20 hour timer relay circuit with 4017,4020

20 hour timer circuit

up to 12 hours or more.
Can be used as a repetition timers – or timers at once.
Both circuits are mainly the same thing. The main difference between them and their behavior
single shot. Mode switch S2 is set to below
1-1 in 12 minutes
2-10 min to 2 hours
3-100 min to 20 hours

In one stroke – when the set time has elapsed – Version
1 energizes the relay and Version 2 de-energizes the relay.

These 2 circuits are multi-range timers offering periods

 The first uses less energy, while the timer is running – and
second uses less energy, after the timer has stopped. Choose
one that best suits your application.

Electronic  parts List
R1 = 2K2
IC1 = 555timer
R2 = 39K
IC2 = 14017, decade counter
R3 = 470K (pot)
IC3 = 14020, divider
R4 = 1M
Q1 = 2N3906
R5 = 27K
D1 = 1N4001
R6 = 6K8
D2 = 1N4001
C1 = 0.12µF, ceramic
S1 = Push switch, momemtary on
C2 = 1.2µF, polyester
S2 = 3-step/2-deck rotary switch
C3 = 0.1µF, ceramic
Ry1 = 12V