Programmable interval timer circuit - has counter cycled by clock for period fixed by feedback from counter output to clock generator

摘要

A binary counter is coupled to a clock generator to provide a programmable facility for generating signals to a specific time base. The output of a clock generator (2) is coupled over an RC circuit (R1, C1) to the input of a 4 stage counter. The counter cycles through states until the third stage (24) generates an output that is coupled over a feedback path (R2, D1) to the generator. The generator frequency increases to a predetermined value and the counter state increases until the fourth stage (25) outputs. A second feedback (D2) switches off the generator. The method allows a fixed interval output (24) to be generated for a further fixed interval. The technique is suitable for alarm circuit applications.