Wednesday, 24 May 2017

1050 Mixer sequencer - Build notes

This is a Eurorack module inspired by the ARP 2500 mix sequencer.

There are lots of SMD components so it's probably not a good one for beginners.

Here are Andrew's build notes:
http://www.sdiy.org/pinky/data/mixseq1050BuildBOM%20vers1.pdf

Muffs notes:
https://www.muffwiggler.com/forum/viewtopic.php?t=154469

EMW from Brazil have also done a 1050 module
EMW Mix sequencer (Sonic state review)
http://www.sonicstate.com/news/2015/09/29/eurorack-sequencer-based-on-arp-2500-in-action/

Back to the NLC build:
Some pics of the virgin PCB & Panel

Some NLC words of wisdom

Some SMD soldering practice.
Get those ICs on first. These are 0805s
The sequencer section uses one CD 4017 (decade counter) , three CD4071s (quad 2-input OR gate) and  one CD 4081 (CMOS Quad 2-input AND gate).


The 4017 decade counter is central to this sequencer.
Sending a pulse to the clock input (pin 14) sends a pulse out from each of the outputs in sequence.

A bit about gates.

CD4071 (quad 2-input OR gate)
 
 Truth table of the OR gate:

 CD 4081 (CMOS Quad 2-input AND gate).
This is the truth table for the AND gate

Saturday, 1 April 2017

Buchla 200 - Friday night patch

Just having fun with the 200.
That 296 filter is wonderful.

#buchla296 #programmable #spectral #processor #modularsynth #vintage

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Micro Granny - Basl Instruments

Thanks Andrew for bringing this over

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Its a monophonic granular sampler. It reads wav samples from microSD card and applies granular algorithms to them. You can also adjust start, end, sample rate (tuned or free run), crush and envelope (attack release).

It's all 8-bit.
Uses a microcontroller / Arduino platform.

Korg PS 3200

The lovely Sounds of the Korg Ps 3200

Andrew brought his Future Retro Zillion sequencer yesterday
so we decided to test it out on the Korg.

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Wednesday, 29 March 2017

Buchla Preset card - DIY mixer for 208 easel

One of the best things about the Buchla Music Easel is its program card.
It's really not just for presets ... esp the original card invented by Don Buchla back in the 1970s.


I'm guessing he may have wanted us users to experiment with electronic circuits.
Why else would Don have placed a mini "breadboard" with +/- 15V rails on the program card?

The Buchla SILI-CON CELLO from 1978 is a good example of his use of breadboard circuits in a fully
functioning system. It's a shame the current BEMI program cards have removed this homage to the age of DIY electronics.

This is my latest use of the card: a DIY mixer.
(The 10U system doesn't have a dedicated mixer).

The circuit is very simple.
Just one dual op-amp (TL072)

It's a basic unity gain inverting configuration. In the first half the 4 inputs are mixed into the inverting input of a op-amp. Since the output signal from this op-amp is inverted, the 2nd op-amp  re-inverts it. 
Power goes to pins 4 & 8. The unmarked resistor on the right is 1K

Thanks to Ken Stone for the original circuit. and Justin from MetroModular for his advice.
Ken's schematics show the possibility for using this as a CV mixer & attenuverter.

Breadboarding the circuit. Just two inputs on the left without pots.
It works on +/-12V above and +/-15V below.

Might try building a mixer using the OPA2134.
It's pinout is the same as the TL072.