JonDent - Exploring Electronic Music: Buchla Format

Showing posts with label Buchla Format. Show all posts

Wednesday, 10 September 2025

TSNM buchla format - build notes - part 2

This PCB dates from 2017 ..It's a Mark 1

There are modern ones using Teensy 4.0 ..... Mk II

which you can still buy.

This is part two on my build notes.

Part 1 is here:

https://djjondent.blogspot.com/2025/06/doboz-touch-sensing-note-memory-buchla.html

Links

+ Official site

+ BOM

+ official build notes

+ users guide:

https://drive.google.com/file/d/1aTLM4nmC7pMoK5vsYQfeug6oFMj46Xcw/view

DIY resources

https://drive.google.com/drive/folders/1SNYV-ANfFsxx2BVhXfpxuKqykUcP-Gyv

This Mk I uses the old Teensy 3.2.

....

Teensy® 3.2

Teensy Loader Application - available for Windows, Linux and Macintosh systems

C22, C23 and IC 6 are not needed if your PSU has +5V

C16 & C21 - are these part of the +5v section of the PCB?

I've soldered c16 in anyway.

C6 --- DNP ??? do not place?

1N5819HW 2 D1, D2 DO-41 schottky rectifiers 511-1N5819

L1 = ??

L2 = ferric bead.

These are connected in parallel ... across either side of the PCB.

Thus I used one ferric beath .. the through hole one. (L1)

Caps : 47uF x 2

-------------

C17 - 100n (SMD ceramic)?? I think this is not right.

looks like an electro maybe 33uF ??

Is it C21 in the BOM??

-----------------------------------

MPR121 board & headers

It's a Adafruit 12-Key Capacitive Touch Sensor Breakout. This connects to the touch plates of the front panel

Cut the trace on the bottom of Teensy next to VIN pin to separate VIN from VUSB. This prevents

powering the Teensy simultaneously from USB and the eurorack power supply.

Teensy 3.2

The two pots - 10K B ... linear (B103)

Encoder

position the two displays and LEDs

The lower header is tricky.

I had to do some gentle bending of the ends.

you need to keep enough room for the two matrix displays... the legs aren't long

Bend these headers so you can solder them directly to the front panel

This is a side on view

to be continued.....

Wednesday, 9 July 2025

Verbos 254v (buchla format)

This is essentially two Buchla 257 modules in one.....

with an additional CV in.

Great for smaller systems where in one panel space

it can do most of the scaling ,

adding and modifying of voltages you would ever need.

Each section has 4 inputs.

Input 1/2: Inverts/attenuates and scales voltages

from the input .... allows for -12 to zero

to +12V control of whatever is plugged

into the jack

Input 3/4 : The voltages can be crossfaded with

the knob or a CV at the banana input

between.

V(Offset): Adds a DC offset to the final output.

The offset knob's range of output is

-12 to +12V

(12'oclock is 0V if nothing is plugged

into any inputs)

Wednesday, 18 June 2025

Buchla 257

The Buchla 257 is a really useful module.

The front panel is a bit intimidating, but once you decipher the symbols and letters its not too hard to understand.

[Va * K ] + {[Vb*[1-M]] + [Vc*M]} + Voffset = Vout

A great module for mixing, scaling, and processing Control Voltages. (the 257T can also be used with audio voltages)

There are 3 inputs: Va, Vb, Vc.

There are 3 knobs: K, M, Voffset

You can add, subtract, scale, invert & multiply voltages.

The above equation can be simplified to:

K + M + V = output

Va * K (Attenuverter): Inverts/attenuates and scales the voltage from input Va.... allows for -10 to zero to +10V control of whatever is plugged into Va

{[Vb*[1-M]] + [Vc*M]}: blends inputs "Vb" and "Vc" .

The voltages Vb & Vc can be crossfaded with the M knob

or a CV at the banana input between Va & Vc

There is a switch that when turned on, will apply +0.5-1V (depending on your calibration) directly to the Vb input

V(Offset): Adds a DC offset to the final output.

The V knob when increased will output 0-10V.

(with NOTHING plugged into the module, if you turn the V knob to 50% ,you

would have +5V show up at the output).

How I like to imagine this module is as a way to sum 3 voltages in creative ways.

Remember that you have two voltage processors. You can combine these.

For comparison see the Buchla 254v, Buchla 256 & 156.

254v (buchla format)

Monday, 9 June 2025

DOBOZ - Touch Sensing Note Memory - Buchla format 4U --- part 1

These are my build notes for the DOBOZ TSNM module

I like the compact format.

Its a sequencer +

Here are some pics of the raw PCBs

There are two versions of this module .

One uses a teensy 3.2, and a second uses a teensy 4.0

i bought this board many years ago when teensy's 3.2 were plentiful.

I recently received a NOS 3.2, so thought I'd finish this build.

My board is from 2017. rev 1.0

MPR121 breakout board.

Links

+ Official site

+ BOM

+ official build notes

SEMICONDUCTORS first

Orientation of IC1-IC5 and IC7, Q1, D1 and D2 is clearly designated on the PCB.

74HC595 2 IC3, IC4 - shift registers

mouser 595-SN74HC595DR

OPA171

IC5

SOIC-8 operational amplifier

mouser 595-OPA171AIDR

TL072

IC1

SOIC-8 dual operational amplifier

mouser 595-TL072CDR

ADP150-3.3V

IC7 TSOT-5 linear voltage regulator

Mouser 584-ADP150AUJZ-3.3R7

"The trickiest part may be the DAC8560 (IC2), it’s a VSSOP-8 device.

This is hand soldered

Use lots of flux , a fine soldering tip and fine solder.

... and a steady hand

--------------

MMBT3904

Q1 SOT-23 NPN bipolar transistor

Mouser ;512-MMBT3904

I didn't have this exact transistor.

I used this instead:

Encoder: ordered and arrived.

Mouser No:

858-EN11-HSM1BF20

Mfr. No:

EN11-HSM1BF20

Mfr.:

TT Electronics

Resistors..

Some of the resistors need to have 0.1% tolerance

2 x 100K, (R1 & R15)

1K x 1,

27k,

33k,

teensy 3.2

mouser

coco.

Sunday, 20 June 2021

NLC - BBx 291 VCF - build notes

Finally starting this build of the Nonlinear Circuits 291 filter.

This is inspired by the Buchla 291 bandwidth/bandpass filter.

The BBX291 in Eurorack format.

I don't own an original 291. They are extremely rare.

However I have built a few "clones" ... whatever they call them these days.

+ 291r - build pics

Don B didn't do many filters. I think he preferred waveshaping over filtering.

This however is a great sounding module, and well worth having in your arsenal.

The original 291 (and the clones) used vactrols - four for each filter. They were VTL2C3 vactrols which have a 10M1k range.

Andrew's version uses his "black box" idea.

Rather than use individual vactrols, the LEDs & LDRs are housed in a light-tight enclosure built into the PCBs. It's a really neat idea.

This is a pic of a LPG module that uses the same idea.

Andrew used some clear lens red LEDs and GL5516 LDRs (0.5M-5k) for this filter module.

I'll see what i have.

His suggestions are that if you are using any LDR with an off resistance less then 5MΩ you can leave off the two 10MΩ resistors as they will be superfluous.

Ones that get down to 1k or less are prob best

You can read a bit about vactrols here
https://djjondent.blogspot.com/2017/12/vactrols-optocoupliers.html

Here are some pics of the non populated PCBs and front panel.

On the panel the two CV pots are sort of attenuverters, so 0 is at mid-point.