Simple Delay Timer Circuits Explained

In many electronic circuit applications a delay of a few seconds or minutes becomes a crucial requirement for ensuring correct operation of the circuit. Without the specified delay the circuit could malfunction or even get damaged.

Here we discuss how we can make simple delay timers using very ordinary components like transistors, capacitors and diodes.

Let's analyze the various configurations in details.

The first circuit diagram shows how a transistors and a few other passive components may be connected for acquiring the intended delay timing outputs.

The transistor has been provided with the usual base resistor for the current limiting functions.

A LED which is used here just indication purposes behaves like the collector load of the circuit.

A capacitor, which is the crucial part of the circuit gets the specific position in the circuit, we can see that it's been placed at the other end of the base resistor and not directly to the base of the transistor.

A push button is used to initiate the circuit.

On depressing the button momentarily, a positive voltage from the supply line enters the base resistor and switches ON the transistor and subsequently the LED.

However in the course of the above action, the capacitor also gets charged fully.

On releasing the push button, though the power to the base gets disconnected, the transistor continues to conduct with the aid of the stored energy in the capacitor which now starts discharging its stored charge via the transistor.

The LED also stays switched ON until the capacitor gets fully discharged.

Te value of the capacitor determines the time delay or for how long the transistor stays in the conducting mode.

Along with the capacitor, the value of the base resistor also plays an important role in determining the timing for which the transistor remains switched ON after the push button is released.

However the circuit using just one transistor will be able to produce time delays which may range only for a few seconds.

By adding one more transistor stage (next figure) the above time delay range can be increased significantly.

The addition of another transistor stage increases the sensitivity of the circuit, which enables the use of larger values of the timing resistor thereby enhancing the time delay range of the circuit.


Two Step Sequential Timer

The above circuit can be modified to produce a two step sequential delay generator. This circuit was requested by one of the avid readers of this blog, Mr.Marco.




A simple delay OFF alarm circuit is shown in the following diagram. 

The circuit was requested by Dmats.

The following circuit was requested by Fastshack3

"I am looking to build a circuit that would control an output relay. This would be done in 12V and the sequence will be initiated by a manual switch. I will need an adjustable time delay (possibly displayed time) after the switch is released, then the output would go on for an adjustable time (also possibly displayed) before shutting off. The sequence would not restart until the button was pressed and released again. The time after the button release would be from 250 milliseconds to 5 seconds. The "on" time for the output to turn on the relay would be from 500 milliseconds to 30 seconds. Let me know if you can offer any insight. Thanks!"


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156 comments

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Anonymous
May 4, 2012 at 7:07 AM delete

Good day, can please make me a circuit similar to above but in reverse. A circuit that will switch off the relay in 2 minutes after giving a power.

thanks

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May 4, 2012 at 9:02 AM delete

Good day to you, just remove the capacitor from its position and put it in place of the switch, positive will to the positive, and the negative will go the resistor 2m2.

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Anonymous
May 4, 2012 at 10:45 AM delete

success, adjusted some resistors too. thank you very much

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May 4, 2012 at 10:59 AM delete

hi,
pls help me to make some modifications to this ckt. i used a relay in this ckt with relay drive trasistor and is working. i need this ckt as, Once the relay get on, it should remains ON condition even we off the push switch.ie, when we on the switch, relay should get ON after the set delay and later on ,relay should remains ON condition for ever until total supply is disconnected.and push swich should not have any effect after the initial ON of relay.hope my requirement is clear. kindly help with a simpe circuit.

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May 4, 2012 at 12:01 PM delete

Hi,

Though I couldn't clearly understand your question, I guess you are asking for a latch circuit.
Connect a 100K resistor across the collector of BC557 and the base of BC547, remove the capacitor entirely, the latch is ready.

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May 30, 2012 at 10:56 PM delete

Hi, I'm from Viet Nam.
Can you help me to to make some modifications to this circuit?
Instead of use a push button, we use a normal switch. When we turn on the switch, relay is active. After 5s, relay get off and we turn off the switch.
We can turn on/off the switch many time without affect to circuit.
I think it's very interesting for you, so I hope you will help me, please. Thanks very much!
My email: master_pro2510@yahoo.com
P/s: Sorry, I have English trauma! My language is realy terrible!

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May 31, 2012 at 6:25 PM delete

Hi Hoang,

I'll help you to make this circuit, in return you will also have to help me with a 300 word article.
Explain the above requirement in your own words to me, I'll publish it as a new article with your name and also the required circuit diagram.

You can correspond with me at hitman2008@live.in

Regards.

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Anonymous
June 16, 2012 at 8:10 PM delete

Nice and useful circuit. How much time will pass before capacitor is discharged if resistor is 2m2? How much time is needed for capacitor to fully charge? If I add 12V relay at place of LED would I need to change BC557 for a more powerful one? (it would be also helpful to leave LED as indicator of circuit working)

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June 17, 2012 at 8:13 PM delete

Thanks!
Actually the formula is little complicated and therefore I did not mention it here, it's better and easier to check the results through practical experimentation.

BC557 is OK for operating a relay.

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August 7, 2012 at 4:45 PM delete

Hello there,

Many thanks for that. This could solve me a big problem. I do require some more help - I hope it's not too much trouble.

1. I'm bound to a 1.5V DC power for various reasons. Would your circuit still work? If not, can you please suggest modifications so it does?

2. I require a delay of half a second roughly. What values of R / C should I use for that?

Kind regards,
josef.

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August 7, 2012 at 5:59 PM delete

Hello Josef,

Yes the circuit will work with 1.5v supply.

The first circuit will be OK, just reduce the base resistor of BC 547 to 1K. I am not sure about the capacitor which would produce 1/2 sec delay, you can try different values, start with a 0.1uF then either increase or decrease it, depending on the results.

