skunks Posted July 13, 2017 Report Share Posted July 13, 2017 I don't quite understand the theory behind this. Maybe someone could advice me an article or explain briefly. Why most of analog oscillators are very sensitive to temperature and tuning them is a real challenge while SID is not? Quote Link to comment Share on other sites More sharing options...
latigid on Posted July 13, 2017 Report Share Posted July 13, 2017 Oscillators are not inherently unstable, but our hearing means we perceive pitch exponentially. So from one octave to the next means a doubling in frequency. If you want to control pitch on a VCO linearly (commonly 1 volt per octave), then you need an exponential converter for your keyboard or MIDI data. Most of these circuits have a temperature coefficient that is always present. Digital oscillators just count a number of divisions of the master clock. Quartz resonates at a very specific frequency, and so it's much easier to count pulses this way. I think the SID uses a lookup table to derive the oscillator frequency. Quote Link to comment Share on other sites More sharing options...
skunks Posted July 14, 2017 Author Report Share Posted July 14, 2017 I suspected it is so :-) I also looked through a soviet electronic accordion Estradin schematic. It has 12 tone generators heavily stuffed with logic elements. Quote Link to comment Share on other sites More sharing options...
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