push on push off

Discussion in 'The Projects Forum' started by badbaud, Apr 3, 2010.

  1. badbaud

    Thread Starter Member

    Mar 5, 2009
    26
    0
    Got this very tiny circuit going on the back of a business card. Runs off of a 3V button cell. How can I make the power applied to the circuit turn on and off with one tactical switch push? One push turns the circuit on and the next push turns it off. Is there some kind of one part solution to this problem?
     
  2. nofiller

    New Member

    Mar 30, 2010
    6
    0
    I think what you're looking for is called a flip-flop. You can get ICs that do that, but I'm not sure how small they would be...

    Start with CMOS 4013. http://www.doctronics.co.uk/4013.htm
     
  3. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    We need a bit more information. What are you going to do with this push on / push off? It so happens I came across a 555 circuit that does something similar. There are a lot of designs out there using different methods, the end effect is what is important.
     
  4. badbaud

    Thread Starter Member

    Mar 5, 2009
    26
    0
    The main IC has a on/off pin. Low is on and 3V is off. I wonder if there is a thin tactical switch that has "push on, push off" capability? Otherwise I will have to use a 555 circuit to turn the main IC on and off and a form "A" tactical switch. Damn, another IC added to the circuit, maybe a tiny slide switch would be better. It would prevent that "butt dialing syndrome" I hear so much about.
     
  5. Wendy

    Moderator

    Mar 24, 2008
    20,764
    2,534
    [​IMG]

    Never built this, but I think it will work. If you use a CMOS 555 you can go to 2V on the power supply. The problem with CMOS 555's at this voltage level is the current drive is almost nonexistent.

    If you want to reduce the current even more raise R3 to 1MΩ and R4 and R5 to 100KΩ, and drop C1 to 0.1µF. Using surface mount components it can be really, really small.
     
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