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Choosing an IC

Discussion in 'Electronic Basics' started by Pete, Jan 3, 2006.

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  1. Pete

    Pete Guest

    Hey Everyone,

    First of all, thanks for reading this. I'm a beginner at electronics so
    you know.

    I'm looking for an IC to use in a particular project. I'm designing a
    four-barrel automatic paintball-gun turret. I've succeeded in making a
    two-barrel version already. It took me three revisions. Anyways,

    I'm looking for a quad AND gate IC. It must trigger on the leading edge
    of a 5v HIGH signal. Preferably something CMOS, nice and durable. You
    don't want your gun turret to die in the middle of a fire fight.

    (you can skip the next paragraph.. unless you're interested)

    The device drives solonoids, which physically pull the firing pins in
    the guns. A 555 timer pulses at 40Hz, and a 4017 decade counter divides
    the timing signal into four lines. However, the output from the 4017
    can't go straight to the solonoids; the duty cycle is too long. If the
    firing pin is not returned immediately, the gun will not be able to
    re-cock itself. So using four AND gates, the 4017 can be filtered by
    the 555 output, making it so that each channel has a short duty cycle
    as determined by the 555. This allows the solonoids to pop down and
    return up very quickly, before the next solonoid fires.

    In my first model, which fired two guns in automatic succession of
    eachother, I used PNP transistors as AND gates. These were leaky, and
    caused random gunfire. Plus, their overall implementation consumed
    space and allowed for more error. I want to replace them with an IC
    package specifically designed as an AND gate, that runs on 5 volts, and
    maybe has schmitt triggers. So if anybody has any suggestions on which
    IC to use, your advice would be appreciated.

    You can skip the next paragraph too.

    The leakiness issue probably raises a few of your eyebrows. It sure
    raised mine. I never really narrowed down the cause to anything in
    specific. Might have been caused by induction current from the
    solonoids, which consume 4 amps, and probably create massive induction
    spikes. These are defeated by high voltage diodes, but perhaps the
    current is looping through and causing the solonoid to double-fire. Or
    leaking through a film of flux on the PCB and triggering the power
    amp's base pin. I better implement a discharge lamp to kill that
    induction spike. Oh well. I'll do all that later. For now I need to
    eliminate all other possibilities.. like the homemade AND gates.

    Thanks everyone for your time.
     
  2. I know of no AND gates that also include Schmidt triggers. There are
    NAND gates (MM74HC132, CD4093BC), but you would have to add an
    inverter like a section (or several in parallel for more output
    current) of a MM74HC04, CD4069UBC, CD4049, MM74HCU04.

    http://www.fairchildsemi.com/ds/CD/CD4093BC.pdf
    http://www.fairchildsemi.com/ds/MM/MM74HC132.pdf
    http://www.fairchildsemi.com/ds/MM/MM74HC04.pdf
    http://www.fairchildsemi.com/ds/CD/CD4069UBC.pdf
    http://www.fairchildsemi.com/ds/CD/CD4049UBC.pdf
    http://www.fairchildsemi.com/ds/MM/MM74HCU04.pdf
     
  3. Pete

    Pete Guest

    Thanks John!
     
  4. Pooh Bear

    Pooh Bear Guest

    Gates don't 'trigger'.

    What do you really want ?

    Graham
     
  5. Pete

    Pete Guest

    Gates don't 'trigger'.

    I guess you're right Graham, thanks for correcting me.
     
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