Schematics / Serge Triple Wave Shaper
This module is a variation on the 1973 Classic Serge Triple Wave Shaper module.
To quote the 1982 catalog: The Triple Wave Shaper (TWS) is a non-linear modifier which can transform a sawtooth wave into a sine wave. This module incorporates three independent wave shapers for modifying synthesizer waveforms or for processing signals from preamplified instruments. Although originally designed as a wave shaper for our early oscillators, this module has been found to be a excellent modifier of electronic and acoustic sounds, and is highly recommended for subtle timbrel modifications beyond the range of simple oscillator/filter patches.
Of course, it's uses go beyond this. When used in series, they can be used to add folds to the wave shape. Each extra wave shaper you put in series adds a fold to the waveform. As such, quite a lot of tonal variety/harmonic enrichment can be achieve.
visit : http://www.cgs.synth.net/modules/cgs85_tws.html for more details on this module ,BoM ,demonstration and pcb's