Digitally Controlled Oscillator Schematic : For information on what a DCO is – Please see my other page on DCOs.
Version 1 DCO design:
Showing is one full voice, certain components have extra parts, such as the 4013 flip flop. Therefore we can use these for a second voice on the same circuit board.
Op amps require a supply voltage of +15 volts, -15 volts or -5 volts (either negative rail depending on final design)
Shown are 2 designs for level shifters, The 4066 switch is switching higher voltage waveforms (~10volts). Therefore we need 15 volt control signals.
The MAX 333 switch is very universal, accpting 5 volt control signals on a 15 volt power supply.
Choosing this over 4053 chip is because it’s a quad and fit with the design of a dual oscillator per PCB and handles the modulation routing.
The FET VCA can be replaced with an AS3360, It’s there for cost saving but it’s not as good as the 3360 for a VCA.
Anyone interested in building this design from my digitally controlled oscillator, please contact me if you require any help.
Of course this is an experimental design and any experimenting done at your own risk.
This DCO contains only one oscillator, a sub octave is included to give the sound a fatter tone. Dividing the square wave by 2 always gives you an octave down. Music is good like that. Octave vs frequency is just multiplied or divided by 2!