Foot switch connector

Foot swithc connector: Front view
Foot swithc connector: Front view

As a Shakuhachi player I need my hands on the flute. So I use me feet to manipulate parameters and switches on the synthesizer. This module was originally build for my Shakuhachi to Synth project to provide the possibility to connect foot switches with the synthesizer and keep the patch intact when they are removed. The signal is not routed through the foot switch. Instead CMOS switches are used, turned on and off with the foot switch. So the signal stays within the synthesizer and the connection to the foot switch carries only DC. Removing the foot switch does not interrupt the signal flow in the synthesizer.

Specs and features

  • Four independent switches
  • Signal flow stays intact when foot switch removed
  • Runs on +/-15V and +/-12V
  • Power consumption below 10mA each rail

The documentation and the Gerber files for download can be found in my website.

Foot switch connector;: Schematic
Foot switch connector;: Schematic

The switch in the DG202 is hold in on position with a 100k resistor against the positive rail. With a foot switch attached you can pull down the hold voltage when you close the foot switch.

Foot switch connector: side view
Foot switch connector: side view
Foot switch connector: Back view
Foot switch connector: Back view

Quad output module

Quad output module
Quad output module front

This is my first step into the quad world. I want to build a system capable to deal with 4 channels. The tone control is derived from “Small Signal Audio Design” by Douglas Self second edition chapter 15. The maximum output volume is adjustable to protect your PA. You can connect the output directly to active monitors.

Specs and features

  • Bass, middle, treble tone control
  • Adjustable maximum output volume
  • Direct connection to active monitors
  • Runs on +/-12V and +/-15V
  • Power consumption around 85mA each rail

The documentation and the Gerber files for download can be found in my website.

Quad output module schematic control board
Quad output module schematic control board
Quad output module backside view
Quad output module schematic main board

A detailed description can be found in “Small Signal Audio Design” by Douglas Self second edition chapter 15.

Quad output module backside view

Headphone output

Headphone amplifier/output front view
Headphone amplifier/output front view

Not that much to say here. Simply a Headphone amplifier. Based on Douglas Self “Small Signal Audio Design” second edition pg.560 and pg.33 fig.1.12

Specs and features

  • Drives headphones in the range from 50R to 600R
  • Runs on +/-15V and +/-12V
  • Power consumption around 25mA each rail

The documentation and the Gerber files for download can be found in my website.

Headphone amplifier schematic
Headphone amplifier schematic

Simple dual amplifier with opamp-array (multipath amplifier).

Headphone amplifier back view
Headphone amplifier back view

Audio send and receive

Audio send and receive: Front view
Audio send and receive: Front view

This module is thought for sending and receiving audio signals. I use it to add some external effects to my modular. Albeit simple, it is very useful. For connecting pedals and external CV sources I recommend my Pedal/CV Send and Receive module.

Specs and features

  • Attenuates the out signal to line level
  • Amplifies the input signal to modular level
  • Amplitude control for in and output
  • Runs on +/-15V and +/-12V without changes
  • Power consumption around 10mA each rail

The documentation and the Gerber files for download can be found in my website.

Audio send and receive: Side view
Audio send and receive: Schematic

The outgoing signal is attenuated 1:4 with IC1B. P1 sets the output signal level. The incoming signal is amplified 1:7 with IC1D. P2 sets the input signal level.

Audio send and receive: Side view
Audio send and receive: Side view
Audio send and receive: Side view

Send and Receive

Send and Receive front view
Send and Receive front view

As a wind player I need to keep my hands on the wind instrument. This module was first thought for connecting pedals to my modular for changing control voltages. But it is useful to include external signal changers like echo or delay or any other sound and CV source as well.

Specs and features

  • Connects a banana system to external sources.
  • Runs on +/-15V and +/-12V without changes

The documentation and the Gerber files for download can be found in my website.

Send and Receive schematic

I think you need no description here.

Send and Receive side view
Send and Receive back view

Connecting a Banana System with 3.5 Eurorack

Banana to 3.5 Eurorack front view
Banana to 3.5 Eurorack front view

This module is needed for easy connecting a banana system to a 3.5 eurorack system. It is a passive module. No signal changes are made.

Specs and features

  • Connects a banana system to 3.5 eurorack
  • Passive. No signal changes

The documentation and the Gerber files for download can be found in my website.

Banana to 3.5 Eurorack connection schematic
Banana to 3.5 Eurorack connection schematic

I think you need no description here.

Banana to 3.5 Eurorack connection populated PCB
Banana to 3.5 Eurorack connection populated PCB
Banana to 3.5 Eurorack connection side view
Banana to 3.5 Eurorack connection side view
Banana to 3.5 Eurorack connection back view
Banana to 3.5 Eurorack connection back view

Output Module

Output Module: Front view

Output Module: Front view

This is my replacement of the original Elektor Formant COM module. I discarded the original circuitry because of the TL085 used with his unusual pinout and the availability of dedicated audio operational amplifiers. I used a more effective filter implementation for tone control. The tone control is derived from “Small Signal Audio Design” by Douglas Self Chapter 15. A optional level indicator makes it easier to find the right volume level for best SNR. The maximum output volume is adjustable to protect your PA. You can connect the output directly to active monitors.

Specs and features
• Bass, middle, treble tone control
• Adjustable maximum output volume
• Optional volume indicator
• Direct connection to active monitors
• Runs on +/-15V and +/-12V (with minor resistor changes)

The documentation for download can be found in my website.

Output Module: Schematic front PCB

Output Module: Schematic front PCB

Output Module: Schematic back PCB

Output Module: Schematic back PCB

A description can be found in “Small Signal Audio Design” by Douglas Self Chapter 15

Output Module: Stuffed PCB back view

Output Module: Stuffed PCB back view

Output Module: Stuffed PCB side view

Output Module: Stuffed PCB side view

Output Module: Side view

Output Module: Side view

Microphone Preamplifier

Microphone Preamplifier

Microphone Preamplifier

I needed a microphone preamplifier for my Shakuhachi 2 Synth project. So i build one. The schematic follows the circuitry given in the data sheet of the SSM2019. Nothing fancy. A optional volume indicator is added. I didn’t bother with phantom power. I already have a external unit and didn’t want to go into the trouble designing something. It is on my list for future versions.

Specs and features
Simple microphone preamplifier
Optional volume indicator
Runs on +/-15V and +/-12V

The documentation for download can be found in my website.

Microphone Preamplifier schematic

Microphone Preamplifier schematic

The schematic follows the circuitry given in the data sheet of the SSM2019. Nothing fancy. A optional volume indicator is added.

Microphone Preamplifier populated PCB

Microphone Preamplifier populated PCB

Microphone Preamplifier back

Microphone Preamplifier back