Description

Ilse is an elegantly minimal, yet fully functional synthesiser voice in a compact 10 HP Eurorack module. The only thing you need to let it meow is a CV source to trigger its 1V/Oct frequency input (or a MIDI to CV converter and a MIDI sequencer).

Ilse is named after a cat, living in the legendary “Villa” in Weimar, Germany. The “Villa” was a place where a community lived and came together. Many underground concerts and parties took place here before the house got sold, renovated, and the mayor moved in. The graphics on the aluminium face-plate were created in her memory. Ilse (the synth) makes great acid sounds, so it was only logical to illustrate a cat tripping. Turn the knobs to make her look around or roll her eyes.

Ilse is designed to be affordable, easy to build, yet flexible, and feature rich. It is a synthesiser voice for your Eurorack, but can even be driven without a rack using two 9V batteries (not included).

Ilse is fully open source (KiCad schematic and layout is available in a git repository) and inspired by Syntherjack’s single-chip synthesiser Totoro. Check out his website for some nice explanations, e.g. on the filter ( the same filter is used on Ilse). The design is extended for external voltage control on the filter, oscillators and LFO. Unlike Totoro, Ilse is designed around a unique oscillator, which integrates the exponential conversion directly into the oscillator core. This results in more efficient circuitry saving you build time, parts and costs.

PCB and face-plate are manufactured in the EU. Kitting was done by Befaco in Barcelona.

Functions

• Two saw tooth oscillators
• Bridged-T low pass filter with resonance control
• Triangle LFO with speed control, and routing to filter and/or oscillators
• Simple mixer and detune for oscillators

Controls

• LFO Speed, Filter Modulation, Osc Modulation
• Filter Cutoff, Filter Resonance
• Tuning, Osc2 Detune
• Osc1/Osc2 (Filter in)
• Output volume

Input/Output

• 1V/Oct CV for oscillators (0-5V)
• Gate (0-5V)
• Filter cutoff (0-5V)
• External filter input
• Volume controlled output
• LFO Speed (linear, via solder pad on back, 0-8V)
• Oscillator 2 detune (linear, via via solder pad on back, 0-8V)

Specs: 

Width: 10HP
Depth: 23mm
Power Consumption: 22 mA +12V, 18 mA -12V

Ilse – Build Document | Schematic