Squarewave generator with digital frequency setting

A crystal-controlled squarewave generator is described which operates on the phase-locked-loop principle. It delivers pulses in the range 1 to 10 MHz, adjustable in steps of 1 kHz. The input of the nominal frequency is performed digitally with multiswitches or by means of signals with TTL levels. The circuitry principle can be used quite generally in cases where crystal-controlled pulse generators are required with continuous frequency setting.