Long Time Period Automatic Timer

long period automatic timer

As we have already published various timer based project like “Universal Timer”, “Appliance Timer” and many more. Now here is also a timer based project but different in many aspect. The project “Long Period Automatic Timer” offers automatic control of electric and electronics appliance up to long duration.

Circuit Description
The completer project comprise pulse counter IC (IC1) and timer IC (IC2) and few active as well as passive component. Timer IC NE555 (IC1) is configured as astable multivibrator, produce different frequencies controlled by variable resistor VR1. The output of Timer IC (IC2) from pin 3 is given to pin 14 of IC1. Pin 3, 2, 4, 7, 1, 6, 11 offer different frequency selected by switch SW2 as shown in circuit diagram. The main terminal of select switch SW2 is connected to input of Darlington pair made from transistors T1 and T2 through resistor R2. The reset pin of IC2 pin 15 is also connected to main terminal of select switch SW2 in order to reset the circuit. Switch SW1 and SW3 is used to restart and reset the timer respectively.
Table in below shows the appropriate time interval with position of switch

NO.7 5 hours 10 hours
NO.6 4 hours 8 hours
NO.5 3 hours 6 hours
NO.4 2 hours 4 hours
NO.3 1.5 hours 3 hours
NO.2 1 hour 2 hours
NO.1 30 minutes 1 hours

Resistors (all ¼-watt, ± 5% Carbon unless stated otherwise)
R1 = 1 Ω/1W
R2, R3 = 22 KΩ
R4 = 10 KΩ
C1 – C4 = 1000 µF/16V
C5 = 47 µF/16V
C6 = 0.01 µF
IC1 = CD4017
IC2 = NE555
D1 – D3 = 1N4007
T1, T2 = BC147
X1 = 230V primary, 9V - 0 – 9V, 500 mA secondary transformer
SW1 = 1 pole 2 way switch
SW2 = 1 pole 7 way rotary switch
SW3 = push to on switch
RL1 = 9V relay

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