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Scare Box

Discussion in 'General Electronics Discussion' started by davidbenjamindix, Mar 13, 2010.

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  1. davidbenjamindix

    davidbenjamindix

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    Feb 25, 2010
    This project is a scare prank box. I have a long rectangle box with a wire-cage door at the front. Inside is a homemade scary as crap stuffed animal attached to a dowel. There are extension springs pulling on the cage door so when a switch (problem) is activated, the cage door gets pulled inside, and the animal comes shooting out. I just got my remote control (4 channel wireless 12-volt DC remote control) in the mail, and the only thing left is to figure out how to set off a trigger/switch to activate the spring mechanisms. I figured there are 2 or 3 ways to do this....if you have another, please let me know.
    The first idea is to have a 12-volt motor make one cycle which turns a dowel that sets off the mechanism. The problem there is I would have to find some type of timer/relay that I could set so the motor only turns so far. I would also like the DC motor to operate in reverse so the animal can be pulled back in.
    Another idea is to get some type of switch that extends and retracts with the dowel attached to it. Another idea might be some type of electromagnetic switch (I have about 400 neodymium magnets) that extends and retracts when the remote signals open/closed circuit. That's pretty much where I am right now. The stuffed animal is so creepy. I used the same material from my homemade ghillie suit, and used fire-engine red eyes (which will have LED lights shining on them). The idea is to trick someone into thinking it's a ferrit or something, when they get close to the box, press the button on the remote, and this thing comes flying out. It'll be awesome. What can I do about the switch? thanks.....David
     
    Last edited: Mar 14, 2010
  2. CoCoMan

    CoCoMan

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    Feb 11, 2010
    Hum- that's quite an amusing project.

    If I understand it right, you want the motorized device to mechanically activate the switch, and that you want to critter to pop out suddenly, fast, really fast. Are you sure an electric motor will be fast enough? The best guess I have is maybe a small solenoid or electric actuator of some kind where the rod pops out when energized, but these can be expensive.
     
    Last edited: Mar 15, 2010
  3. Resqueline

    Resqueline

    2,848
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    Jul 31, 2009
    You could mount a micro-switch and wire it in series with the motor to make an electro-mechanical end-stop.
    With the proper mechanical setup you wouldn't need an exact stop either, and you could drive the motor through a capacitor that would only give it a sufficient push.
    Or you could make a solenoid that would negate the magnetism from one of your magnets - thereby releasing it.
     
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,419
    2,790
    Jan 21, 2010
    Another option is to have the critter on a spring, held back by a locking mechanism that is released by a solenoid.

    This would have to be reset by hand though.
     
  5. 55pilot

    55pilot

    434
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    Feb 23, 2010
    The simplest solution may be to buy the cheapest RC car/aircraft/boar transmitter package. It will come with a transmitter, a receiver and usually two servos. You can rig up the servo to push the button using what you are calling a dowel.

    If all you want to do is press the switch, a solenoid would be another simple solution, especially if you have already bought the remote control. You may be able to get a solenoid out of a door bell that has enough of a reach and force.

    You can use a motor and a piston, but now you are looking at micro-switches to stop it. You can make a relay based circuit that starts the motor when the relay is activated. The relay is deactivated when the motor hits a micro-switch.

    Using the motor to pull the critter back in is going to increase the complexity greatly. The mechanical design will be non-trivial. If you want to critter to jump out, you will need to use a spring like you are doing. The critter will not move fast enough with a motor to be worth-while.

    ---55p
     
  6. davidbenjamindix

    davidbenjamindix

    21
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    Feb 25, 2010
    I think making a solenoid is the answer....but! I tried making a homemade solenoid. It's not working. I'm using 12V battery (2x 6V), a plastic pen tube with a nail for the core, and thick steel wire tightly wrapped around the pen tube. I think perhaps the wire is too thick or needs to be insulated?. ..and should i try and find a metal tube instead of plastic?
     
    Last edited: Mar 14, 2010
  7. 55pilot

    55pilot

    434
    3
    Feb 23, 2010
    The wire needs to be insulated. You want the current to flow through the length of the wire, not just jump from turn to turn. If you did exactly what you have explained, you have most probably killed your batteries and may have come close to starting a fire.

    You need to get your hand on insulated wire, usually called magnet wire or enameled magnet wire. You need to have enough of it in your coil to limit the current and not so much that there is not enough current flowing. Remember to strip the ends, which is not the easiest thing to do. Burning the end with a match or a lighter and then scraping with a fine sandpaper works well.

    After you have all of that figured out, you need to install a return spring and make sure that the whole mechanism moves freely. By the time you have all of that fine tuned, you may be better off buying a cheap door bell and yanking this whole mechanism out of it.

    ---55p
     
  8. davidbenjamindix

    davidbenjamindix

    21
    0
    Feb 25, 2010
    55pilot thanks so much. i'll probably just buy the doorbell.
     
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