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need HELP with a high school prom project PLEASE!!!!!

I am making a prop for my sons high school after prom which starts right after the prom ends and goes to 4:00 AM. This gives the kids an alternative to getting drunk or in trouble other wise. It's a great program. This year I have been asked to make the small scale replica of the ball that drops at Times Square on New Years Eve. I have made the ball and intend to have it go up and down on a threaded shaft via a linear motor. I need a way to make it stop at the bottom, wait 2 -3 minutes and then reverse the DC current so the motor reverses and send the ball back up to the top. When it gets to the top I need it to wait 2-3 minutes, reverse the polarity to the motor so it goes down again. I will need this continuous motion of up and down to last the 4 hours of the party. I had found a motor that I thought would work on Ebay but my PC crashed and I never got to bid on it. I'll hopefully be able to find another one somewhere. Once I procure the stepper motor and lead screw I will still need help with the up, down and time delay part of this deal. Any help or guidance would be greatly appreciated. They have also asked me to make a device that they can attach a mock up Planters peanuts can to that will make the mock-up turn, and tilt so the can will empty out peanuts and then go back to the upright position. This is to replicate the one that is now in Times Square. If anyone can help me with that project I would also be most appreciative.. Sources for necessary parts would be a Godsend. Thank you, Rudy

Reply to
rudyeb
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Piece of cake, Rudy. This can be done using relays, timers and sensors or more elegantly and for a little bit more money using a programmable controller like the ELK-MM440 (aka "Magic Module"). Note: I sell these so I'm not exactly unbiased, but choose for yourself how you want to accomplish the task.

The Magic Module has inputs which you would connect to inexpensive magnetic sensors (contacts) of the same variety commonly used to protect doors or windows in an alarm. Mount sensors at the top and bottom of the pole. Place magnets where they will trigger the sensors as the ball approaches. Use one relay to interrupt power any time either input is tripped, wait 2 minutes and restore power. Throw a secondary DPDT relay with another of the MM's outputs to invert the DC power whenever the top input is tripped. Release these relays when the bottom input is tripped.

This will cause the motor to raise the ball upon power-up, wait two minutes at the top and start the descent. Upon reaching the bottom the ball will stop, wait two minutes and begin another ascent. If this sounds too complicated it's only due to my poor communication skills. It's actually a very simple circuit to build.

If you don't want to spring for the ELK Magic Module, you can do pretty much the same thing using dumb timers and relays, either from ELK or Altronix. The difference will be around $1C.

Reply to
Robert L. Bass

Lot of this type of stuff on robotics sites. I've got a page below showing some simple motor reversing circuits. You can get a Black and Decker 6v cordless drill at walmart for ~$8 and use it for the lead screw drive. Are you looking for purely mechanical, or do you want computer control?

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Reply to
Si Ballenger

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