Push switch, close one circuit, open another!

Discussion in 'The Projects Forum' started by matzy, May 9, 2011.

  1. matzy

    Thread Starter New Member

    Apr 14, 2011
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    I'm not so sure the title is very descriptive of what I am after.. so here goes an attempt to describe it a little better.

    I want to have a switch that when pressed, closes one switch/circuit and opens another.. or put another way..

    Three switches, A, B & C
    Switch B is ON
    Switch C is OFF
    Switch A is pressed and switch B goes to OFF, switch C goes to ON

    I'm sure there must be a simple solution to this but how to do it electronically baffles me, I guess a relay could be used, but not sure which or how to wire it up to achieve what i'm after.

    Thanks in anticipation of a reply :)
     
  2. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,387
    1,605
    Sorry, we need more input.

    A switch is on or off when you turn it on or off.

    Now if you have two circuits where you want one or the other on, both controlled by one switch then you want a double throw switch. "Double throw" means the switch has 3 pins that contact connect B-common one way, and C-common the other way. (Single throw is two terminals either open or closed.)

    If B & C both run from the same power then get single pole (one set of contacts). If they are separate then you want a double pole.

    Switches come in so many many ways, toggle, push button, turn key and many more. Get on any distributors site and have at it!
     
  3. wayneh

    Expert

    Sep 9, 2010
    12,112
    3,039
    A relay under control of a single switch would do this. It would require power to hold the relay coil "on" in one state, and no current in the other "off" state. If that's OK, done. If you need more than that, you'll have to supply more details (power source, load being switched, etc.)
     
  4. matzy

    Thread Starter New Member

    Apr 14, 2011
    14
    0
    ok, if I explain the use it may help to determine what I actually need..

    I am running a paintball game based on Resident Evil in July in which there is an autonomous sentry gun, within this game part of the objective is to disable the sentry gun by means of connecting it to a fake game prop "EMP unit", which I will call UNIT A. The sentry gun is UNIT B. A third unit "UNIT C" is a pyrotechnic sequencer.

    UNIT A "EMP Unit" is simply a case with a switch in it, this unit will be plugged into a cable out in the playing field that will lead back to UNIT A and to UNIT C "Pyro sequencer"

    UNIT B "Sentry Gun" runs from its own power source and basically I just need UNIT A to be able to disconnect power to the sentry, a kind of kill switch, i'm thinking something simply to break the power source to disable the sentry.

    UNIT C is triggered from a 6v to 30v pulse which can either come direct from a 9v battery in UNIT A, or from a 9v near UNIT C.

    So UNIT A will be triggered by using a "push to make" switch, when pushed I want it to kill power to UNIT B and to pulse power to UNIT C

    If it helps, this is the pyro sequencer unit so you can see how that works: http://www.easypyro.com/10-cue-sequencer
     
  5. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    1,605
    So unit A just has a single pole double throw switch. When pressed connect it such that the power to B is disconnected and power to unit C is connected.

    I'm assuming turning ON will be close enough to start the sequencer.
     
  6. matzy

    Thread Starter New Member

    Apr 14, 2011
    14
    0
    Yes ErnieM, what your saying does sound correct. I'm awaiting delivery of the sequencer and will be testing it out this weekend to see at what distance the 9v can trigger the unit, if it can be triggered from something like 10m away the 9v battery can be in unit A, otherwise it'll need to be at unit C. I need at least 10m distance to ensure the pyro are at a safe distance from the play zone.
     
  7. williamj

    Active Member

    Sep 3, 2009
    180
    32
    matzy,

    I'm really not sure I understand the sequence you're trying to achieve. From your description I get...

    Unit "A" disconnects unit "B" and unit "C" only works when unit "B" is diconnected.

    Is it that, when unit "B" is diconnected unit "C" instatly triggers pyro sequencer or does whomever diconnected unit "B" have to go to another location to trigger unit "C"?

    I'm thinking what you want is...

    There is a switch box somewhere out in the field. The switch in that box (in its current position) powers the "Sentry Gun" Somebody finds that box and throws the switch. The "Sentry Gun" loses power and the pyro sequencer is energized.

    Let me know if I'm close.

    williamj
     
  8. matzy

    Thread Starter New Member

    Apr 14, 2011
    14
    0
    Almost perfect for what were after, the only difference being that the switch box is not initially connected to the turret as the switch box itself is an item that is acquired earlier in the game.

    I was hoping that the switch box would have to be connected to a lead out in the field, this lead can be multicored for the two functions, one pair for the sentry, one pair for the pyros. The switch is then pressed and this disables the sentry and starts the pyro sequencer. Starting the sequencer is not the problem, it's more how I could disrupt power to the sentry. Is it possible to use some form of relay for this?

    Sorry I've not been too clear about what I want to achieve, all makes sense in my head, just not too good at putting into words a plain description
     
  9. williamj

    Active Member

    Sep 3, 2009
    180
    32
    matzy,

    What I've come up with requires three relays, one momentary push button, one keyed switch and appropriate power sources as well as numerous conductors, jacks and plugs and project boxes. The attached diagram indicates current flow and sequence of opperation. Actual wiring arrangement is left to you.

    The square push button icon to the left of the diagram represents the switch box that is hidden in the field. The dashed boxes in the diagram represent cables hidden in the field and/or powering the sentry gun and the pyro sequencer. For circuit power I've indicated two 6 volt (lantern) batteries connected in series to provide 12 volt DC because 12 volt DC relays are easy to aquire. The other power sources indicated are just that, indication of power source. Not knowing actual power required I couldn't be any more specific. Be carefull of wire size and length, long runs of conductors result in a significant voltage drop, so size appropriately.

    Sequence of operation is as follows...

    1 Keyed switch is turned to the on position, Sentry Gun (SG) relay coil is energized through Sentry Gun Control (SGC) normally closed contacts closing first set of SG normally open contacts maintaining current to SG relay coil opening the normally closed SG contacts (to PYRO relay coil preventing Pyro Sequencer from being energized before Sentry Gun is disabled) and closing second set of SG contacts energizing Sentry Gun, keyed switch is turned to the off position and key is removed preventing reenergizing of Sentry Gun after it has been deenergized in play.

    2 Switch box is located in play, Sentry Gun conductors are located and connected to Switch box,operation of push button energizes SGC relay coil opening SGC normally closed contacts deenergizing SG relay coil and deenergizing Sentry Gun. Switch Box is removed and Sentry Gun remains deenergized.

    3 Pyro conductors are located and connected to the switch box, operation of push button energizes PYRO relay coil through the now closed normally closed contects of SG relay energizing Pyro Sequencer indicating end of play.

    Hopefully I haven't missed anything or miss stated something. Let me know if this works for you.

    williamj
     
  10. williamj

    Active Member

    Sep 3, 2009
    180
    32
    matzy,

    It may be a good idea (for safety) to place keyed switches in both the Gun and Pyro Sequencer circuits to prevent accidental activation of either circuit before play begins.

    williamj
     
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