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How to build Wide Range Timer
August 8, 2010 - category: TimerDescription
A wide rage auto turn OFF timer covering 1 minute to 20 hours in three ranges with S1. As soon as power is applied to the circuit the IC1 [555] starts to oscillate happily and feeds clock pulses to the IC2 [4017]. The IC2 [4017] and IC3 [4020] give a combined count rate of 81920 before the output of the IC3 [4020] goes high and turns Q1 on. With pot RV1 adjust the Time.
Circuit diagram
Part list
- R1=2.2Kohm
- R2=39Kohm
- R3=1Mohm
- R4=27Kohm
- R5=12Kohm
- R6=6.8Kohm
- C1=120nF 63V polyester
- C2=1.2uF 63V polyester
- C3=100nF 63V
- RV1=470Kohm pot.
- D1-2=1N4001
- IC1=LM555
- IC2=4017B
- IC3=4020B
- Q1=BC214
- S1=2X3 SEL SWITCH
- S2=Push button no
- RL1=12V >120ohm Relay
circuit from http://users.otenet.gr/~athsam/wide_rage_timer.htm
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