Control circuit for motor - has tachometer coupled to comparators connected to integrated circuit controlling triac

摘要

The control circuit comprises an integrated circuit coupled to a tachometer and controlling a triac. The tachometer's output voltage is proportional to the motor's speed and is compared (31) with a control voltage passed via a delay circuit (26,27). The speed-proportional voltage is applied to one input (P4) of the comparator (31) and the delayed control voltage to the other input (P5). The output of the comparator output (P2) passes via a delay (37,38) to the input (P6) of a second comparator (30) where it is compared with a reference voltage (P7). The second comparator's output (P1) is connected to the integrated circuit (6) to control the generation of turn-on pulses for the triac (2).