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Doepfer’s A-151 has unused pins 'DIGITAL OUTPUTS'

The following link shows the schematic of the old version of the A-151.

http://www.doepfer.de/faq/a100_faq.htm#vc%20switches

The latest version uses the DG409 dual 4-channel analog multiplexer/demultiplexer instead of the CD4052 for covering the full voltage range (±12V) of the signals. However, there is not much difference of the structure of the circuit between the two versions. A half of the DG409 is used for switching the channels of connections between the O/I and the I/Os. The other half is used for turning on the LEDs.

The latest version of the A-151 has unused header pins 'DIGITAL OUTPUTS' on the board.

The following figure shows how these pins connect to the circuit.

#Schematic #Modular

VC Delay Module using PT2399

I built a Dual VC Delay Module in the 12HP Eurorack format for my modular synthesizer. It is based on the MFOS Voltage Controlled Echo Module by Ray Wilson. ( http://www.musicfromouterspace.com/analogsynth_new/ECHOFXXX/ECHOFXXX.php ) I omitted 2 VCAs from the original circuit, and changed resistors' values at the 'delay time' control mixer inputs (R6, R8) for allowing the digital noise sound.

I referred following site for adding a tempo indicator circuit for the PT2399: http://www.diystompboxes.com/smfforum/index.php?topic=102660.0

#Modular #Eurorack

LM3914 VC Gate Sequencer schematic

LM3914 VC Gate Sequencer

I will describe details later.

LM3914: http://en.wikipedia.org/wiki/LM3914

'Binary output'? See below:

http://ankgw.tumblr.com/post/93523666147/

#Synth #Modular #Schematic

Expander module for Doepfer A-110

Doepfer's A-110 has some tap points on the board for adding the functions that are soft sync and linear FM. (Visit Doepfer's website for more information. http://www.doepfer.de/a110_tec.htm ) I built an expander module for using those functions.

(8HP)

Connecting two tap points "AC/DC" allows the DC coupled input.

(The above schematic from Doepfer's website http://www.doepfer.de/a110_tec.htm )

I used male headers and heat shrink tubing for connecting.

#Modular #Eurorack #Scematic

Passive ring modulator on a Breadboard

Testing the DIY passive ring modulator for my modular synthesizer. I referred this site. http://www.cgs.synth.net/modules/cgsrr.html

#Synth #Modular

Gate Sequencer with Binary Output

I built a gate sequencer module (in the 6HP Eurorack format) that has typical functions as follows: 8 steps output, Reset function, Reverse direction sequence, etc.

And then I added one more function that is the "Binary Output". It behaves like a 3bit Binary Counter.

At first, I think the function should only be personal use for control for an analog switch module. However, I noticed that it can be used like a clock divider.

#Synth #Modular #Eurorack

Study For Sample & Hold Modules

This track is recorded with a modular synthesizer and a 4 track cassette recorder.

#Audio

An example of FM synthesis

This extreme sound was generated by the FM synthesis on a PC (with "Argeïphontes Lyre 2.0.4") .

#Audio

An Arabesque Sequence With 4 Low Frequency Oscillators

This track was recorded with a modular synthesizer. But I used only a small set (2VCOs & 4LFOs) .

#Audio

How do I design a mixer module?

A mixer module is not particularly noticeable. However, it is a necessary article in the modular system. Now I'm thinking of a plan for a mixer module in the 8HP Eurorack format.

I think Doepfer's A-138 is a typical mixer module in 8HP. It can not only mix signals, but also generate a DC offset.

http://www.doepfer.de/a138.htm

A circuit example for a CV mixer with a offset function and an inverted output is here.

http://www.doepfer.de/DIY/a100_diy.htm

Doepfer's modules has enough space between knobs or jacks for easily manual operation, probably because they are used by many customers. However, in the case of DIY, we can design a panel in a narrow spacing as far as we can operate it. This is an example for a panel design for CV mixer with an inverted output in 8HP.

The inverted output is an interesting function particularly for mix CV signals. However, the bipolar attenuation is also interesting. It can generate various complex CV signals by simple waves of simple LFO's.

Figure - Bipolar Attenuation explained (This is a part of the instructions of the module "Plan B Model 14". )

https://web.archive.org/web/20071019005456im_/http://www.ear-group.net/bipolar.jpg

A circuit example for the bipolar attenuation is here.

http://www.cgs.synth.net/modules/cgs33_matrix_mixer_euro.html

Finally, I post a plan of the Dual DC Mixer with the bipolar attenuate function and the offset function.

#synth #modular #eurorack

Visit Original Link

Buchla 291 BPF VC Resonance Audio Demo

0s- No audio input. Feeding CV to the "Resonance CV" input (by the square wave LFO) cause self oscillation. 53s - And change the value of the "Center Frequency" . 1m32s- Feeding CV by the triangle wave LFO cause self oscillation. 1m52s- Increase slowly the audio input (a fixed pitch saw wave).

#synth #modular

Buchla 291 Band Pass Filter with VC resonance

I built the Buchla 291 Band Pass Filter (adaptation by Scott Stites and Jeff Pontius) in the Eurorack format.

http://mypeoplepc.com/members/scottnoanh/slsdiy/id11.html

I had difficulty in adjusting some behavior of this filter, probably because I have run this on ±12V and I used different LDRs. By adding some resistors near control pots, I worked it out. (But I still have to adjust more easily to control.)

The schematic doesn't have the VC resonance, so I try to add a circuit for VC resonance.

This is the schematic.

Front panel. (12HP)

Audio demo.

http://ankgw.tumblr.com/post/90852811832/0s-no-audio-input-feeding-cv-to-the-resonance

#synth #modular #eurorack #schematic

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