Spongillator, a sponge based audio oscillator

Details

Description

Sponge material shows an extremely large dielectric constant that changes with the amount of compression. Becomes a variable capacitor when clamped between two metal plates, here enabling wide range sweeping of an oscillator and a filter. Pressure controlled capacitors changing from 1nF to 100nF can be made with only a few cm^2 of (cellulose based) sponge material, suggesting dielectric constant values above 1000. Note that this concept differs completely from the common resistive based pressure sensors.
This movie shows a sponge-based oscillator and a sponge-based lowpass filter as an introduction into "Spongetronics". Comes with oscilloscope waveforms showing RC-times from the variable capacitance and resulting sounds. More details and info on Elektor Labs:
https://www.elektormagazine.com/labs/spongillator-a-sponge-based-oscillator

See all my projects on Elektor Labs:
https://www.elektormagazine.com/labs/123619/rs-elc/projects
And on my personal website: www.RS-elc.nl