Control circuitry for relay - has transistor switch controlled by pulses of appropriate length

摘要

A circuitry for driving a relay comprises a switching transistor (TS1) whose collector emitter path is connected in series with a relay coil (K) connected in parallel with a diode (LD). The transistor (TS1) is driven by a series of pulses whose period is such that the relay is switched on with the min. supply voltage (Us) during a pulse. The pulse frequency is greater than the discharging time of the relay. USE/ADVANTAGE - Digital transmission via relays. Small loss. Allows supply voltage to vary over wide range.