I wonder how you would measure the 1/2 sec timing.

Regards.

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August 7, 2012 at 8:35 PM delete

Hello,

Thanks a lot for your prompt response - I will certainly give it a try.

I will not measure the 1/2 sec - I'm trying to start 5-6 clocks with a single switch but I want them not to tick at the same time but rather have "distributed" ticking sound. Therefore, for each clock I plan to add your circuit and change the capacitor (which from your answer I understand sets the time) so overall I will get a delay in the range of roughly 0.1-0.9 seconds (different for each clock).

You suggested 0.1uF for 0.5 second delay. If I want to play in the range of 0.1-0.9 seconds, do you have a rough estimate of what range of capacitors I should play with?

All the best,
Josef.

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Anonymous
August 8, 2012 at 6:36 AM delete

My situation might require a different type of circuit altogether, I need a timer that is going to turn a 12vdc fan on for about 3 minutes. Is this type of circuit practical for such a long period of time?

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August 8, 2012 at 7:37 AM delete

The capacitor and the 33K resistor shown in the figure, both together decide the timing delay period, either increasing the capacitor or the resistor value will result in an increase in the delay period.

Actually I don't know what value would produce a 1/2 sec delay, a 1K and 0.1uF will certainly not give you this delay, I just told it randomly.

I think with a 1K, you would require a 1uF cap, which would probably give delay in seconds range, you will have to adjust either the resistor or the capacitor value for achieving the exact timing. You will have to find it by trial and error.

Thanks and Regards

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August 8, 2012 at 7:43 AM delete

Please refer to the following article, this would fulfill your need, with little modifications:

http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-simple-timer-circuit-using.html

Regards.

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Bernie
September 5, 2012 at 7:00 PM delete

Hi. Very good article. I want to set up a time delay for turn on and practically no delay at turn-off to eliminate pops in the speakers. The system is running about 200watts of power. Will the above circuit with the one transistor work?? If so,do I need to use different value of components?? I want a 3 or 4 second turn on delay with no turn off delay.Any advice greatly appreciated....
Cheers,
Bernie

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September 5, 2012 at 10:04 PM delete

Hi,
This circuit will need to be changed significantly for the required application..it cannot be explained through words, I will have to draw it practically.
I'll possibly do it soon and present it here.

Regards.

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September 16, 2012 at 2:02 AM delete

Hi, this is an excellent article, thank you.

I would like to use such a circuit to effectively 'hold down' a key on an older mobile telephone (a Nokia 3310) so I would solder two wires onto the key terminals (let's say it is the '2' key) then have these two wires go to the delay circuit where I can hard-wire another button.

When this new button is pressed then the original button's circuit is closed for just over 1 second and this activates the phones speed dial for that number.

Would you be able to give any advice as to how I would do this without blowing up the phone :)

Also to be really clever it would be great if the pressing of this second hard-wired button actually energises the delay circuit so that it can sit there using zero power until use, then I could use the phone's battery to power it without the phone going flat all the time :)

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September 16, 2012 at 2:33 PM delete

Hi Ian,

Thanks, and welcome to my blog.

Yes it's very much possible without blowing anything.

You just have to connect two wires to the relevant cell phone key pads over the PCB of the cell phone very carefully using smd soldering iron.

The other ends of these wires may now be just connected with the relay's pole and the N/O contact, polarity does not matter.

The relay circuit will require an external 12V supply, it may be provided from a small battery.

The relay circuit consumes current only until the relay is switched, the moment relay is deenergized, the current consumption become almost zero. The relay cannot be operated using the cell phone battery unless it's some kind of a specialized mini low voltage type relay;)

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September 16, 2012 at 6:26 PM delete

Thank you Swagatam!

Do you think I might be able to use an optocoupler instead of a relay?

If so then perhaps I might be able to use the first, simpler circuit and maybe power it from the phone?

I agree that I will have to do some very careful soldering! :-/
Hope I can do that without destroying the phone :)

I'll keep you posted.

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September 17, 2012 at 12:07 PM delete

Hi Ian,

I don't think an opto coupler will work here, because a cell phone will require complete switching of its buttons for functioning, just as it is done through manual switching of the phone's mechanical keypads.
Opto couplers incorporate semiconductor switches which involve polarity, therefore it might pose problems.
So I think a relay would work better here.

Regards.

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Rick
September 25, 2012 at 10:02 PM delete

Hello

I think this is circuit I need for a project I am working on.
Can you tell me if it would work using a relay instead of a switch all using a 9v battery.

Thank you

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September 26, 2012 at 11:44 AM delete

Yes it will work only if the relay switches momentarily.

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Rick
September 26, 2012 at 11:25 PM delete

Thank you for the quick reply
Sorry I have one last question

The relay I am using is 5v so I will now be using 4.5v on the circuit, will I need to change the values of the components if so do you what to or how to work it out

Thank you for your help

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September 27, 2012 at 8:33 AM delete

I don't think any changes would be required, you may use the same circuit configuration with 4.5V also....

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October 16, 2012 at 2:42 PM delete

Hello! I need a circuit that will turn on an LED light 30 minutes after the switch/button is switched ON. can you explain this please?

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October 16, 2012 at 5:35 PM delete

Hi,

You can make the circuit shown in the following link:

http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-simple-versatile-timer.html

Just replace the buzzer with LEDs.

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Anonymous
October 25, 2012 at 4:49 PM delete

Dear
Can you make a timer which on for 5 or 10second and then off for 5second and then repeat again on for 5 or 10 second and so on continuously until power cut off.

