digital oscillators - enthusiasts for music

digital oscillators elektor june 1985 enthusiasts for music digital oscillators One of the real problems in electronic organs, synthesizers, and other polyphonic instruments is the stability of the oscillators, and the more oscillators there are, the more important tight tolerances become. Every hobbyist who has ever worked on a circuit containing a number of oscillators will know what we mean. One of the methods used to solve (or avoid) this problem is the use of digital techniques and a crystal to determine the frequency. Unfortunately, this procedure brings with it a fixed phase relation between separate signals, which detracts from the naturalness of the sounds. As we were not satisfied with this, we designed three circuits that may be used to replace the voltage-controlled oscillator (VCO) in an existing design, or that may form the basis of a new design. The duty factor of a digital (pulse) signal is the ratio of the pulse width to the pulse spacing. It is sometimes, quite w...