Keep the turn signal on

Discussion in 'General Electronics Chat' started by skinner927, Jan 12, 2009.

  1. skinner927

    Thread Starter Active Member

    Dec 31, 2007
    36
    0
    So I'm re-designing my tail lights and I need a constant trigger. Obviously I only get a pulse but is there something I can use to basically get the trigger, keep it for a second and if the trigger hasn't been hit in that second, turn it off, otherwise keep it on.

    I know how to do it with a micocontroller but I'd like to keep the cost down as I'll have to do this a couple times.

    I've searched here and online, can't find anything.


    It'd be cool if I could use a monostable 555 and every trigger would cause a reset and it'd send a signal again for a second since the trigger.

    W/e I figure someone on here would know :D

    Thanks
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Your explanation is a bit confusing. Explain better what you want to do.
     
  3. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    Use the 555 as an astable. Ground the reset (pin 4) when you want it off and hold the reset high (more than +0.7V) when you want it to run.
     
  4. skinner927

    Thread Starter Active Member

    Dec 31, 2007
    36
    0
    Easy explanation:

    I have an input that pulses at let's say ~1Hz

    I need to convert that to a constant HIGH.

    So I need to figure out how to make a circuit that will stay HIGH while being fed a 1Hz signal. So something that can take a trigger and stay HIGH for two seconds but if it's input DOES NOT go HIGH within those two seconds, the counter will turn off. But if at any time the input goes HIGH it will reset the clock to count for another two seconds.

    This is for my turn signals, I need to run a circuit off of the flash, but since it flashes I'll only get power half the time.

    The signal is not always a constant 1Hz either, it varies so I say keep listening for the signal for two seconds before going LOW. I really hope this make sense.

    Thanks again.
     
    Last edited: Jan 12, 2009
  5. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    The easiest thing would be to use the turn signal's input control instead of the turn signal's output. From the turn signal switch, I mean.

    Failing that, try a 555 monostable with output pulse very slightly longer than your signal period. Your gizmo will turn off within one cycle of the signal being turned off.
     
  6. skinner927

    Thread Starter Active Member

    Dec 31, 2007
    36
    0
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