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Delay Relay

Discussion in 'General Electronics Discussion' started by Calmore, Aug 10, 2018.

  1. Calmore

    Calmore

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    Jan 19, 2015
    Hi All,

    I have an output from a device which is high, then goes low. I need to add a delay to this output such that it stays high for a further 30s, then operates a relay.

    Now, I need this to be replicated across a number of machines by relatively unskilled people, so building individual circuits for each one is out of the question. I'd therefore like to use COTS parts, if possible which can just be wired up using a wiring diagram. I can't modify the existing machine, either.

    There are a number of relay boards on eBay and elsewhere which offer delay functions, but to be honest I'm having difficulty working out the details of what they do! Descriptions are vague or in Chinglish..

    So, has anyone had any experience of such modules and can recommend one? It needs an input which when taken low, waits around 30s before closing the relay contacts. If the input goes high again within the 30s then the relay contacts need to remain open; low again and the 30s delay cycle starts again.

    Anyone know of anything suitable?

    Thanks!
     
    ratstar likes this.
  2. darren adcock

    darren adcock

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    Sep 26, 2016
    HI Calmore, can you give us a bit more information on what both the device is and if you can tell us what you are seeing on it's output?

    I'm probably not the person who can help you here, but I'm guessing the people who are best to help you will need this information

    Cheers
     
    davenn likes this.
  3. sumeryamaner

    sumeryamaner

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    May 29, 2017
    I have designed and built a similar device for a fishing boat. It was a module which controls a water pumup via a relay. The pump is being switched on for 10 seconds in intervals of some minutes. These intervals can be set using a potentiometer. I have used an Attiny85 microcontroller for this project.

    In your case your task can be accomplished by using a similar device but I do not know about ready built devices. If you want to build your device I can help you for the circuit design and code.
     
  4. AnalogKid

    AnalogKid

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    Jun 10, 2015
    1. What is the control signal voltage: 5 V, 24 V, AC, DC, etc.

    2. What are the characteristics of the relay being controlled: coil voltage, current, watts, manufacturer, part number, etc?

    ak
     
  5. WHONOES

    WHONOES

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    May 20, 2017
    I you can't find anything on the market that is ready made, a very simple device can be made that does not need a PIC or a processor of any kind. The 4538 precision monostable will work and needs just 2 timing components and is triggerable with either a positive or negative pulse and provide delays easily within the range you quote and can simply be made variable.
     
  6. Bluejets

    Bluejets

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    Oct 5, 2014
    So the machine or whatever this international secret device is, is currently shutting down perhaps by a stop button.
    Now you require this ( for example) stop button to be pressed but the machine to continue running for an added 30 seconds or an adjustable amount.
    A microcontroller instantly comes to mind but the mod may create other headaches such as how to arrange for any emergency shut down, which must be hard wired for safety.
    More detail on the machine and reasons why this mod is required I'd say would be essential.
    Many times there are alternative/ better ideas.
    As a side note, I would not be too hard on the Chinese given your requirement is invasive but you require a non- invasive add-on.
    Plus it seems it may be a specialised or custom mod but you want it to be done by untrained non- specialised people.
     
  7. WHONOES

    WHONOES

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    May 20, 2017
    A microcontroller is definitely overkill.
     
  8. Bluejets

    Bluejets

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    Oct 5, 2014
    I don't see why.
    Simple, cheap and if design changes, mods can be done in a flash( so to speak)
     
  9. WHONOES

    WHONOES

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    May 20, 2017
    So can an analogue solution with no code to develop and just a few components.
     
  10. Peter Taylor

    Peter Taylor

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    Jan 14, 2018
    :oops::oops:I wouldn't say a microcontroller is overkill. I order about 10 PIC 18F4455's at a time, because I use them for everything. A 30 S delay using an analogue capacitor type delay would be unreliable. A PIC would be perfect in a critical application.:eek:o_O:confused:;):(:D:eek::po_O;):):confused::cool::p:D:(;)
     
    Last edited by a moderator: Aug 11, 2018
  11. WHONOES

    WHONOES

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    May 20, 2017
    Not at all unreliable. Spose you have nothing better to do than stick lots of emojis on your replies.
     
    Last edited by a moderator: Aug 11, 2018
  12. WHONOES

    WHONOES

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    May 20, 2017
  13. imcooljoshi

    imcooljoshi

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    Aug 12, 2018
     
  14. imcooljoshi

    imcooljoshi

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    Aug 12, 2018
    relay is a automatic switch and we can control this switch by our requirement. relay are different operating voltage like 5v dc, 220v ac, 24v dc, 12v dc etc know more about relay click here in hindi language.
     
  15. sumeryamaner

    sumeryamaner

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    May 29, 2017
  16. WHONOES

    WHONOES

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    May 20, 2017
    I don't see the point in reaching for a ╬╝controller for such a simple task.
    I don't mind the odd smilie but that post was a bit excessive.
     
    ratstar likes this.
  17. ratstar

    ratstar

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    Aug 20, 2018
    If you have a long enough wire, put an amplifier at the end of it, and youll get a delay at how long it takes electricity to reach the other end. youd probably have to sit in a drum next to your machine tho, 30secs is a fairly long delay. :)
     
  18. AnalogKid

    AnalogKid

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    Jun 10, 2015
    I think the OP is gone.

    Don't discount long wires as delay elements...

    Broadcast quality video recorders of the 60's-70's used a pulse-integrating FM demod. Older RCA machines had a coil of coax cable strapped down in the middle of the demod pc board. The reflection from the unterminated end made a perfect monostable pulse that had almost zero drift with temperature. This was a creative way of compensating for not being able to design an all solid state monostable circuit that worked.

    ak
     
  19. BobK

    BobK

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    Jan 5, 2010
    Unless the delay is 30 seconds, as in this case.

    Bob
     
  20. Peter Taylor

    Peter Taylor

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    Jan 14, 2018
    Have I been overdoing the emojis again. I must have been drunk lol :) !!
     
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