Help with Latching push switch

Discussion in 'The Projects Forum' started by hamopp, Jul 8, 2009.

  1. hamopp

    Thread Starter Active Member

    May 13, 2009
    68
    1
    Hi
    Not sure how to do this yet :confused:
    I need to switch a relay on\off, but using a momentary push switch.
    1st push = on and 2nd push = off, and need to be latched.

    Can a ic be used for this ?

    Could do with a diagram to show me the way

    Thanks
    hamopp
     
  2. hamopp

    Thread Starter Active Member

    May 13, 2009
    68
    1
    Hi
    Thanks for that, can this device be used for 2 switch's by using c2 as the other input ?
    so that 2 separate momentary push switch's can switch 2 separate relays (i need to be able to switch about 6 or 8 items), and this would keep the parts to a minimum.
    is there a CMOS ver of this device ?

    Thanks again for your help
    hamopp
     
  3. hamopp

    Thread Starter Active Member

    May 13, 2009
    68
    1
    Hi
    Thank you!, i shall now go and have a play :rolleyes:

    hamopp
     
  4. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    This is a cute circuit to get a push on/push off relay function. The relay coil voltage should be half that of the supply (5-6V for a 12v supply), and the resistors should be equal to the relay's coil resistance.

    ken
     
  5. Steve C

    Active Member

    Nov 29, 2008
    86
    0
    I did this with two transistors. Plenty of schematics online. Works like a champ. one switches on or off the other one.
     
  6. Mojo2005

    New Member

    Jul 18, 2009
    3
    0
    I dont have an idea on how to assign values for this very simple circuit (pushon-pushoff). Anybody can do will be much appreciated. I will apply it to my motorcycle to cut the ignition coil (12V) while on parking.
     
  7. Steve C

    Active Member

    Nov 29, 2008
    86
    0
    sorry, I linked a set-reset latch, not a push on push off latch. nevermind.
     
  8. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Mojo,

    If you look back to my previous post (#6) you will have values that might work. It's the same circuit only redrawn and with the extra set of SPDT contacts added to make it usable. The relay you use depends on the amount current it's contacts can handle, and that depends on the amount of current your ignition circuit draws. Do you know what that is?

    Ken
     
  9. Mike2545

    Active Member

    Mar 26, 2009
    116
    3
    There is an easier/better way to to this:
     
  10. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    Mike,

    Interesting chip. Ya learn something every day! :)

    I went back and re-read the original request.

    The simplest solution to hamopp's original problem would be a mechanical push-on/push-off switch controlling the relay (if that's even needed).

    For mojo2005, my little circuit would not work as it is always drawing current...on or off. As would your circuit. And he would have to add, minimally, a regulator and two capacitors to get 5V , a relay, and a drive transistor and base resistor. The simplest there is again a mechanical push-on/push-off switch controlling the relay...I think ;)

    Ken
     
    Last edited: Jul 19, 2009
  11. Mojo2005

    New Member

    Jul 18, 2009
    3
    0
    My friend told me its not the ignition line to be cut, its the CDI line. If that so, I need an ordinary 12 volts relay and I will try to use those values.

    Thanks Ken
     
  12. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    A 12V relay in that circuit will not work a 12v battery supply. The concept is that the relay coil voltage is 1/2 the supply voltage. An explanation: http://www.oldradio.com/current/pushon-pushoff.htm
    You would need a 5V or 6V coil relay.

    Ken
     
  13. someonesdad

    Senior Member

    Jul 7, 2009
    1,585
    141
    Ken: thanks for showing that -- I hadn't seen it before and it's just, well, clever. It only consumes 0.3 W when it's on -- not for battery use, but OK for a line-powered device.

    I also liked seeing the latching IC.
     
  14. Mojo2005

    New Member

    Jul 18, 2009
    3
    0
    Thank you Ken, it is noted.

    Mojo
     
  15. aboamal

    Member

    May 29, 2008
    14
    0
    I would like to share this circuit for the same function

    [​IMG]
     
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