Timer With On-Off Delay

timer with on off delay circuit using ne 555 project

555 Timer With On Off Delay Circuit

Here is a timer circuit using common IC 555. The circuit is designed to facilitate time adjustment of both charged and discharged states of the relay.

timer with on off delay circuit using ne 555

R1 1KΩ
R2 470Ω
C1 100µf 25V
C2 0.01µf
D1 IN4001
D2 IN4001
Q1 SL 100
IC1 NE 555
RL1 12V 400Ω

The circuit uses IC 555 in astable operation. Separate delays for charged and discharged states of the relay are achieved by using two diodes (D1 and D2) and two potentiometers VR1 and VR2 provide control over the ‘on’ and ‘off’ stages of the relay, respectively.

The circuit with given values of VR1, VR2 and C1 provides time periods that are adjustable between a fraction of a second to about one-and-a-half minute approximately.

IC 555 used should be in good condition (preferably a new piece); old ICs can sometimes give wrong results. And capacitor C1 should be of a good make, such as ‘Keltron’ ,’Uptron’ , ‘philips’.

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