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Anonymous
November 26, 2012 at 7:36 PM delete

Hi! Excellent article! I think your first diagram can make my project works, however, is it possible to create a circuit such that when a 12VDC is supplied to the + pole, the motor would turn clockwise after a 2 sec delay and when vise versa a 12VDC is supplied to the - pole, the motor would turn anticlockwise after a 2 sec delay? Very much appreciated

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November 26, 2012 at 8:14 PM delete

Thanks very much!

I am afraid the above circuit cannot be applied as per your suggestion. I think your application will require a set/reset kind of circuit. I'll try to figure it out.

Regards.

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Anonymous
November 27, 2012 at 2:53 PM delete

Gud afternoon sir, Excellent article...
But i need to use this timer with dark sensor. i.e. when lights off, then this timer get activated for few minutes (Without using Relay).
*Dark sensor is constructed based on 2NPN + LDR.
Could you please suggest me how to link with Dark sensor...?
Plz sir...
Thanks in Advance...

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Anonymous
November 27, 2012 at 6:51 PM delete

Very much appreciated! Thank you!

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November 27, 2012 at 7:50 PM delete

Thanks!

Alight sensor circuit is shown here:

http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-light-activated-day-night.html

The delay circuits supply terminals should be connected at the points where the relay is connected in the light sensor circuit, and the relay should be removed as it's not required.

In the delay circuit the switch should be replaced with a 0.22 capacitor and a resistor of 100K should be connected across the supply terminals.

The above mods should make the entire circuit work as per your requirements.

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November 28, 2012 at 4:14 PM delete

Thank you sir, Thanks you very much.
It is working with small modification.
Sir, can u give me any software name to design circuits like above (for PCB also).
Plz.....
Thanks in advance...

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November 28, 2012 at 5:18 PM delete

Thanks Vinay,

Actually I have never used any software for designing PCBs, so can't provide any useful info about them, you can probably Google a bit and you might find many of them online.

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November 28, 2012 at 7:51 PM delete

Sir, can u tell me how to flow limited current for mobile/something by using Resistors..
I need 200mA - 800mA current. So, can u say few words about current limiting (When u r free. I can wait sir)
Thanx in advance...

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November 29, 2012 at 11:49 AM delete

Hi Vinay,

Please tell me about the exact application that you are looking for, I'll try to explain you then.

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November 30, 2012 at 2:31 PM delete

Sir, i'm planning to recharge my mobile (Nokia) with my bike battery in both conditions (Bike Engine is ON & OFF).
By using 7805 IC, i'm unable to recharge my mobile,doesn't show any indication about charging. When using IC 7806, it shows "Charger not Supported".

Can u help me sir...? (I can wait for long time sir.Plz)

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November 30, 2012 at 2:40 PM delete

One more question sir.
When i'm using above 2Transistor circuit, It works fine in Breadboard, but on PCB, it's not working properly.I soldered components on PCB properly.I tried once again on bread board, it works. But on PCB it is not working properly.
I think, the quality of PCB is poor.I'm using MATRIXBOARD & connections are done by soldering copper wire.
NOTE: All connections on PCB are in correct(No doubt).
Can u give me suggestion sir...?

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November 30, 2012 at 5:56 PM delete

Use a different battery and check the result, or use an AC DC adapter and the 7805 circuit and check at home with mains voltage, confirm if the circuit is OK or not...

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November 30, 2012 at 6:13 PM delete

There may be some kind of short circuit or leakage between the leads of the transistors, or else there cannot be any other reason for it not to work, provided the connections are absolutely correct.

you may clean the PCB with thinner and check again...

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December 2, 2012 at 12:20 PM delete

Hi Sir Swagatam. This is really nice blog. May I please ask your help on my project. I want to have a time delaying circuit.

Desired setup:
After closing the circuit, the first LED light should switch on for few seconds then turns off. After few seconds, the second LED will turn on for few second then the switches off. The cycle DO not need to be repeated.

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December 2, 2012 at 9:36 PM delete

Thanks very much Marcos!

I'll try to update your request soon here, if I forget please do remind me....

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December 3, 2012 at 10:22 AM delete

Thanks Swagatam. This request comes from the Philippines. Actually, I've been searching this problem over the net for couple of month already but can't find anything specific. I even resorted to mechanical solutions already but not so much satisfied because I believe electronics is more efficient and effective and less bulky. Not until I came across with your blog. Though it is not yet exact as what Im longing to find but I have observed you're so accomodating and patient in answering queries as reflected in this long thread. Besides, this thread is active and updated. Im not so expert in electronics but an avid learner and trying to solve simple problems. Thanks so much. Im am so hopeful now and know now a site where to wait everyday. I will surely wait for your answer and be eager for it. Please take time and I wish to find answer now to my simple yet became serious desire.

Mabuhay ka kaibigan!

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December 3, 2012 at 11:52 AM delete

Thank you very much Marcos! I appreciate your kind words.

I've updated the required circuit, please check it.

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December 4, 2012 at 9:30 AM delete

Hi Swagatam,

Glad to see today your quick response to my query. Thanks so much for your time and effort. I will make this and share you the results after.

By the way, let me just clarify few things on the diagram:

1. Is the capacitor value read as 33uf 25V?(cant figure out clearly:)
2. The two vertical resistors (lowest in the diagram), are these 1K ohms too?
3. Can I use a regular 12V adaptor as source?

Thanks to your patience.

Best regards,

Marco Luis

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December 4, 2012 at 10:20 AM delete

Thanks Marco!

If you click the diagram, you would get an enlarged view of it.

Yes they are 33uF/25V, the LED resistors can be 1K 1/4 watt.

Any 12V DC supply can be used for this circuit.

Thanks and Regards.

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DMat
December 10, 2012 at 2:19 AM delete

Hi Swagatam,
Thanks for your time and energy for us non-professional electronics enthusiasts!

