Momentary latching switch...

Discussion in 'The Projects Forum' started by The Hammer, Jun 28, 2010.

  1. The Hammer

    Thread Starter New Member

    Jun 28, 2010
    I have a momentary usually open button that I am trying to use to keep a 12 volt line from a car closed to a relay powering a light air compressor. I want this button to effectively work like this: push the button once and it closes the line to a relay, push it again it opens the line to the relay. I've designed a different circuit to only keep the line closed after the button is pressed but not to open it again and have decided that this isn't what I am after.
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    Why not just use a mechanical "push-on/push-off" switch? How much current does the compressor draw?

  3. The Hammer

    Thread Starter New Member

    Jun 28, 2010
    A friend of mine has the relay currently, I forget what kind it was. I can't change the button type as I am doing a car project and am trying to use stock momentary buttons that have been disabled (needs some plastic pieces shaved to be able to be pushable) and not connected on it's PCB traces (which I will be changing).

    For references sake, the relay is going to be powering a pressure checking system on the air compressor. I didn't mention this because everything has been purchased and works already, I am just looking for an elegant solution to the lack of power control to the compressor system. A single button On/Off would be just great since there is also a surface mount LED I can use to describe "On" or "Off" that is already in place but not connected.

    I suppose that I wanted to just get a general idea for this and do the math and adapt it as I go.
    Last edited: Jun 28, 2010
  4. lightingman

    Senior Member

    Apr 19, 2007

    The solution would be to use a 'D' type flip-flop (4013). This will toggle the relay on and off at each press of the switch.
    I can post a schematic this evening if you wish...

  5. The Hammer

    Thread Starter New Member

    Jun 28, 2010
    That would be helpful, i'm sure I could google the information faster than waiting for a response. I trust the people and their expertise here better though. You probably know all the tricks that go with this device better than the descriptors I will likely find. Much appreciative.

    Nice to find someone with the same name btw.