keep

Keep, was made as a companion to bastl instruments ‘kastle 1.5’ synth.

It’s a self-modulating modular analog synth based on the ancient XR 2206 IC, which you can still buy (in china) :)

I make limited numbers and offer a kit for sale. The kit is 50 Euro and built 86 Euro. Batteries not included :) See below for what is included.

Here the keep is driving a cv input on the rampart.

Here is a complex example of self-sequencing :)

Open hardware

Open Sources includes several versions as fritzing files. The breadboard and schematic views are messy. Working on it.

The keep and kastle together.

Hacking

Keep was also designed to be able to be fun to hack: here with a capacitor being fed audio output and back into the FM for channel a….

The kit

The kit is pictured below.

What’s in the kit?

• 1 40106 (+ 1 spare!)
• 1 CD4040E (+ 1 spare!)
• 1 XR2206 frequency generator
• 1 Audio Jack (TRS) 3.5mm
• 4 Ceramic Capacitors
• 4 Electrolytic Capacitor
• 1 100kΩ Resistor
• 1 1kΩ Resistor
• 1 220Ω Resistor
• 2 330Ω Resistor
• 6 4.7kΩ Resistor
• 10+ Custom female headers - 2 pins - 10 pins
• 1 DIY Vactrol
• 1 Barreljack Power plug
• 1 LED (+ 1 spare!)
• 2 Top and bottom PCB
• 4 Silicon feet
• 9 Rotary Potentiometers
• 9 Pot Knobs
• 1 9volt to barreljack plug
• 12 mini jumper cables of various lengths and color

some more media files

An older recording of the keep solo.

The keep torturing a korg micro modular :)

The keep and rampart together.