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AC adjustable timer, motion sensor timer

Discussion in 'Electronic Basics' started by [email protected], Mar 31, 2007.

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  1. Guest

    Heres the setup:

    1. I have standard household current (110v, 15 amp, AC) entering into
    a device.
    2. A momentary pushbutton switch is pressed.
    3. This feeds a current to a standard receptacle outlet, activating a
    4. The switch is released.
    5. Power is cut off to the light.

    Here is what I want to accomplish:

    1. When the pushbutton switch is released, the current flow to
    the receptacle continues for an adjustable amount of time (ex: 4
    seconds to 10 minutes).


    Motion sensors from any hardware store do this same thing. They have a
    switch to select 4 seconds, 10 minutes, or 20 minute activation. They
    are typically hooked up to a light socket or sold individually for a
    little as $10. I have found "AC Relay timers" on industrial supply
    sites, but they cost upwards of $50 and are very large units
    themselves. I don't need motion of proximity sensor capability since
    the device it switch activated. I simply need to keep current flowing
    for a length of time after the momentary switch is released.

    I guess, as a last resort, I could buy a motion sensor, disassemble
    it, and somehow bridge the motion sensor part. However, I'm hoping to
    accomplish this with premade unit of some kind, and for under $10
    (since ill be making large quantities.)

    So, does anyone have any ideas of suggestions?

  2. Randy Day

    Randy Day Guest

    Your description is almost identical to one
    I asked about a month or two ago, except I
    wanted power off for that amount of time.

    Here's a circuit that was posted here in
    response. It should work just as well in
    your case - just use the appropriate relay

    +12v \
    |------------------------ _ o o
    | )|
    | )| relay
    | _)|
    | | d
    | 1K ||-+ N-channel
    |_T_ ___ g ||<- mosfet
    +o o-+-|___|-+----+---||-+ s
    | | | |
    | | | |
    |+ .-. | |
    1000=== | |<--+ |
    uf /-\ | | 2M pot |
    | '-' |
    | | |

    (created by AACircuit v1.28 beta 10/06/04
  3. Matt M.

    Matt M. Guest


    Thanks for the info. I have never worked with making circuit boards
    before, so I have very little to no experience in this area. The
    schematic you posted looks simple enough for a beginners project, and
    I would assume that few parts = few dollars spent. If you have
    successfully made one of these, do you have any photos? If this
    requires 12v power, do I need a wall transformer, or can I incorporate
    one into the board?

    It still might be a little too tough to make these in quantities
    though, so any ideas where I can buy a board like this pre made?

  4. This describes working on home power distribution lines.
    If your part of the world lives in homes which include stairs, for sure
    you have used push buttons that activate the lighting of those caverns
    and darken them after some time. What I have seen were thermal units
    switching the power on and releasing after some adjustable time when the
    heater arrived at release point. Used in large numbers usually in
    cities. Ask any electrician.

  5. Dan H

    Dan H Guest

    In order to determine the best solution you need to specify what the
    load is going to be i.e. what is going to be controlled by the device?

    When you say "large quantities" how large?

    If you are going to sell these to be plugged in house current, there
    may be safety issues or regulatory issues - you should have a
    professional look at what you are doing or design something for you.

  6. Matt M.

    Matt M. Guest


    The switch device would be controlling a 100w floodlight. I believe
    that is about 1 amp. A switch might have 1 or 2 lights connected to
    it, and the devices would be daisy chained, with the total amperage of
    all the bulbs being less then 13amps, or about 13 lights.

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