My circuit sounds an alarm if the refrigerator door has been left open too long. My microswitch attached to the door makes the circuit 'open' when door is closed, and closes the circuit, providing VDD, when the door is open.

Is there a version of your timer that will STOP counting in the event the refrigerator door is closed (VDD is removed from circuit) before the timer sets off the alarm? I assume most one-shot circuits involve charging a capacitor, in which case removing the VDD doesn't stop the timer....

Thanks
DM

Thanks

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December 10, 2012 at 9:57 AM delete

Hi DMat,

You are most welcome!

If the VDD is cut OFF everything immediately stops for the above circuits.

So you can definitely employ the circuit shown in the above article for your application, the second one is the most appropriate.

The alarm will never sound once the door is closed, because it will not be getting the supply voltage for generating the sound anyway.

Regards.

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December 10, 2012 at 9:59 AM delete

I am sorry the second circuit is not the one for your application, I'll update the article soon with an appropriate one.

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Anonymous
December 10, 2012 at 7:43 PM delete

how can I make this circuit to delay for 3-6 hours
? thanks
Ally From Tanzania

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December 10, 2012 at 9:35 PM delete

This circuit is not suitable for long duration applications, you may try the following circuit:

http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-simple-versatile-timer.html

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DMat
December 11, 2012 at 8:33 AM delete

Thanks a lot, Swagatam. I'll give it a go!

Regards,
DMAT

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December 11, 2012 at 11:54 AM delete

My pleasure!

I have made some changes in the circuit, please check it.

Regards.

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December 24, 2012 at 10:13 AM delete

Hi Swagatam,
Looks like you know your stuff when it comes to these timer circuits, this one is a little out there but dont believe it is out of your knowledge.
This is a replacement part for an old Bryant furnace 822 relay. What is needed is a circuit that will get a 24VAC supply when the thermostat kicks in, it will have to have a 45 second delay before triggering a relay that powers the 1/3HP blower motor, the motor needs to run for 45 seconds after the voltage is shut off via the thermostat. I'm sure that there is a more efficient circuit other than the 822 relay to do the job, especially when you take cost into the equation.

doug@evlllc.com

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December 24, 2012 at 8:13 PM delete

Thanks Doug,

So it should be like this in short:

thermostat kicks in ....>..... the timer starts counting and starts the motor after 45 seconds.....>....thermostat shuts off, but the timer keeps the motor ON for 45 seconds and then shuts it OFF.

The process repeats after the motor halts....right?

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December 25, 2012 at 1:33 PM delete

Thank you for the quick reply, yes you have it correct. Once the thermostat kicks in it sends 24VAC thru the limit switch(as long as it's not tripped from an overheat), then thru the pilot lights thermo coupler (providing that the pilot is lit)then applies it to the timer/relay. Once the thermostat kicks out the voltage goes to zero across all components.
Yes, the process would have to repeat each time the thermostat kicks the furnace on.
I was orginaly looking at the 556 timer chip to see if it would be able to serve the dual delay, but looking to you for the best way to get it done.

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December 25, 2012 at 8:11 PM delete

OK, I'll try to design the circuit soon, when it's done will post it here for you to see.

Regards.

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December 29, 2012 at 12:08 PM delete

Hi Doug,

I have tried to design the circuit correctly, please see it here:

http://homemadecircuitsandschematics.blogspot.in/2012/12/thermostat-delay-relay-timer-circuit.html

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Anonymous
January 3, 2013 at 4:22 PM delete

Hi Swagatam,

great job :)

I am looking for a circuit that turn off a LED after 20 minutes.
can you please help me, I am a biginer :)

thank you

mihai

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January 4, 2013 at 9:30 AM delete

Hi Mihai,

Thank You!

You can try the following circuit:

http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-simple-versatile-timer.html

Just replace the buzzer with a LED/1K series connection

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Anonymous
February 6, 2013 at 8:39 PM delete

Hi,

Please help me enhance any existing circuit that is using any timer or ic. It is for my project and our professor wanted us to add some functions to any of it.

Thanks,
Maye

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February 7, 2013 at 9:47 AM delete

you may try the following circuit:

http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-simple-versatile-timer.html

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Gavin
February 20, 2013 at 7:30 PM delete

Hello,

Looking at the 2nd picture, is there a way to get the delay up to 1.5 minutes? I've constructed the thing, but I can't seem to find a good combination of resistor/capacitor to get it up to 1.5 minutes delay.

Also, I assume that the effects are similar if used with a 9V instead of 12V battery? I'm currently running a 9V, since that is all I have access too.

Help would be greatly appreciated :) Thanks.

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February 20, 2013 at 8:48 PM delete

Hello,

You can try different values for the 2m2 resistor or the 1000uF cap.

Try replacing the 1000uF with a 10uF, it might produce closer results, then you can refine the outcome by tailoring the 2m2 resistor.

Yes 9V can be used here.

Regards.

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March 11, 2013 at 8:10 PM delete

Hello,

For my fridge door alarm project, I need an LED to turn on when the fridge door is opened and after a delay of 60-90s a buzzer would sound. Can I use any of the above circuits?

Regards,
Hakeem

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March 12, 2013 at 11:19 AM delete

hello,

the following circuit would be appropriate, with some further modifications though:



http://homemadecircuitsandschematics.blogspot.in/2012/01/how-to-make-simple-timer-circuit-using.html

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March 26, 2013 at 12:26 PM delete

Hi,

One of the requirements is that I can't use integrated circuits, but can I use the third circuit?

