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    The 555 adjustable timer circuit starts timing when switched on. The green LED lights to show that timing is in progress. When the time period is over the green LED turns OFF, the red LED turns ON and the beeper sounds. The time period is set by adjusting the variable resistor. It can be adjusted from 1 to 10 minutes (approximately) with the parts shown in the diagram. You can mark the times on a scale drawn on the box.

    Please note that the range of time periods is only approximate. With perfect components the maximum time period should be 4½ minutes, but this is typically extended to about 10 minutes because the 220µF timing capacitor slowly leaks charge. This is a problem with all electrolytic capacitors, but some leak more than others. In addition the actual value of electrolytic capacitors can vary by as much as ±30% of their rated value.

    Adjustable 10 minutes timer schematic

    adjustable timer schematic

    Source: http://www.kpsec.freeuk.com/projects/timer.htm


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    35 Responses to "Adjustable Timer Circuit with 555 IC"

    1. Sir, is this circuit is it 470 Ohms or K?

    2. Sir,I made this circuit on bread board as well as on PCB but its not giving expected output. Problem is that the red LED is continuous on.I think there is problem with trigger.can you please explain how trigger is created here.Please reply as early as possible.

    3. i agree with nalini
      i also faced the same problem……….

    4. Hi, the connections to pin 2 and pins 6,7 are the wrong way around. Connect the 1M pot the 100k resistor and the 220uf capacitor to pin 2, connect the 33k resistor and the 0.1uf capacitor to pins 6 and 7.

    5. My parents had the “old style” door chimes that are no longer available. I would like to try making a 3 or 4 chime set the has a one second delay to each striker. Can anyone help?

    6. Not sure what this point means:we started rensiignedg the timer; a task hover with mostly needed functionality is there;But to be honest the new timer design is a little annoying. The hover makes the tasks jump under the mouse and when you click on the task it no longer appears in the current task’ space which was handy. Could we have that back?

    7. This is so awesome! Just built this at work today. Works great.

    8. This circuit can be used as delay ON or delay OFF (TDR)

    9. thank you. How to the capasitor discharg?

      • Jim Keith says: on October 22, 2014 at 4:02 am

        Excellent question!
        C1 discharges into the 555 internal resistance when the switch is opened. The discharge may be slow –to speed it up, add a fixed resistor from the load side of the switch to common, and a diode across the 1M pot & 100K resistors (cathode up).

    10. Hi, I’m a engineer at British airways and we was working on something and saw this circuit, who ever made this circuit email me to claim your reward before use.

      Thank you

    11. Great simple, little circuit which has many uses.

      What size discharge resistor should i use assuming
      the circuit is switched off once week.
      I’m using as “delay on”
      Thanks for sharing!

    12. where is the pin 5 attached? if i will add FET and transistor where would it be attached?? please

    13. my green led the only that turned on once the switch is on, what happened?

    14. how about a time with 100nano sec.???

    15. how a timer works on both ac and dc? how its operate, circuit explanation briefly please?

    16. What adjustment would have to be made to this circuit to make it run from 24v dc?

    17. Electronic is never a destination but a journey, @ Davetech

    18. I want on delay timar sir please simpal curcut digram

    19. Will it work on 5vdc even?

    20. hi am kibugujju john from nile vocational institute uganda thank you for your ccts because they really work for me and adjusted my minds from childish electronics

    21. How hard could it be to update the picture here ? How many people will make this circuit and THEN read your fixes.. Try to update your web pages for this kind of critical data… :-(

    22. Can I use 555 timer for timing up to 20mins

    23. Where is pin 5

    24. Pin 5 generally connects to a 0.01 to 0.1uf bypass capacitor, but is often eliminated to reduce parts count. This capacitor can improve stability under some conditions.

    25. I need to press a switch that will trigger a relay for an adjustable output time (from ~0.1 sec to ~1 sec), to control a spot welder device. Can someone please suggest a circuit or modification of the one shown on this page?

    26. Hi How are you
      Sir
      Please tell me how can I make the 24 volt low battery disconnect circate

    27. Is there any timer to switch off the boar starter after 10 minutes

    28. I am trying to make this circuit to control a relay, which will power heated mirrors in my car. Environment: 12-14.8 volts DC, momentary switch, circuit controls a relay feeding DC current to mirrors for 1-10 minutes adjustable. How would I go about this? What parts would I need? I would like to keep a LED illuminated only while the circuit powers the relay, no need for a buzzer. Thank you. I am great with electronics, but not so great at creating them from scratch. :(

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