Flipping Polarity to solenoid valve

Discussion in 'The Projects Forum' started by mrtyrel, Jan 8, 2013.

  1. mrtyrel

    Thread Starter New Member

    Oct 6, 2012
    4
    0
    Hi to all,

    This is my first post on the site, although I have referenced it many times in the past.

    I am trying to put together a circuit to control a pulse latching solenoid valve.

    What the circuit needs to do:

    When a tact button is pressed, it sends current to the solenoid valve to open the valve. When the button is pressed again, the polarity to the coil is reversed to close the valve.

    I have looked at Sequential Switching Bistable Bultivibrators and have found several schematics but without instruction as to the resistor type (PNP/NPN).

    http://studyvilla.com/multivibrator.aspx

    I have successfully achieved this with an H-bridge circuit but I am having trouble integrating it into a push button system.

    A schematic, link, or other instructions would be greatly appreciated.

    Ty
     
  2. crutschow

    Expert

    Mar 14, 2008
    13,056
    3,245
    The push button could trigger a 555 one-shot to give the desired pulse duration for the valve. The PB could also go to the clock input of a toggle Flip-flop such as the CD4013 to establish the direction of the H-bridge polarity (with suitable debounce circuitry for the PB output). A quad 2-Input AND gate, such as the CD4081 could then combine the FF direction output and the 555 pulse output to give the desired pulse signals to the H-bridge input.

    Make sense?
     
  3. mrtyrel

    Thread Starter New Member

    Oct 6, 2012
    4
    0
    Makes sense. A toggle flip-flop, to the best of my knowledge, is what I'm looking for. Rather than using an IC, I was hoping to physically build one with transistor, diodes, etc. The link in my previous post shows a schematic but doesn't specify what transistors need to be used.
     
  4. crutschow

    Expert

    Mar 14, 2008
    13,056
    3,245
    The bistable multivibrator in your link can use just about any NPN small transistor such as a 2N2222 or 2N3904.

    Toggle flip-flops are not always simple to build. To make them trigger reliably you may need to use a master-slave configuration of two latches. Much easier to use an IC. I'm not fond of re-inventing the wheel.
     
  5. NFA Fabrication

    Member

    Aug 12, 2012
    104
    3
    What kind of current is the "solenoid" going to draw? this would be pretty easy with two relays and a 555 and easily control 30 amps.
     
  6. strantor

    AAC Fanatic!

    Oct 3, 2010
    4,302
    1,988
    you could use a SPDT latching pushbutton. Here's a SPST version I'm posting because I'm drunk and too lazy to find you a SPDT version, but I hope you get the idea.
     
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