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May 18, 2013 at 9:52 PM delete

Hello. I am a glass specialist, pretty good with DIY etc, but not too hot on electrics. I am planning a build for a 10mm Toughened Glass Watch display box, however our client would like this to be a watch winder box. I have established that we require 4 x 10rpm 24V AC Motors to run simultaneously. They need to start turning every hour, for 15-20 minutes. However, they need to turn clockwise then anti clockwise hour to hour. It would be good if I could also have a manual option to start and stop the motors when I wanted.
Is this something someone can help with? Please? Thanks!Milton

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May 20, 2013 at 8:21 AM delete

Thank you for the request, I'll try to do it soon and publish it in my blog.

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Anonymous
May 28, 2013 at 8:13 PM delete

Hello, I am a broiler poultry farmer. I have no electronic knowledge or skills. I am looking to make some kind of relay, switch, vibration sensor that will alarm when the feed lines run for a certain amount of time which indicates that I am out of feed. This is causing damage to my equipment. I need something that will trigger a timer to restart every time the automatic feed line comes on. Basically I need something that will alarm if the feed line runs over 20 minutes. Could you post a schematic for something like this?

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May 29, 2013 at 1:27 PM delete

I'll try to post it in this blog...it might take a few days though....by the way how do the feed lines run, using DC motors or AC motors? because my circuit would need a trigger from it to begin the counting process so it's important to know regarding its voltage level..

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Anonymous
June 11, 2013 at 6:40 PM delete

how can i replace push button to simple ON/OFF switch.........
plzz help me out

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June 12, 2013 at 11:52 AM delete

what do you intend to make with this circuit?? the switch condition will depend on that.

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Anonymous
July 16, 2013 at 3:27 AM delete

I have constructed a simple 12 VDC circuit that includes a power supply and a linear actuator. The actuator has internal limit switches that open the circuit when it is fully extended or fully retracted. After one of the limit switches opens the circuit, the input polarity to the motor must be reversed to restart the motor to extend or retract. I need to modify the circuit so that when the 12 VDC power supply is energized the actuator will extend or retract, depending upon its position when the 12 VDC power was last de-energized. When a limit switch opens ( ie the actuator is fully extended or retracted), there needs to a time delay of 30 seconds to 3 minutes and then the polarity to the motor needs to be reversed to start the actuator. This process needs to be repeated without any manual input other than Initially energizing the 12 VDC power supply. Can this be accomplished with relays and timers or is a PLC the best method? Thanks for any advise you can offer.

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July 16, 2013 at 11:57 AM delete

I guess your need matches the one explained in the following article:

http://homemadecircuitsandschematics.blogspot.in/2013/06/programmable-bidirectional-motor-timer.html

Though it's quite complicated, probably it's the only way of doing it through discrete components.

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Anonymous
August 15, 2013 at 5:57 PM delete

hi there, can u help me to construct a timer circuit for me?
i use the timer to control the delay of the rotation of 3 stepper motors in sequence.
which means when the first motor move back and forth for 180 degree,it will delayed for 2 seconds before the second motor starts to rotate,the same process goes to the third motor.and i need the motor to completely stop and reset so that when i pushed the push button ,the first motor will repeat the step ..

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August 16, 2013 at 4:45 PM delete

The sequential timer can be surely designed, in fact I have already posted one such design in this blog, however I could not understand the connection between the motor rotation and the timing, if you could clarify that part then I could possibly suggest you an appropriate design.

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Anonymous
August 25, 2013 at 2:09 AM delete

Hi,

Can your make me a circuit using a tilt switch instead of a push to on, a 3-16v buzzer and a key switch that has a 10 second delay

Thanks a lot

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August 26, 2013 at 8:15 AM delete

Replace the push-switch in the second circuit with the tilt switch terminals with a series 1uF/25V capacitor.

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Anonymous
October 7, 2013 at 1:17 PM delete

Hi guys!
I need transistorized repeating timer, I need to have timer that will work without triggering switch but should work for two minutes and be off for two hours then after two hours repeat as first stage without pressing a switch again.
Please any one can help me.

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October 7, 2013 at 9:40 PM delete

I can provide a 4060 IC circuit, not a transistorized one.

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October 10, 2013 at 5:55 PM delete

Good day,
I have a 24vdc door activation circuit that I need a 5 second timer for. When the push paddles is depressed, I need to activate the latch relay for 3-5 seconds (to hold the latch open long enough for the operator to activate). Can one of your 12v circuits be modified to work with the 24vdc power supply?

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October 11, 2013 at 9:56 AM delete

Good day!
you can try the second circuit presented in the above article, replace the LED/resistor with the latch relay with protection diode.
The push button may be replaced with the paddle switch.

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October 11, 2013 at 9:57 AM delete

...the 1000uF cap should be tried with different values ranging from 10uF to 100uF for acquiring the required delay.

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Anonymous
October 17, 2013 at 5:57 PM delete

Good day, I think it can be done by replace NC and NO wiring on the relay.

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Anonymous
November 11, 2013 at 11:00 PM delete

Hi
I am after a circuit which will turn a 12 V light on with a switch and then will turn it off a fixed amount of time (about 5 seconds) after a tilt switch has been tilted. It is a project to help out my cousin and I can't get it to work and I would be really grateful if you could help.
Rich

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November 12, 2013 at 10:28 AM delete

The 12V light should illuminate and timing initiated when the tilt switch is tilted the first time or after its tilted back to its original position??? please clarify this point.

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December 7, 2013 at 6:33 PM delete

I want to create a small, variable delay. Changing the resister on the transistor base will allow the delay to be adjusted?
Using a 12v supply, can you recommend what resistance and capacitance values I should experiment with to induce a delay between 0.1 and 0.5 seconds?

