Motion triggered valve

Discussion in 'The Projects Forum' started by Sluggo, Jun 24, 2012.

  1. Sluggo

    Thread Starter New Member

    Jun 19, 2012
    4
    0
    Hey everyone,

    I'm new to electric circuits and tried my hand at designing one. If someone could tell me if this setup will work or not that would be great. I'll also take any tips or advice.

    PIR is a Parallax

    Thanks in advance.
     
  2. #12

    Expert

    Nov 30, 2010
    16,320
    6,818
    This looks so very wrong. Better to tell what you're trying to accomplish. What motion is supposed to happen? What is supposed to happen if the motion happens? etc.
     
  3. Sluggo

    Thread Starter New Member

    Jun 19, 2012
    4
    0
    Haha thanks.

    It's simply supposed to activate the air solenoid when the PIR detects motion.
    The solenoid is to be activated for approximately 1 second and the device should have a latch so that the unit powers off after it is triggered.
    The leds, and toggle switch were to prevent the trigger from activating prematurely.
     
  4. #12

    Expert

    Nov 30, 2010
    16,320
    6,818
    You're going to have to dumb this down for me.

    Usually, when I get this dense, somebody jumps in and takes over, but this is Sunday night and they all seem to be snoozing.
     
  5. Sluggo

    Thread Starter New Member

    Jun 19, 2012
    4
    0
    Sorry, not a problem. By latch I expect the circuit to have a single (momentary) push button to turn it on. The circuit will then remain powered on until the PIR is triggered at which point the unit powers off (no current flowing anywhere) until the button is push again.

    I think this is similar to a SR latch? With the button triggering "S", "R" is triggered by the PIR at the same time as the air solenoid, and "Q" would be the power source of the whole device.
     
  6. wayneh

    Expert

    Sep 9, 2010
    12,145
    3,055
    Well, one thing at a time. Those LEDs need current-limiting resistors or they'll be instantly toasted. Start with 1k. You can cut that in half (people often use 470Ω with 12V) but I think they'll be fine as indicators with a lower current, and they'll last longer.

    What does R1C1 accomplish, your latch? C1 would have to be very large to give much time.

    What is PB2 doing? How is it related to the PIR?
     
  7. Sluggo

    Thread Starter New Member

    Jun 19, 2012
    4
    0
    Ok I've changed the picture around a bit. I messed up the info on Q4 it should read SPDT.

    R1C1 holds a charge so that when the relay returns to the right, current enters the transistor and triggers the air solenoid. In this case a mechanical relay is the latch circuit.

    PB2 will receive power from the PIR and direct it to D2 or the relay. By directing it to D2 you can ensure the PIR is not active before redirecting to the relay and prevent the relay from triggering prematurely.

    Relay Info - http://www.digikey.ca/product-detail/en/V23026B1102B201/V23026B1102B201-ND/2053789
     
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