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L37, 5 - 30 Minute Timer circuit

A switched timer for intervals of 5 to 30 minutes incremented in 5 minute steps. Configured by Monostable of 555. Simple to build, simple to make, nothing too complicated here. How-ever you must use the CMOS type 555 timer designated the 7555, a normal 555 Timer will not work exactly here due to the resistor values, but First you should try with normal 555 then 7555. Also a low leakage type capacitor must be used as for C1. When switch S1 is push, pin2 get a trigger pulse and output comes on pin3. And relay will operate. You can connect any home appliances to relay. Like table lamp, table fan etc.


  • 555 Timer IC

  • Transistor BC109C

  • Capacitors C1 = 3uf, C2 = 100nf,

  • Diode D1 = 1N4007

  • Resistors R1-R8 = 8.2M, R7 = 4.7K, R8 = 100K

  • Relay 9volt or 6volt

  • Switches S1, S2 & S3

  • 9volt Battery

NOTE; In any case, circuit doesn’t work, connect pin 5 to the ground with a series capacitor of 0.01uf value, and remove capacitor C2.

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