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December 8, 2013 at 10:21 AM delete

you can try the second circuit given in the above article, use a 1M pot in series with a 1K resistor at the base of the transistor and a 10uF capacitor

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dbp
January 14, 2014 at 6:33 AM delete

Hey everyone,
I am looking for a time delay circuit that I can use for some drop photography. I am looking to conenct a light gate to it so that when a drop breaks the gate it starts the time delay circuit then triggers my flash gun. (flash gun has a 2 wire cable to connect to circuit). Does anyone know of a circuit which can help me? If you could include the light gate into the circuit would be a bonus.

Thanks :)

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January 25, 2014 at 4:05 PM delete

Swagatam... i need circuit, that after power on the circuit , output should be 5 or 10 sec, delay...Please help.

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January 27, 2014 at 9:15 AM delete

you can try this:

http://homemadecircuitsandschematics.blogspot.in/2013/02/make-this-simple-delay-on-circuit.html

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June 28, 2014 at 8:27 AM delete

Good morning sir,
I am totally confused with so many timer/delay ckts. Please refer me a ckt.
as per my requirements.
1) I want to start a 12v/500mA (max)
d.c gear motor after 40-60sec of switching on and will run untill it is switched off.
2) Another previously related problem.please refer any 12-0-12 a.c to 12v d.c rectifier ckt.with component
list and diagram......thanks.....
With regards,
K. Kausik

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June 29, 2014 at 9:05 AM delete

Good morning kaushik,

you can try the following circuit, the values of C2, R2, D1 will decide the length of the ON time delay.

http://homemadecircuitsandschematics.blogspot.in/2013/02/make-this-simple-delay-on-circuit.html

please repeat your previous request, I am not able to remember it.

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August 25, 2014 at 7:30 AM delete

hi can you suggest to me a simple circuit with 15 components for me as an electronics student ............pls i know u can help me...

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August 26, 2014 at 12:43 PM delete

hi, you can try the following design:

http://homemadecircuitsandschematics.blogspot.in/2012/04/semi-automatic-water-level.html

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September 1, 2014 at 8:31 AM delete

i want to make ten LED light using time delay feature having fed one by one after specific time day.

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September 4, 2014 at 11:48 AM delete

Hi Swagatam,
I wanted to make a timer circuit which cuts off the supply to a circuit after 5-6 seconds after being triggered , even when the trigger is still on

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September 5, 2014 at 11:40 AM delete

Hi Shyam,

you can try the following design:

http://3.bp.blogspot.com/-FHAn8wSZwQ0/UrFIJJpYjgI/AAAAAAAAF7I/M8L5IqLxCwA/s1600/automatic+choke+solenoid+circuit.png

ignore the relay contact capacitors and wiring set up, it was drawn for a different application.

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September 8, 2014 at 5:29 PM delete

Hi Swagatam,
I Tried the circuit which you gave , but the relay never turns off... I have changed the capacitor values ,but also no change.... can you please tell me what could be the problem.

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September 8, 2014 at 6:31 PM delete

Hi Shyam, I think I misread your requirement, the given circuit is good but is not applicable as per your need.

I'll give you a suitable one but let me know whether it should be a relay operated or without a relay, meaning the current requirement of the circuit is relatively higher or nominal??

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September 9, 2014 at 10:22 AM delete

Hi Swagatam, I wish to operate a 12v relay with this circuit. the current requirement is nominal.

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September 10, 2014 at 9:36 AM delete

Hi Shyam, I think the previous 555 based circuit which I recommended is perfect for your application and it'll surely work. Connect the relay between pin3 and ground, and make sure the line connecting pin4/8 of the IC gets the (+) 12V supply....remove the entire relay connections that's shown in the original diagram....your relay must be between pin3 and ground....let the 1N4007 diode be there with the coil, its anode will go to ground and cathode to pin3.

I thought that you wanted the entire circuit to get cut off after 5/6 sec but later realized that you wanted to execute the cut for another circuit via this timer circuit, therefore the suggested 555 circuit is right for the application.

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September 10, 2014 at 1:30 PM delete

Dear Sir ,it still doesn't work because, as I had mentioned earlier the switch remains on . Only when I turn off the switch the relay gets off immediately,there is no 5 sec delay even then.

Sorry Sir if I am bothering you too much..

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September 11, 2014 at 10:50 AM delete

Dear Shyam,

It seems there's something seriously wrong in the connections or the IC may be faulty, because the circuit is extremely standard and straightforward and should start working immediately.
pressing the push button should trigger the relay, and switch it off after the predetermined delay decided by the values of the 47K res and 10uF cap, irrespective of the switch position.

http://3.bp.blogspot.com/-FHAn8wSZwQ0/UrFIJJpYjgI/AAAAAAAAF7I/M8L5IqLxCwA/s1600/automatic+choke+solenoid+circuit.png

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Hex
September 14, 2014 at 1:01 AM delete

Hi Swagatam

Hoping you will be able to suggest a suitable circuit for a problem we are having. We need a circuit that can be fed via an engine ignition switch which will output a 12v feed to a solenoid for a short time, about a second, then power down once the feed from the ignition switch is turned off. Basically we have a piece of equipment that no longer turns off with the ignition switch, our current best option is to directly wire in a switch to the solenoid but if the circuit I describe is feasible then that would be a preferred option.
Thanks in advance.

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September 15, 2014 at 8:34 AM delete

Hi Hex,

There are a few confusions:

Do you want the solenoid to stay ON for 1 second after the ignition is turned OFF or should it be in response with the ignition switching, or is it regardless of the ignition ON time? Meaning once the ignition is switch ON, the solenoid will switch OFF after a second regardless of the ignition ON/OFF situation??

What kind of solenoid are you using, a spring loaded one or the one which requires a push-pull opposite supplies for locking and unlocking.

