The ALM Busy Circuits ‘Fizzle guts’ is a Eurorack dual low pass filter and VCA that uses a ‘donor’ filter MB87186 chip from a Casio FZ1 sampler. It was originally designed in 2014 as a fun side project and only approx 30 of the original units were made. With no plans to make any more, we have open sourced the pcb design files (eagle), avr microcontroller code and a basic panel design so others can make there own and add customisations and/or improvements.
A built module features two filter cores A & B with voltage and direct controlled resonance and cut off as well as a ‘DCA’ (a digital controlled vca). There is also a mix output. Expect a weird murky sounding filter which can squeek and blip when modulated but can really squelch up nice.
You will need a donor ‘MB87186’ IC desolded from a real FZ1 or FZ1M synth. They each contain 4 and the IC is usually marked ‘FM1’ with a date code below. The IC then connects to the DIL socket on the rear of the module.
For more information on the MB87186 (and from what much of the code was based on) see http://www.buchty.net/casio/dcf.html
PLEASE NOTE EVERYTHING IS PROVIDED AS IS. WE ARE UNABLE PROVIDE ANY SUPPORT TO ANYONE ATTEMPTING TO USE THESE FILES
You’ll need a basic ‘usbtiny’ AVR programmer.
You’ll need to install avr-gcc and avrdude.
(On mac using brew..)
brew tap osx-cross/avr brew install avr-gcc brew install avrdude
Type ‘make’ in the firmare/ directory to compile the source code and then run ‘./flash.sh’ (with your programmer connected) to program the Fizzle.
Code: MIT license.
Hardware: cc-by-sa-3.0
ALM is a registered trademark.
The name “ALM” should not be used on any of the derivative works you create from these files.
We kindly ask to do not name any derivatives ‘FIZZLE GUTS’ but give it a new name.