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How to get a rotational force of random intensity?

Postby arcadiagiulio » Thu Aug 12, 2010 11:04 am

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Hi. I'm working to a mechanical slot machine. I found this problem: how to randomize the response? I need a rotational force for each cylinder (to move them), of random force (to get a random result).

Re: How to get a rotational force of random intensity?

Postby Scrupulous » Thu Aug 12, 2010 3:50 pm

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Magic 8-ball comes to mind...

Yes - definitely

Re: How to get a rotational force of random intensity?

Postby JoeWaisman » Thu Aug 12, 2010 8:31 pm

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ACTUALLY Scrupulus is correct! The magic 8 ball uses a random number generator to select it's answer...the same random number generator can be applied to your idea.

If you know an EE the solution to this is EASY. You need: A low power processor with a built in clock, a way to program it, and a motor controller - preferably with a digital input of some sort, oh and 3 motors, one for each wheel/cylinder.

The chip would have to be programmed to generate 3 random codes, with minimum and maximum values mapped to your desired range. The outputs would then be sent to each motor controller. The motor would accelerate based upon the output of the motor controller.

If you're new to this world, but aren't afraid to do a little coding and wiring then you can build a prototype easily by:
1) Get a parallax board. Stamp Basic is very easy to program in and ideal for quick prototyping. The draw back is that the board is not very powerful and can't easily simulate complex circuits...like a cell phone for instance. This draw back is not relevant here.
2) Buy a dozen or so transistors (they're easy to burn up)
3) Get some 20 gauge *solid* wire or whatever is appropriate for your board.
4) Program a random number generator into the board so that the output varies from .2 seconds to 2 seconds of "ON" to say pin 1. I seem to remember the manual telling you how to do this and giving code examples.
5) Take the output of pin 1 and send it to the "enable" input of a transistor...check that polarity is correct. A little puff of smoke means it wasn't.
6) Connect ground to the input of the transistor assuming it is the NPN type and not PNP.*
7) Connect the output of the transistor to the motor.
8) Connect the free terminal of the motor to + assuming NPN was used.
9) Test: Run the program...works, yay.
10) Code the program to run based upon [button] input. Again the manual tells you how to do this and gives code examples.
___________________________________________
"The horse is here to stay but the automobile is only a novelty, a fad."
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*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions

Re: How to get a rotational force of random intensity?

Postby arcadiagiulio » Fri Aug 13, 2010 2:25 am

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JoeWaisman wrote:(...) [A] random number generator can be applied to your idea.

The chip would have to be programmed (...).


You have forgot that I need a mechanical slot machine. Also, my knowledge about chips programming is 0. I know something about software programming, but nothing about chips (except potato chips :mrgreen:). So, I need an old-type slot machine, with no chips, transistors, etc.

P.S. I've not specified it, but I need to build it with the lowest cost possible. I'd like to spend < €50 [Please don't joke - I'm a noob in the design field :oops: ].

Re: How to get a rotational force of random intensity?

Postby JoeWaisman » Fri Aug 13, 2010 10:57 am

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Are you trying to keep the cost of your prototype below 50 euros, or the cost of your final market product below that? I suspect you want a cheap prototype; on the off chance that you were talking about the final market product....

In quantity the parallax board would be replaced with an IC chip and circuit board...and maybe a 555 chip if that weren't already built into the IC...so in quantity, your parts list for each device would be:

$0.30-$5 each IC chip
$0.01-$1 Transistors/Miscelaneous electronics & wires
$0.30-$10 3 Electric Motors
$__ - $__ Physical components: lever, box, wheel, gears to turn wheel, belts, etc*

$8 rough average total cost of electronics...not sure how that translates to euros

*I don't know how big your components are or how they would fit together, so there's no way to guess at this.

EE's are all over, you could probably get someone to program the chip and set everything up for you. It might not be cheap at first, but it would get the job done.
___________________________________________
"The horse is here to stay but the automobile is only a novelty, a fad."
Fun links:
*http://www.scribd.com/doc/441708/Bad-Predictions-About-Great-Inventions

Re: How to get a rotational force of random intensity?

Postby arcadiagiulio » Fri Aug 13, 2010 11:57 am

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JoeWaisman wrote:Are you trying to keep the cost of your prototype below 50 euros, or the cost of your final market product below that? I suspect you want a cheap prototype; on the off chance that you were talking about the final market product...

I need to build just 1 machine - "for personal use". However, $1 is about 0.75 €.

I said you, I have no knowledge about wiring and chips programming.