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November 29, 2014 at 9:37 AM delete

hello sir . i need a similar circuit but with 1 hour delay. What changes should i do?
Thankyou

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November 29, 2014 at 12:01 PM delete

Priyanka, you can try the following design:

http://homemadecircuitsandschematics.blogspot.in/2014/11/long-duration-timer-circuit-using.html

the 1000uF/2m2 components will need to selected by some trial and error for achieving the desired delay response.

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March 1, 2015 at 6:52 AM delete

how would i do a circuit like this that turn off 5 seconds after being turned on with a 12v source?

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March 2, 2015 at 7:59 AM delete

use the first circuit, connect the load or the circuit in place of the LED/resistor

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March 6, 2015 at 8:24 PM delete

Hi Swagatam

I have a circuit what is exactly like the one in "simple delay timer circuit". The only minor difference is +5V, and the major one is that it has to be approximately 1 sec "Delay ON" and immediately off again.

How would I do that?
Thank you

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March 7, 2015 at 11:32 AM delete

Hi Detlef,

In the first circuit, you can remove the 1000uF capacitor and replace the push switch points with a 100uF capacitor, now it'll behave in the way you have suggested, you may need to tweak the value of the 33k resistor in order to achieve the required 1 sec timing.

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March 8, 2015 at 11:56 AM delete

Hai, I need to place three LEDs L1, L2, L3 in a single circuit. So when I power ON the circuit means, the LED L1 should glow after 30 mins and the LED L2 should glow after 45 mins and the LED L3 should glow after 60 mins. Could u pls provide a circuit for that???

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March 9, 2015 at 9:06 AM delete

Hai, you can use a IC 555 and IC 4017 "chaser" circuit, set the 555 as a 15 minute timer astable and then use the outputs of the 4017 IC for getting the required sequences.

for 30 minutes you can just skip one output of the 4017.

make sure to connect pin15 with pin10 of the IC 4017

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March 9, 2015 at 1:28 PM delete

Thanx. I tried an 555 astable calculator to obtain 1 sec time high and 15 mins time low. But not able to obtain a correct value for R1, R2, C. Could u pls help me by giving the value for R1, R2 and C for the 555 astable circuit for 1 sec time high and 15 mins time low? Thanx...

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March 9, 2015 at 5:55 PM delete

15 minutes high, and 1 sec low will also do.

R1 = 1.3 Meg

R2 = 1.5K

C = 1000uF

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March 18, 2015 at 11:49 PM delete

Hi, Swagatam,

i need a delayed off timer working on 3v dc power supply , kindly share your idea if you have.

Best Regards,

Obaid

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March 19, 2015 at 1:53 PM delete

Hi Obaidullah, you can try the second or the third design from the above article

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March 31, 2015 at 2:23 PM delete

Dear Sir Please help me ....

I Want A Circuit Wich can Relay On 6v For 20 Second from get A Puch....


After 20 Second It Will Automatically Goes off

Again push then get on for 20 second

Thanx Sir

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April 1, 2015 at 9:45 AM delete

Dear Sharoj,

You can make the first circuit from the above article, just replace the LED assembly with your relay

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Anonymous
April 27, 2015 at 6:31 PM delete

Hello,
Do you know if it is possible to use instead a 12V supply a 9V supply?
Thanks

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April 28, 2015 at 1:28 PM delete

Hi, for the shown circuits you can use any voltage between 3V and 24V

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June 3, 2015 at 10:14 PM delete

Hi, i need a circuit that has 1 push to make switch but can control 2 things (in this case a water pump and fuel injector) i want the water pump to be going before the injector does its thing to build up enough pressure in the hose and all this needs to work on 12V. Can you help?

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June 4, 2015 at 12:33 PM delete

Hi you can use the second circuit from top and do the following modifications:

replace the LED/resistor with a relay coil (connect a diode across the coil).

Now connect the pole of the relay with the 12v positive, N/O with (+) of the water pump and the N/C with the (+) of the injector...the (-) wires of the two units may be joined together and connected with the circuit negative.

The above mods will allow you to implement the actions as specified by you.....reduce the 1000uF value for setting the required time delay between the pump and the injector activation.

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August 14, 2015 at 12:58 PM delete

hi there, i need a 15v circuit with a push-button that when i press and hold for 3 seconds then release the circuit LED will remain on for 10-15 seconds without dimming effects. Is it possible? Thanks for your help.

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August 14, 2015 at 1:00 PM delete This comment has been removed by the author.
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August 14, 2015 at 1:01 PM delete This comment has been removed by the author.
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August 14, 2015 at 5:55 PM delete

hi,

the first circuit in the above article will fulfill your requirement, but you won't need 3 seconds to initiate it, just a fraction of a second press will be enough to trigger the LED for the desired length of time...

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August 19, 2015 at 3:05 PM delete

hi mr swagatam,

is it possible i add one more LED to the circuit but it will delay on around 2seconds after the 1st LED light up and both LED will off at the same time.
Thanks for your help.

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August 20, 2015 at 3:47 PM delete

Hi Babusan,

I will have to figure it out, can't able to simulate it quickly...if it's possible I'll produce it in the above article soon...

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August 20, 2015 at 6:12 PM delete

hi swagatam,

sure, hope to hear from you soon. Thank you in advance.

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August 26, 2015 at 8:29 PM delete

Hi Swagatam,

I am impressed with the simple design you manage to came out to create a time delay without using the common 555 timer IC which most users would have used.

I am interested in the formulas on how did you manage to determine the values of the resistors and capacitors and I believe one does not simply just random pick the values and try it out to determine it. It would be great if you can provide me a rough explanation on the formulas part and also how does the circuitry works

For instance, in the section where you mentioned about adding an additional transistor to the circuit would increase the time delay but why and how does it affect the time delay? Does it have anything to do with the transistor switching on/off and meanwhile does it mean the more transistors the circuit has, the longer the delay it can provide?

