Time Delay Relay

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A time delay relay is a relay that stays on for a certain amount of time once activated. This time delay relay is made up of a simple adjustable timer circuit which controls the actual relay. The time is adjustable from 0 to about 20 seconds with the parts specified. The current capacity of the circuit is only limited by what kind of relay you decide to use.

Schematic

Parts

Part	Total Qty.	Description	Substitutions
R1	1	1 Meg Pot
R2	1	10 K 1/4 Watt Resistor
C1	1	10uf 25V Electrolytic Capacitor
C2	1	0.01uf Ceramic Disc Capacitor
D1,D2	2	1N914 Diodes
U1	1	555 Timer IC
RELAY	1	9V Relay
S1	1	1A 120V SPST Switch
MISC	1	Board, Wire, Socket For U1

Notes

R1 adjusts the on time.

You can use a different capacitor for C1 to change the maximum on time.

S1 is used to activate the timing cycle. S1 can be replaced by a NPN transistor so that the circuit may be triggered by a computer, other circuit, etc.

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Comments

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Robert Time Delay Relay Thursday, April 29, 2010 3:11:35 PM

The 555 can sink or source only 200ma, you may have to put a transistor between output pin 3 and the relay.

anonymous Time Delay Relay Friday, April 16, 2010 1:36:53 PM

quote: "hi, i built this circuit it works perfectly when there is no load at the relay, but when i put a load on a relay the circuit works abnormal...pls help me.." maybe the current limit of your power supply is not enough. you can verify this by monitoring the voltage of power supply. decrease on voltage if there is load indicates that the current setting is not enough.

anonymous Time Delay Relay Friday, April 16, 2010 1:33:52 PM

quote: "Hello I have build this circuit but the problem is that there is no delay. if its on it will remain ON and does not turn off. Please help Thx and Regards" troubleshoot your circuit. voltage at pin 6 should be rising the minute power is applied. if voltage is not increasing, adjust R1 to a lower value.

anonymous Time Delay Relay Friday, April 02, 2010 6:30:55 AM

Sir, What is that 1 Meg 'POT' means ? WHAT IS THE OUTPUT BEING DISPLAYED IN THIS CIRCUIT?please reply sir.

Waqas Time Delay Relay Tuesday, August 25, 2009 4:52:29 AM

Hey this is a really nice and easy circuit to follow, but i was wondering if this can be applied to a 220v supply?? As i want a delay in my power when the relay detects another power source.

anonymous Time Delay Relay Monday, August 17, 2009 6:32:00 AM

hi, i built this circuit it works perfectly when there is no load at the relay, but when i put a load on a relay the circuit works abnormal...pls help me..

AB Time Delay Relay Monday, August 10, 2009 11:29:41 PM

I have the same problem as Mohsin - power up and relay turns on and the circuit closes. This occurs without the switch. As soon as power applied relay trips and stays on until power removed. Is there a common error that I might look for in my build?

Mae Time Delay Relay Sunday, August 09, 2009 10:55:30 AM

circuit is not working to me :( can anyone tell me where am i making mistake...all components new...

Mohsin Time Delay Relay Monday, June 08, 2009 11:54:05 PM

Hello I have build this circuit but the problem is that there is no delay. if its on it will remain ON and does not turn off. Please help Thx and Regards

WillyAG Time Delay Relay Saturday, June 06, 2009 5:58:27 PM

For timed relay action when the entire circuit is powered up, I put a capacitor (10uf) in place of the switch. On power up, the relay swirtches on for 10 seconds then off for as long as the circuit has power. Thanks for the info, the circuit you designed works perfectly. The fact that you would spend the time helping others is what's really good about the Internet.

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Robert	Time Delay Relay	Thursday, April 29, 2010 3:11:35 PM
The 555 can sink or source only 200ma, you may have to put a transistor between output pin 3 and the relay.
anonymous	Time Delay Relay	Friday, April 16, 2010 1:36:53 PM
quote: "hi, i built this circuit it works perfectly when there is no load at the relay, but when i put a load on a relay the circuit works abnormal...pls help me.." maybe the current limit of your power supply is not enough. you can verify this by monitoring the voltage of power supply. decrease on voltage if there is load indicates that the current setting is not enough.
anonymous	Time Delay Relay	Friday, April 16, 2010 1:33:52 PM
quote: "Hello I have build this circuit but the problem is that there is no delay. if its on it will remain ON and does not turn off. Please help Thx and Regards" troubleshoot your circuit. voltage at pin 6 should be rising the minute power is applied. if voltage is not increasing, adjust R1 to a lower value.
anonymous	Time Delay Relay	Friday, April 02, 2010 6:30:55 AM
Sir, What is that 1 Meg 'POT' means ? WHAT IS THE OUTPUT BEING DISPLAYED IN THIS CIRCUIT?please reply sir.
Waqas	Time Delay Relay	Tuesday, August 25, 2009 4:52:29 AM
Hey this is a really nice and easy circuit to follow, but i was wondering if this can be applied to a 220v supply?? As i want a delay in my power when the relay detects another power source.
anonymous	Time Delay Relay	Monday, August 17, 2009 6:32:00 AM
hi, i built this circuit it works perfectly when there is no load at the relay, but when i put a load on a relay the circuit works abnormal...pls help me..
AB	Time Delay Relay	Monday, August 10, 2009 11:29:41 PM
I have the same problem as Mohsin - power up and relay turns on and the circuit closes. This occurs without the switch. As soon as power applied relay trips and stays on until power removed. Is there a common error that I might look for in my build?
Mae	Time Delay Relay	Sunday, August 09, 2009 10:55:30 AM
circuit is not working to me :( can anyone tell me where am i making mistake...all components new...
Mohsin	Time Delay Relay	Monday, June 08, 2009 11:54:05 PM
Hello I have build this circuit but the problem is that there is no delay. if its on it will remain ON and does not turn off. Please help Thx and Regards
WillyAG	Time Delay Relay	Saturday, June 06, 2009 5:58:27 PM
For timed relay action when the entire circuit is powered up, I put a capacitor (10uf) in place of the switch. On power up, the relay swirtches on for 10 seconds then off for as long as the circuit has power. Thanks for the info, the circuit you designed works perfectly. The fact that you would spend the time helping others is what's really good about the Internet.