can also get these from thonk
http://coolaudio.com/docs/COOLAUDIO_V2164MD_DATASHEET.pdf






The 700-MAX5250BCPP is a
Digital to Analog Converters - DAC 10-Bit 4Ch Precision DAC


The 556-ATTINY84A-PU is a
Amtel 8-bit Microcontroller - MCU 20MHz Ind. Grade 
There are 14 pins.


The 556-ATTINY88-PU is a 
8-bit Microcontrollers - MCU 8KB In-system Flash 12MHz 1.8V-5.5V 
It is 28 pin DIP that can be plugged into a breadboard
 

Each have their own firmware
DOWNLOADS:
ATTINY88 FIRMWARE REV1.0
ATTINY84 FIRMWARE REV1.1 





How should i program these chips?
Could use a AVR programmer or arduino ??
I have an Olimex so might try that first
https://www.olimex.com/Products/AVR/Programmers/AVR-ISP-MK2/open-source-hardware 
The Olimex has a 6 pin & 10 pin ribbon cable

The 10-pin cable fits only the ICSP10 connector.
(In Circuit Serial Programmer)


 The Olimex AVR-ISP-MK2 doesn't provide 6-pin ICSP connector.
The 6-pin cable is for PDI and TPI connectors.
I'll be flashing the chip via the ICSP 10 connector. 
Pin 1 can be identified with an arrow and the red stripe 


So, Depending on the connectors available on your target board you might need an adapter called AVR-ICSP (these connectors are pretty common on mutable instrument boards, but this Buchla format module doesnt have any header ... So I'll need to program using a breadboard.

 This is the ATtiny84 being flashed.
Look for the green LED (instead of red). Green = OK.


And the ATtiny88

Recommended operating systems:- Windows 7 or Windows 8 or Windows 10- any frequently updated Linux distribution- any Mac OS/OSX 
Recommended software tools:- Atmel Studio 6 or Atmel Studio 7- AVRDUDE 6.0.1 or newer- Arduino IDE 

I decided to use Atmel studio 7.

Long installation... about 20 mins.
But programming seems very smooth.

 Tools ----> Device Programming ----->

Choose the tool (AVRISP MkII), then device (eg ATtiny88) .
Hit "apply".


Then go to "Memories"
 You pick the hex file to upload from the Flash (8Kb) section ... dropdown box.


 Hit the "program" button to upload the hex file.

 



Links
+ About Microcontrollers and synths
+ Modularsynthesis.com
+ TheElectricMusicStore
+ BOM

===============================================
Buchla index
==============================