Make up your mind, already. Ambivalence Drive is here to help. Built around a DG419 analog switch, Ambivalence Drive uses control voltage to switch between two input signals, routing to a single output.

Use the toggle to choose between a constant 5v reference or a variable voltage set with the Voltage Range knob. The constant reference can be used to control the switch with a gate/trigger/clock signal. Whereas the variable voltage knob can dial in a specific voltage reference, allowing for things such as using the CV from a sequencer or S&H to switch between oscillators when the note is above a certain frequency.

Patch another audio source into the CV input and the Ambivalence Drive functions just like the Thunderdome.


Schematics are provided as-is. Never trust that any schematic on the internet is foolproof. Test your build in isolation before introducing it to the rest of your modules.


  • Capacitors
    • 30pf ceramic capacitor (1) C8
    • 10uf ceramic capacitor (5) C3, C4, C5, C6, C7
    • 10uf electrolytic capacitor (2) C1, C2
  • Resistors
    • 300R resistor (1) R4
    • 1k resistor (1) R5
    • 2.7k resistor (2) R1, R3
    • 24k resistor (1) R2
  • Potentiometers
    • 20k single-turn trimmer (1) R1
    • A100k (2) RV3, RV4
    • B100k (1) RV2
  • Transistors
    • 2n3904 transistor (1) Q1
  • ICs
    • TL074 op amp (1) U2
    • DG419 analog switch (1) U3
    • L78L05 5v regulator (1) U1
  • LED (1) D1
  • Eurorack power header (1) J1
  • Audio jacks (4) J2, J3, J4, J5
  • SPDT toggle (1) SW1

Calibration Notes

The 20k trim pot in the Reference Voltage section is used to set a minimum voltage threshold. The switch requires some level of voltage at the reference pin, otherwise it will never trigger. To calibrate, turn the Voltage Range knob fully counterclockwise and adjust the Voltage Trim until the Ref Volt output is 0.5v


Rhythm & Lead demo
Timed Alternations demo (first with clock divider for 1:1 switching; then without for 2:1 switching)
Choppy Rhythm demo

Patch Ideas

Timed Alternations

Simple patch to alternate between two sound sources, in time with a clock source.

  • Patch oscillator 1 into input 1
  • Patch oscillator 2 into input 2
    • Alternatively, patch two different waveforms from the same oscillator
  • Patch clock into CV input

Note: When the voltage is low, the first input passes through the switch. When the voltage is high, the second input passes through the switch. For every clock pulse, the voltage starts low, goes high, then goes low again. So, for every clock pulse, you will get one note from each oscillator, in what sounds like double time. To alternate so that only one note plays for each step, use a clock divider.

Rhythm & Lead

Alternate between bass and lead using the same sequencer or randomly-generated set of notes.

  • Patch a sine wave into input 1
  • Patch a saw wave, tuned two octaves higher, into input 2
  • Patch CV from a sequencer into both oscillator 1v/oct inputs, and into the CV input of Ambivalence Drive
    • Alternatively, use a Sample & Hold module instead of a sequencer–patch the CV out into the same inputs listed above
  • Set the Voltage Selection to variable and dial the Voltage Range knob until the lower notes of the sequencer are playing on the sine and the higher notes are switching over to the saw

Choppy Rhythm

Replicate a gated sequence, where certain notes are skipped.

  • Patch oscillator into input 1
  • Leave input 2 empty
  • Patch CV from a sequencer into the oscillator 1v/oct input and into the CV input of the Ambivalence Drive
    • Alternatively, patch the CV output of a Sample & Hold module to create randomish patterns
  • Program the sequencer so that some notes are outputting at maximum voltage (these will be the notes that are skipped)
    • Depending on the maximum voltage output of the sequencer, set the Voltage Selection to constant 5v, or set to variable and adjust the Voltage Range knob until the desired notes are skipped

Thunderdome (But Not Really)

Works like the Thunderdome, except three sounds enter and one sound leaves…

  • Patch oscillator 1 into input 1
  • Patch oscillator 2 into input 2
  • Patch oscillator 3 into CV input