Readers are advised to proceed with the construction of the presented circuits only after understanding the concepts from the core. Not adhering to this can lead to failures and frustrations.

Search This Blog

Loading...

Tuesday, May 1, 2012

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!"


93 comments:

  1. 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

    ReplyDelete
    Replies
    1. 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.

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

      Delete
  2. success, adjusted some resistors too. thank you very much

    ReplyDelete
  3. 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.

    ReplyDelete
    Replies
    1. 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.

      Delete
    2. 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!

      Delete
    3. 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.

      Delete
  4. 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)

    ReplyDelete
    Replies
    1. 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.

      Delete
  5. 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.

    ReplyDelete
    Replies
    1. 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.

      Delete
    2. 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.

      Delete
    3. 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

      Delete
    4. 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.

      Delete
  6. 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?

    ReplyDelete
    Replies
    1. 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.

      Delete
  7. 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

    ReplyDelete
    Replies
    1. 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.

      Delete
  8. 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 :)

    ReplyDelete
    Replies
    1. 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;)

      Delete
  9. 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.

    ReplyDelete
    Replies
    1. 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.

      Delete
  10. 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

    ReplyDelete
    Replies
    1. Yes it will work only if the relay switches momentarily.

      Delete
    2. 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

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

      Delete
  11. 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?

    ReplyDelete
    Replies
    1. 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.

      Delete
  12. 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

    ReplyDelete
    Replies
    1. 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.

      Delete
    2. Very much appreciated! Thank you!

      Delete
  13. 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...

    ReplyDelete
    Replies
    1. 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.

      Delete
    2. 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...

      Delete
    3. 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.

      Delete
    4. 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...

      Delete
    5. Hi Vinay,

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

      Delete
    6. 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)

      Delete
    7. 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...?

      Delete
    8. 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...

      Delete
    9. 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...

      Delete
  14. 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.

    ReplyDelete
    Replies
    1. Thanks very much Marcos!

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

      Delete
    2. 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!

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

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

      Delete
  15. 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

    ReplyDelete
    Replies
    1. 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.

      Delete
  16. 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

    ReplyDelete
    Replies
    1. 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.

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

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

      Regards,
      DMAT

      Delete
    4. My pleasure!

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

      Regards.

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

    ReplyDelete
    Replies
    1. 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

      Delete
  18. 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

    ReplyDelete
    Replies
    1. 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?

      Delete
    2. 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.

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

      Regards.

      Delete
    4. 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

      Delete
  19. 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

    ReplyDelete
    Replies
    1. 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

      Delete
  20. 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

    ReplyDelete
    Replies
    1. you may try the following circuit:

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

      Delete
  21. 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.

    ReplyDelete
    Replies
    1. 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.

      Delete
  22. 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

    ReplyDelete
    Replies
    1. 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

      Delete
    2. Hi,

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

      Delete
  23. 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

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

      Delete
  24. 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?

    ReplyDelete
    Replies
    1. 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..

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

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

      Delete
  26. 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.

    ReplyDelete
    Replies
    1. 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.

      Delete
  27. 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 ..

    ReplyDelete
    Replies
    1. 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.

      Delete
  28. 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

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

      Delete
  29. 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.

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

      Delete
  30. 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?

    ReplyDelete
    Replies
    1. 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.

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

      Delete
  31. 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

    ReplyDelete
    Replies
    1. 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.

      Delete
  32. 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?

    ReplyDelete
    Replies
    1. 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

      Delete
  33. 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 :)

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

    ReplyDelete
    Replies
    1. you can try this:

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

      Delete

Readers are requested not to include external links while commenting. For consulting a diagram, upload it on Google Drive and provide the link here.