Garbage Collector – MIDI Expression and Switching Device

The Oscillator Devices Garbage Collector is a series of MIDI to expression converter and MIDI footswitch emulators. Control up to four effects devices with expression pedal inputs or inputs for external foot switches (e.g. tap tempo) via MIDI. Garbage Collectors can sync to MIDI clock, allowing time-based effects to sync to either tap tempo (MIDI footswitch emulator) or LFO waveforms (MIDI to expression converter).


  • MIDI to expression converter with up to four expression outputs
  • MIDI footswitch emulators with two switches per TRS
  • High voltage and AC switching with isolated GND
  • MIDI clock synchronous LFO waveforms for modulation of the MIDI to expression converter
  • MIDI clock synchronous switching of the MIDI footswitch emulators
  • Multicolored LEDs for status indication
  • Presets and choice of start configuration
  • Selectable MIDI channel
  • Compatible with all MIDI 1.0 compliant controllers
  • High-quality Amphenol sockets
  • Developed and handbuilt by Oscillator Devices in Germany

Differences between the models

OutputsEXPSwitchesEXP InputMIDI ThruAC-SwitchingDimensions*
v3224NoYesYes69 x 54 x 24 mm
Mini112NoNoYes54 x 41 x 24 mm
EXP440YesYesN/A119 x 94 x 34 mm

*Dimensions of the enclosure without sockets

Garbage Collector v3 and Garbage Collector Mini

TRS-Socket of the Garbage Collector 3 and Mini
TRS-Socket of the Garbage Collector v3 and Mini

The Garbage Collector v3 and Garbage Collector Mini both have 1/4″ stereo jack sockets that work as MIDI to expression converter, as well as MIDI controlled footswitches. If the expression function is activated via MIDI command, the switch automatically deactivates. If the switch is used, the expression function switches off automatically.

The switches can be isolated from GND and disconnected from the expression function. That way amplifiers or other external equipment can be connected without the risk of ground loops. With the expression function disabled, the Garbage Collectors can switch negative voltages and voltages of up to ±60V.

See some example connections below. Note, that TRS1 and TRS2 of the Garbage Collector v3 have the exact same capabilities.

Example connections of the Garbage Collector Mini (l.) and Garbage Collector v3 (r.)


The associated LEDs make the setup easy. With the switch function, the LEDs light up whenever the contact is closed. The green LED lights up whenever the tip is connected to the sleeve, the red LED lights up whenever the ring is connected to the sleeve. When using the expression function, the LED on the heel position lights up green, gets darker towards the middle position and begins to light up red when it comes to the toe position.


There are up to 16 presets. The current switch and/or expression state is saved and then called up with a single Program Change command later. For saving a preset, simply call the CC command for preset saving. The last command that was called for each TRS is then saved. You can even set your startup configuration with saving to the first preset.

Config Switch

There is a small hole in the back with a switch in it. You can use it for setting the MIDI channel, as well as testing the outputs without a MIDI controller. Press the switch shortly while the device is switched on, tip, ring and tip+ring are closed in sequence. Hold the switch and the expression function is activated and is slowly moved from heel to toe and back again. For setting the MIDI channel hold the switch while powering up and press the switch according to the number of the MIDI channel you want. Hold again to save.

Garbage Collector EXP

The Garbage Collector EXP is an entirely different beast. It features four expression outputs that can be controlled by an expression pedal and by MIDI at the same time.

Example connections of the Garbage Collector EXP

With the two footswitches, you can cycle through the four expression outputs and choose which one is controlled by the expression pedal connected to the expression input. Alternatively you can set up one of the 8 presets and control every possible combination of the expression outputs at the same time. You can even invert heel and toe position individually.

Of course the Garbage Collector EXP can be used as MIDI only device, without an expression pedal. Every expression output can be controlled individually by CC commands, or can be driven by the integrated LFO waveforms.


All three Garbage Collectors have an internal, MIDI clock synchronous, LFO engine with three different waveforms to drive the MIDI to expression converter. Choose between sine wave, square wave or saw tooth in both directions. The speed of the waveforms depends on MIDI clock, with one pass being either whole, half, quarter, eighth, or sixteenth notes. The waveforms can be further altered in starting point, amplitude and position.

Waveforms for the MIDI to expression converter
Three different waveforms: sine, square and sawtooth (forward and backward)

MIDI Connection

The MIDI sockets are assigned according to the official MIDI specification of MIDI TRS using MIDI TRS Type A, like pedals from Boss or Wampler. A 1/8″ (3.5 mm) stereo jack plug is used. The MIDI Thru socket is latency-free.

MIDI TRS Type-A to DIN 5-Pin
1/8″ stereo jack plug to DIN 5-Pin according to MIDI TRS Type A




Quick ReferenceGarbage Collector v3 and Mini (January 2024)PDF
User ManualGarbage Collector v3 and Mini (January 2024)PDF
User ManualGarbage Collector EXP (September 2023)PDF