Bistable 555

Discussion in 'The Projects Forum' started by Wendy, Feb 27, 2010.

  1. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    Helping someone with another thread I think I've figured how to turn a single 555 into a flip flop. Check it out...

    [​IMG]

    This will end up in my 555 projects collection if it works. Confidence is high that it will.
     
  2. hgmjr

    Moderator

    Jan 28, 2005
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    Bill,

    Can you shed more light on how this circuit will be used?

    hgmjr
     
  3. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    The original was for an LED flashlight, and used 2 555's in a traditional manner to make the flip flop.

    The thread at this site wants to make a foot switch for a fog lamp.

    The only real claim to fame this design has is it has eliminated the extra inverter, and still has a nicely low parts count.
     
  4. hgmjr

    Moderator

    Jan 28, 2005
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    Bill,

    What you are aiming at is to provide a circuit that permits a momentary-switch to act like an alternate-action switch.

    The circuit you have posted would appear to do just that.

    The related post is this one. I think.

    hgmjr
     
  5. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    That's the one.

    AudioGuru has a schematic he posts using transistors. It think this beats it in simplicity.

    It is also a decent demonstration in how to make a flip flop flop.
     
  6. Audioguru

    Expert

    Dec 20, 2007
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    My circuit uses Cmos inverters so its supply current is almost nothing. It can drive a transistor or a Mosfet to turn things on and off using hardly any current when off.

    A 555 draws 3mA to 15mA all the time. A Cmos 555 draws 50uA to 400uA all the time.
     
  7. Wendy

    Thread Starter Moderator

    Mar 24, 2008
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    I consider my parade rained on.

    However, I'm still gonna post it! :p
     
  8. hgmjr

    Moderator

    Jan 28, 2005
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    It is yet another in the ever growing list of uses that you have found for the ubiquitous 555.

    hgmjr
     
  9. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Last edited: Mar 9, 2010
  10. retched

    AAC Fanatic!

    Dec 5, 2009
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    (Twenty years ago, yesterday)

    Bill, you are on a mission from god. This mission is to find all practical and impractical uses for the readily available IC known to the world as the 555. Get started.
     
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