IR Input module, 50x200 mm, with three knobs, two switches, three jacks, three LEDs, and an infrared phototransistor

This is a modified version, in Kosmo format, of the Barton Musical Circuits 078 IR Input synth module. Barton describes the original version as follows:

This module is designed to allow infrared light sources to interact with your synthesizer. The most common household sources of infrared light are fire and remote controls. Infrared LEDs are also readily available to DIYers who wanted to experiment with creating new devices for controlling synthesizers through this module.

The infrared phototransistor that picks up the IR light may be AC or DC coupled to the circuit. Outputs are a CV proportional to the IR signal and a gate that turns on when the CV rises above a threshold set with a panel pot. Another panel pot sets the phototransistor sensitivity.

Modifications to Barton’s design include:

  • Added 3.5 mm TRS jack for a cable connecting to an external phototransistor and a switch to select internal or external PT. This allows using candles, lighters, etc. to control the synth while not having to have them right in front of it.
  • Added gain knob to control gain of amplifier stage. In AC coupled mode, the gain pot may be used to amplify the AC component to the level of a few volts. The gain range is 1 to 11. In DC mode, the gain pot may be used to help with faint IR sources; the gain range is 1 to 2.
  • Added a bicolor indicator LED for the CV output.
  • Added an indicator LED for saturation.

Git repo