Time delay circuit for relay - has three transistors and two diodes connected to relay winding and power supply

摘要

A time-delay circuit for a relay has a charging capacitor (C), three transistors (T1, T2, T3) and two diodes (D1, D2). The collectors of the second and third transistors are connected to the same end of the relay winding, the other end of the winding being connected to the supply terminal. The make contact (t) of the relay is connected to the driving circuit and to the collector of the first transistor (T1) via two resistance (R4, R5) in series. A diode is connected between the charging capacitor C and the base of the first transistor T1.