Variable pulse generator circuit - uses shift register to allow output at one of two frequencies with variable mark space ratio

摘要

A pulse generator circuit allows an output frequency to be produced that is a function of two selected frequencies. The mark/space ratio of the output pulse train may also be selected. The circuit is based upon two shift registers, of 'm' stage lengths, one of which is bi-directional. Each register is clocked with separate clock pulses of different frequencies (F1, F2). The mark/space ratio is determined by the state of the preset input is fixed by gating stages. The output frequency is obtained for a gating circuit coupled to the uni-directional register. A switching stage decides which of two frequencies is generated.