Hope to hear from you soon. Thanks:)

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August 27, 2015 at 11:35 AM delete

Thanks John,

Definitely there should be a universal formula for determining the RC timing values, however determining the same using a practical trial and error method is much simpler than solving the formula.

If you are interested to know regarding the formulas, you can refer to the following wikipedia article:

https://en.wikipedia.org/wiki/RC_time_constant

By adding more transistors we are making the circuit more sensitive to the voltage rise across the charging capacitor...so if one transistor requires 0.6V to trigger, with two transistors we could reduce it to 0.3V with three transistors it can become more sensitive and trigger at 0.1V..this improvement allows smaller capacitors to be used and generate longer time delays...however making the circuit more sensitive can make it prone to false triggering from external spurious signals, that's the drawback, although this can be tackled by adding caps across the base/emitters of the transistors.

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September 1, 2015 at 1:02 AM delete

Hi,
I need a circuit which has two out on and off.
I mean one on and the other off and reverse with transistor or mosfet.

Thanks

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September 1, 2015 at 1:03 AM delete

Hi,
I need a circuit which has two out on and off.
I mean one on and the other off and reverse with transistor or mosfet.
So i can pulse it with 555.
Thanks

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September 1, 2015 at 9:09 AM delete

you can use a 4047 IC...a 555 will not be needed as it has it's own oscillator.

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September 2, 2015 at 9:47 PM delete

Hi Swagatam,

Thanks for the link and explaination on how the side effects it will cause for having more transistors and it really give me a better idea of how the circuit work out. Currently I have another quiry which is why when do you use a pnp transistor and connect in that format instead of using the NPN transistor and connect back the similar connection like in the first circuit?

Does it have any differences? (like lesser power consumption? neater? lesser voltage required?)

Hope to hear from you soon:)

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September 3, 2015 at 1:13 PM delete

Hi John, the PNP transistors activates in response to a negative (-) pulse at its base...the in the discussed design the NPN is supposed to produce a negative pulse when activated which is intended to be responded by the next stage, and therefore a PNP stage is used in that position.

together they make the circuit more sensitive than a single NPN

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September 6, 2015 at 12:24 AM delete

Hey, I need a circuit that can delay a signal output to a electric motor. I would be using a 9v battery to
power the circuit and a contact switch to turn it of and on. I need the motor to turn on about 0.5s after the contact switch is pressed and to stay on until the contact switch is no longer pressed.

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September 6, 2015 at 10:18 PM delete

you can use the following circuit:

http://www.homemade-circuits.com/2013/02/make-this-simple-delay-on-circuit.html

adjust C2/R2 appropriately for the intended delay period....you can eliminate the emitter zener diode D1, since it's required only for longer delays.

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September 11, 2015 at 1:27 AM delete

Hi!
I need a circuit with auto stop when the dc motor stops.

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September 13, 2015 at 5:00 PM delete

Thank you so much for the article! I am working on a analog circuit that controls the glowing time period of a bulb.
I'm using a relay,2 resistors and 2 capacitors,one is electrolytic and the other one is ceramic. I understood the role played by electrolytic capacitor i;e it stores enerygy but I'm unable to figure out why on earth is the other capacitor used for. PLEASE check the link for circuit

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September 16, 2015 at 12:07 PM delete

Hi Swagatam Majumdar

I find that circuit requested by Fastshack3 is useful to my case, well.... almost, since it require 12V signal to activate. Is there any way to activate the circuit with ground or 0V signal?. Thanks in advance

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September 16, 2015 at 7:08 PM delete

Hi balakutak,

you can do it by eliminating the BC547 stage and replacing the collector/emitter position with the push button and the capacitor.

the base resistor of the BC557 could require an increase to may be upto 100k

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October 12, 2015 at 8:00 AM delete

Hello. I am trying to build this circuit -
http://s768.photobucket.com/user/dpbayly1/media/BMW%20X5%20Folder%20%202/autofoldmirrors_zps53079bfd.png.html - but the problem is, the time delay relays that I am using, does not reset, when the SPDT relay changes its state from NO to NC, as mechanical switch of the central pin is too fast. Is there a way to "slow" down the flow of electricity, when the pin switches? I was thinking about two coils, one at pin 87A and the other at pin 87. what do you think?

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October 12, 2015 at 11:16 AM delete

you can reduce the current to the relay coils for reducing the electromagnetic pull, but still that would create a difference in milliseconds only....

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October 12, 2015 at 6:44 PM delete

Good day

i would like a circuit that counts up in hours maybe to a maximum of 5 hours continuously when every time it is switched ON.i have been having a problem with this for a long time now.

Thank you

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October 13, 2015 at 8:29 AM delete

you can use a 4060 and 4017 timer circuit as given here:

http://www.homemade-circuits.com/2012/04/how-to-make-long-duration-timer-circuit.html

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November 28, 2015 at 9:26 AM delete

Is is possible to make a circuit that lights up a bulb but then a momentary switch can cut the power to turn the led light off? The tough part would be to keep the light off for longer than when you release the switch. I want the bulb to stay off for 5 seconds before it getting power again.

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November 29, 2015 at 9:25 PM delete

you can use the second circuit from the above article, and replace the BC557 with another BC547 transistor..after this you can tweak values of the 1000uF and the 2M2 for getting the desired off time delay

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January 25, 2016 at 2:52 AM delete

Hi, good job on these. Extremely useful, so thanks! Is it possible that when switch is pressed it only charges the capacitor but does not power on the light? The LED is only required on for 5 seconds after the switch is released.

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January 25, 2016 at 6:56 PM delete

you can try connecting a 220uF capacitor in series with the LED with a 1M resistor in parallel with this capacitor, this will probably take care of the mentioned situation.

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