Synth Project

flicr set by marinedalek

"My AS Design & Technology project - a simple synthesiser built from analogue chips and digitally controlled (vaguely!)"

some info from this electro-music.com thread:
"It's a triangle-core synth based on a simple op-amp integrator design. Not having time for lots of prototyping I took the rather odd route of making it resistance-controlled rather than voltage-controlled. Each keypress on the copper touch-sensitive keyboard triggers a reed relay that switches in the tuning pot corresponding to that note. There's also a variable rate and length "sequencer" which plays each note of the keyboard in turn - by entering non-standard tunings various riffs can be programmed in.

As far as sound shaping goes, there's a PWM section with its own LFO driven by the triangle core, as well as pure triangle and square waves, with divided -1oct and -2oct square waves also included. Filtering is very basic, just two 6db/oct buffered passive lowpass/highpass combinations, which can be chained in series for stronger filtering.

Initially there were going to be two additional oscillators with non-keyboard-controlled tuning for fun swoopy sound effects, which is why I included 2 filter sections (one for osc1, the second for the other 2 oscillators). The first of these was to be a saw/pulse oscillator, and the second a sine/square oscillator - however time constraints meant these were never built

During construction a fault developed which means the output is extremely distorted (~infinite gain) with a lovely DC offset just to make it even more unpalatable. I'm hoping to fix this some time when I get some equipment set up."