Timer Relay Question.

Discussion in 'The Projects Forum' started by AaronG, Aug 10, 2009.

  1. AaronG

    Thread Starter New Member

    Aug 10, 2009
    6
    0
    Alright, I am working on a project and I have a question. This project will need to have a delay (5-10 sec) after the make. Although, I need it to turn off right after activation, with a very short (about a half second) period that it is on. Is this possible, and what kind of relay should I use?

    If you need to know, it will have to be able to support 16 Super-Bright Led lights. I do not yet know the power supply necessary, yet.

    -AaronG
     
    Last edited: Aug 10, 2009
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Can you make clear the desired operation of the circuit?
     
  3. AaronG

    Thread Starter New Member

    Aug 10, 2009
    6
    0
    The circuit is to turn on 16 different LEDs at once, then turn them off after ~0.5 sec.
     
  4. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    what input are you giving to enable the output? How long is that pulse? Is it a HiGH or LOW? and once when you get that signal, how long should it wait to enable the LED's? It is not clear from your request.
     
  5. AaronG

    Thread Starter New Member

    Aug 10, 2009
    6
    0
    I apoligize for not being clear. Unfortunately I am a beginner when it comes to circuits and have a fairly limited knowledge of what your asking. I do, however, know that I would want about a seven second delay for activation of LEDs. For the other questions, Im not really sure how to answer because I have no idea what you mean.


    Im sorry that im a noob.
     
  6. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    After the 7 secs delay the Leds will stay on forever?
     
  7. AaronG

    Thread Starter New Member

    Aug 10, 2009
    6
    0
    No, they should turn off after a VERY short period of time. So that the LEDS make a flash.
     
  8. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    Hey, everyone starts as a newbie. Noone is a born expert. So dont worry about that.

    And about the rest questions I asked, sorry if you didnt understand, but I got my answers. So you give a signal to the LED's, and they wait for 7 seconds and then blink and turn off?? Should they repeat that again and again or only once for each time you give the signal? One more question, the signal you are giving for that output, is it like a flip to on switch or just a push button like one??
     
  9. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    what are you trying to make?
     
  10. AaronG

    Thread Starter New Member

    Aug 10, 2009
    6
    0
    It should NOT cycle, it should only blink once. The project I am working on is hard to explain, but the switch would not actually be a button or switch. It would be two pieces of metal touching, so think of it working as a toggle switch.
     
  11. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    So the metal contacts will stay touched for a longer time interval than the timer will count?
     
  12. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    A non cycling circuit is more complex than a cycling one, thats why I asked. Let me see abt it.
     
  13. AaronG

    Thread Starter New Member

    Aug 10, 2009
    6
    0
    If by that you mean, when the contacts touch the timer will start counting, then after the delay the LEDs blink. After the blink the contacts are STILL touching.
     
  14. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    397
    Two 555's or one 556, first gives 7-10 sec delay, second gives .5 sec. driving unknown load. May need driver if load is more than 200 mA.
     
  15. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    397
    Next try.Two 555's , one for delay, second for pulse.
     
  16. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    Lots of people ask for a circuit to generate a pulse after a delay. I only know of using 2 555's, but isn't there any easier way to generate that 0.5sec pulse other than a 555??
     
  17. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    397
    jj, I've looked also. Trailing edge can be difrentiated and used directly for a neg going clock input or fed into schmitt trigger for a few msec + pulse.
     
  18. jj_alukkas

    Well-Known Member

    Jan 8, 2009
    751
    5
    I've learned in college of using a schmitt trigger, guess that could be done with a diode and cap right?
     
  19. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    397
    With diode and cap might make a pulse stretcher, but for schmitt, would use 555 or74C14, 74C914, or 40106.
     
Loading...