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.
| PARTS LIST | |
| R1 | 1KΩ |
| R2 | 470Ω |
| VR1 | 1MΩ |
| VR2 | 1MΩ |
| 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’.
Please send your ideas, which are very important for our success…
Can we use 12v instead of 15?
Of course you can.
this circuit i will operate 24 volt relay,what can i do?
Hi,
I made the timer circuit but the relay is not operating as the coil voltage is low it’s 2.8 volts. Please suggest what can I do to rectify it.
check transistor and please use diode (like 1N4001) parallel with the relay. (Diode cathode to positive side , flyback diode – for protection)
this circuit works perfectly.
thanks.
I need the delay off timer after the power on.
It means that whenever the power source connected, the relay is automatic energize within certain period and then back to dis energize.
So delay off timer is just work one time only when after the power source is connected to the circuit.
please your advise me the circuit diagram.
Thank you for your assistance.