Fritz Jerkster Chaos

Quantity: 1

Description: Ian Fritz’s circuit produces chaotic oscillations according to a third-order differential, or ‘jerk’, equation.  The panel, bracket, and PCB are available from Bridechamber:

Fritz Jerkster Panel

Three Jack Bracket

Fritz Jerkster PC Board

Ian’s page:

The Jerkster

In as simple terms as I can describe, there are three outputs, each of which produces sinusoidal waveforms.  The outputs have some correlation, especially the frequency.  The frequency range is pretty wide.  I have used it so far in the LFO range, where it is great for spooky vibrato, and in combination with a comparator produces interesting random gates.  I don’t understand just what the MOD CV modulates, but it changes the character of the outputs.  In fact, I can’t say I understand this module much at all!  But it’s a good source of  smoothly varying random voltages.

Here is a detail of the circuit board.  The PC board is not high quality, but it’s a simple circuit.  It was a bit of a chore to file down the pins on a MOTM power connector to fit the too-small holes in the board.  I ran a wire soldered to the ground pins at the power connector out to ground the panel jacks and did not use the tiny ground pad – pin 15.  Although you could use a 16-pin header and a connector, it seemed too much trouble, so I just soldered wires into the header pin holes.

Here is another picture of the construction.  I used inexpensive Alpha carbon pots, the shafts fitted with #5 O-rings from Lowes plumbing department to seat them into the 3/8-inch panel holes.  After finding that the Rate pot has a large range and is very sensitive, I am considering replacing it with a 10-turn pot.  The Bridechamber 3-jack bracket works, but despite having a lot of holes to match various PC boards, none matched the Jerkster and I had to drill my own.  I cut off the unused portion of the very long bracket.


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