Robust but simple, Latching Circuit needed!

Discussion in 'The Projects Forum' started by steevg, Jun 23, 2009.

  1. steevg

    Thread Starter New Member

    Jun 23, 2009

    This is my first visit to the forum (I'm only into hobby electronics - no formal training), and I'm hoping someone can help with what I think may be a fairly simple problem.

    I have a joystick-type switch, it has four "momentary" positions with a centre "off" return. I need a circuit which will latch each position of the joystick, when I select it. So for example, if I select position 1, and release the "Joystick", I need the circuit to latch - this latch will hold an input to another part of the circuit to ground (0vDC).

    If I then select position 2, I need the circuit to release from Position 1, and latch to Pos. 2. etc etc. I need to be able to select any position (1,2,3 or 4) at any time, and not have the latch drop out or disengage. On startup, it would be preferable to latch to position 1 by default.

    The circuit needs to have little or no bounce, and be very robust with a fairly versatile range of operating temps - say -10 deg Celsius to + 50 deg Celsius.

    Hope I've explained this clearly, and that someone may be able to provide me with a circuit to do the trick!

    Thanks in advance!
  2. HiProfile

    Active Member

    Mar 15, 2009
    I know it would be a crude way of doing it, but what about latching relays? The types with 2 coils would work to enable one possition when it disables the other 3 positions' relays. Say you hit position 1 - it activates the coil to latch #1, as well as the coils on #2-4 to "de-latch" them.

    The first reed relay I looked at opperates at -20C to 85C, and should have low-bounce, turns on fast, and should be fairly tough. Just won't pass much current.
  3. steevg

    Thread Starter New Member

    Jun 23, 2009
    Hmmm, thanks for your response . . . but I'm not sure this would work!
    I'm switching a video signal and have tried a make-before-break wafer switch, and even this has a certain amount of "bounce", which is evident as a glitch between signals.

    I'd prefer an IC or similar to do the job, as I think the switching is much faster, and many IC's also have de-bounce circuitry built-in! Unfortunately I'm not a techie, and don't have the experience to design IC circuitry myself . . but thanks for the reply.

    Ahh . . . hang on, just read your post again, you're talking about IC relays?? Not had any experience of them, do you have a spec or model/type to check out?