LoFI Future - OctoTron Expander
PCB Design for the 8-Step Sequencer is almost done, Im calling this thing the OctoTron Expander. This sequencer is very primitive. As you will notice there are no step on/off switches and no transistor outputs to pull a proper gate from. It has simply one voltage output. The KORG Monotron likes to receive CV via gate for some reason, so sending this one voltage in to the monotron works just fine. You can also send this voltage into the cut off CV and modulate it, there is an on board switch to send the sequence to the pitch or cut off. The steps can be turned of by turning them all counter clockwise. This is possible thanks to a dead spot in the 1n914 diodes, when the pots are turned down, the 1n914 drops out all the voltage and basically breaks the connection, just like a switch.
On board 9V and 3V regulators lets the sequencer and monotron run off of a 12V wall wart. Sync in is conditioned and wired to connect into the internal 555 clocks trigger input. It can accept basically anything you throw at it, from a TR626 clock to a line level audio signal.
This board is designed to be mounted via its pot and 2 PCB standoffs from a custom cut panel that will also host the monotorn on 2 PCB standoffs and a supporting bracket.
What this means for the builder, is an easy assembly that could be accomplished within half a day.
This will work with all 3 monotron models. With the DUO its really nice since the voltage from the pots is pitched quantized in key.