@noyzelab's CELLDYNA Featuring Comdyna Analog Hybrid Computer & Cellular Automata Sequencer

via noyzelab where you'll find additional info & pics.

Update: All the sounds you hear except for the drum sounds in the end come from the comdyna - all analogue computer sound synthesis.

"For CELLDYNA I used minimal analogue computing elements (2 to 4 integrators, 2 potentiometers and an inverter) hybridized with a digital Cellular Automata sequencer driving various different synths. The spoken word samples are from a 1969 lecture from EAI titled 'Understanding the Analogue / Hybrid Computer'. In order to use such a small amount of computing elements I setup a fairly messy chaotic style feedback patch. I did this intuitively pluging around to see what happens on the scope while listening to the output in realtime. This approach worked well for this track, and enabled me to get quick results without resorting to theory. I made a bunch of recordings during Dec 2008 & Jan 2009, which I then edited into the final track."

Note this piece is featured in Dave Noyze Automata 49 which also featured afx dsp box commissioned by Richard James of Aphex Twin.

See the Comdyna channel label below for a few more posts featuring the system.

COMDYNA LGP-20 Analog Computing System

via this auction
As always, the seller's description:
"This machine is a combination of two Comdyna GP-10 analog computers and a MicroHybrid I digital control and interface system. It is one of only 20 made for the US Navy for use in their control laboratory schools. It offers 20 Operational Amplifiers, multipliers, coefficient setting pots, etc etc. The MicroHybrid has comparators, two counters, and I/O facilities for controlling the two GP-10 machines. The Operator's and Maintenance Manual, as well as various descriptive brochures, are included. It is assumed you have a basic familiarity with analog computation techniques, and the proper math backround to be able to set up the programming.

I purchased this machine some years ago for use in experimental music synthesis and composing. It was to be an expansion of my Comdyna GP-6 machine (which I am using currently). It was purchased in the condition shown and described below. My music research has branched out into other channels, so this Computer is not going to be used for the original purpose. Time to get it out of storage in into use!

This LGP-20 apparently had it's control panel broken at some point in it's life, and another LGP panel was provided. The replacement panel was cut out of a machine, and has a power transformer and the external sockets, as well as a connector for the regulator board attached. These parts are also on the main machine. The control panel harness must be spliced into the existing wiring. The main machine harness has bits and pieces of the switches, etc still attached. The clean-up and splicing job should take about an hour for a competent tech to perform.

The Power Supply regulator board is missing. There are three main options:
1. If one is still available from Comdyna, purchase it. Even a 'blank' board can then be easily populated.
2. Make a new board. All parts are common and are instantly available from Mouser, Digikey, etc,. The complete schematics and layout is in the Manual.
3. Operate the System using external power supplies - plus/minus 15VDC, plus/minus 10VDC (well regulated) and plus 5VDC for the MicroHybrid is required. Current is an amp or two, and there are many supplies which will do the job.

I have recently powered up the MicroHybrid portion of the System and it appears to be working as it should.

If you are experienced in basic electronic-technician level work, or can enlist the services of someone who is, restoring this machine will be easy. I just have too many other projects currently to allow the luxury of time needed for it." This one in via Brian Kehew.

Update via dkelvey in the comments: I have a LGP-20 that is working. I just this last weekend had it doing spyrogrphs at the Maker Fair in San Mateo, CA. I can assist in connecting the wires by giving someone a point to point listing. I'd be most interested in a copy of the LGP-20 manual though. That I don't have. See a quick flash of my machine and output at: http://www.youtube.com/watch?v=bDnIGM-J4Os [comes in at 1:30]
Dwight "

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Comdyna GP-6 Analog Computer

images via this auction

Not a synth, but definitely fun too look at.

"Comdyna GP-6 Analog Computer + Microhybrid I. Everything pictured is included. These are no longer made anymore. Complete info is available here: http://www.comdyna.com"

via the Comdyna site:
"The GP-6 carries on the general purpose analog computer as an old technology that stays forever young. Although the analog computer rarely computes in a manner that gave it its name, analog computing continues to thrive in the form of linear circuits. Analog computing fundamentals are the roots of linear circuits. The analog computer patch panel remains the only means of programming linear circuits, i.e. operational amplifiers into the endless number of analog circuit devices. With a GP-6 in the laboratory, stable, trouble- free signal conditioning, simulation, control, intrumentation, etc. circuits can be up an running in minutes.

Control laboratories are the primary installations. The GP-6 is the ideal starting point for teaching classic control system design. Working first with the GP-6, the student experiences not only the basic challenge of the control problem, but a hands-on development of the system physics into its math model, the patch panel programming of linear devices into interface and controller circuits, scaling analog variables and the use of simulation as a tool for both inductive and deductive analysis.

The GP-6 is also used in classroom demonstrations and advanced design projects where programmable simulations serve as linear and non-linear plants to be controlled. GP-6 simulations are high speed, continuous, and realistic stand-ins for testing analog and digital controllers and control systems.

Other than teaching, the GP-6 finds application as a handy, portable, general purpose instrument, the GP-6 patch panel a means to quickly program, as opposed to breadboarding, linear circuits.

Each GP-6 is a self-contained unit capable of simulating linear and non-linear systems of up to four state variables. Over 2000 GP-6 analog computers have been installed in over 400 university, government and commercial research laboratories.

USING THE COMDYNA GP-6 ANALOG COMPUTER, by Professor Ian Petersen, Department of Electrical Engineering, Australian Defense Force Academy, is an excellent presentation of programming and operating the GP-6.

The GP-6 Panel page offers a destailed description of the patch and operating panel functions."

For an analog computer with audio, see the Starkey Hearing Lab by clicking on the Starkey label below.

Comdyna LPG-20 Analog Computer

Title link takes you to shots pulled from this auction. Note this is not a modular synth but an analog computer.

via cebec.