Auto-octaver oscillator with pulse width control

The base oscillator is composed of two NOT-gates, which I use as a stand-in for a schmitt-trigger inverter. The frequency is determined by the capacitor combined with the pot that connects in between the not gates. The pulse width is determined by the resistance in each direction. The diodes separate it so that it can be tuned. This then goes directly to the input of a 2-channel multiplexer and to a row of flip-flops that are a stand-in for a binary counter. Each flip flop halves the frequency. The first and second staged of the flip-flop row are connected with a switch and then to the other input of the multiplexer, which gives either 1/2 frequency or 1/4 frequency, 1 or 2 octaves down. The last flip flop is connected to the input switch of the multiplexer so that it switches between the original frequency and 1/2 or 1/4 of the original frequency. If this were to be done elsewhere, I’d use a CD40106 as the oscillator, a CD4040 as the binary counter and a CD4051 as the multiplexer! It’s basically a simplified copy of most of the logic noise synths out there, but with minor modifications.

published 5 years ago