Need circuit for multiple flashes, then turn-off

Discussion in 'General Electronics Chat' started by GreyBoy, Jan 22, 2008.

  1. GreyBoy

    Thread Starter New Member

    Jan 19, 2008
    2
    0
    I'm looking for a circuit that, when triggered by a push-button, will flash a couple of bright leds several times, say 5 to 10 times, then turns off by itself.

    I suspect it would utilize a 555 or an LM317T. Power by 2 AAs would be ideal. Can anyone help?


    Thanks all!
    Roger :D
     
  2. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    You should be able to pull this off with an LM556. This is a dual 555 timer. Of course you could use two LM555 timers just as easily.

    You could use one of the 555 timers in a mono-stable mode to enable the second 555 that would be operating in the astable mode. The first 555 would turn the second 555 timer on long enough to allow the second 555 to pulse the leds connected to its output 5 to 10 times. Then the first timer would time out and turn the second 555 timer off until the next time you pressed the switch.

    You may need to use 3 or 4 AA batteries to really have a bit of reserve power.

    hgmjr
     
  3. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,575
    230
    The attached circuit has not been tested...though various parts have worked separately.

    The circuit around U1 is a pulser that I used in a blinking third-brake-light. It pulses at a rate set by R8/R9 and C2. The pulses last for a for a period set by R5/R6 and C1. The output section R11 and Q3 should handle the LEDs...but I don't know what current you are driving the at. The push-to-start & auto turn-off section R1-R4 and Q1/Q2 is from a posting on the Parallax Basic Stamp Forum by Beau Schwabe:

    http://forums.parallax.com/forums/attach.aspx?a=3889

    Again, I have not bench tested the two together...but it might be worth a try.

    Ken
     
  4. GreyBoy

    Thread Starter New Member

    Jan 19, 2008
    2
    0
    Wow, thank you for the help guys. I'll try to decipher these schematics. I'm not familiar with what "Vin" "Stamp" mean on the Power Standby Circuit.

    I'm hoping two AA cells can blink big l.e.d.s.

    Roger
     
  5. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,575
    230
    Roger

    Vin is the + battery connection.

    Stamp ("Basic Stamp") is a micro-controller that Beau was using with his power Push-on/Program-off circuit.

    2 AA batteries?...depends on what LEDs you are planning on using. Red, green, or yellow maybe, but white...no.

    I'm not sure my circuit would work at 3 volts.

    Ken
     
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