Spin Semi

Molecular Compactor (Spin Semi FV-1 based)

Seems like having 2 Molecular Disruption Devices with 8 programs each was getting too little … so I decided to build another one. Since I did not need the expression pedal and tap switch as much as I would have thought I made a new layout for a smaller version.

Same circuit as the MDD minus the tap switch, tap switch option control and expression pedal input.

Quite happy with the smaller footprint and reduced number of options (choices, choices …)

Molecular Disruption Device – Spin Semi FV-1 based multi-effect

This circuit is built around the Spin Semi FV-1 DSP chip.

This (too long) demo shows some programs I have been working on:

Most of the effects were created with the great SpinCad software created by Digital Larry. Some are parts of available code stitched together (still have a lot to learn in that respect)

Apart from the circuitry supporting the FV-1 chip, you can see an input buffer and a mixing stage mixing the buffered direct signal with the output of the FV-1. The hardware mixing works fine in most cases and avoids dedicating one of the 3 pots controlling the FV-1 parameters. Sadly with some programs where the signal coming from the FV-1 is too similar to the direct signal, there is some phasing effect because of the very slight latency introduced by the DSP.
I also added a hardware feedback path that takes the right output of the FV-1 and feeds it back to the right input through a pot.

The 8 programs loaded in the external EEPROM are selected with an 8 position rotary switch and a network of diode logic.

The POT0 input on the FV-1 is connected to either a pot or the jack for external expression input. A momentary switch is also inserted to this input. A 4 position rotary selects between the use of the pot or expression input each time with the option to have the momentary switch going high or low.

I added the momentary switch mainly to use it for an infinite reverb effect (freeze) and also for tap tempo.

There is a 3 pin connector on the PCB to allow programming the EEPROM in circuit.