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Rube-Goldberg Type Random Number Generators?
stercor asks: "I've been considering random number generators made with easily-available materials. Living in Oregon might suggest photoelectric cells and rain. Or something to do with slugs (generation rate IS a factor, however)
My question is what other off-the-wall shelf hare-brained brilliant ideas can other Slashdot readers come up with? Please limit ideas to ones that would actually work." When I was younger, I was always intrigued by the rigs used by most State Lotteries. You know the ones: dump balls into a chamber, throw in a fan/vacuum combination to agitate the balls and to allow a random one to shoot thru a tube when the button was pressed (basically, a high tech version of your average BINGO machine). Has anyone else seen or built a contraption that does something similar but in a weird, roundabout or weird and roundabout way?
Check out RoboDJ, made by just one of the really cool, really clueful people that hang out on Kuro5hin.org. RoboDJ replaces the default WinAmp randomness with a weighted random selector that promises to be better than the default.
--Robert
I can't find my polarizers, so I can't test this, but I think you could rig something up with a cheap CCD webcam. If you look at a poorly lit image from a CCD there's an awful lot of noise, and the image sort of rides on top of this noise. If you took your cheap CCD webcam and kept reducing the light to it till you got mostly noise it'd be simple to capture and generate random data from. I was thinking of a shoebox with the sensor inside, USB cable coming through a small light-tight hole. Make a hole in front of the lens and stick a pair of polarizers in front of that hole. Rotate the polarizers to get a light intensity such that you get lots of noise.
If you snap a frame you'll get some random bits. Somebody could break the randomness by shining a really bright light through the polarizers, but as long as you can control access to the shoe box you'd be fine.
Chris Kuivenhoven is a thief, beware
ooh, yeah, i like that. very nice. well done.
to be honest, any similar sort of image will do. the image just needs to change *enough*. so like a webcam of a busy elevator or traffic intersection will do. or a webcam pointed at a television. or a dog kennel/chicken coop/horse stable. or just a picture of the person seeking the number (the human visage changes by subtle amounts all the time).
yeah, your version is a lot prettier. but i do think you'd need several chunks of incense, to make enough smoke.
... if you sample white noise from any source, you'll have a random value. Analogue synthesizers commonly use a reverse-biased diode of some sort to generate noise as it reaches the Zener region. You used to get special "noise diodes" - basically Zener diodes that were chosen because they were extremely noisy.
A good, simple white noise source is a reverse-biased transistor. Get an NPN transistor, connect the base to negative and the emitter to positive through a large (220k or so) resistor. Look at the voltage on the emitter - noise! Use an amplifier of some kind to get a useful voltage - you're not too bothered about hi-fi here, although theoretically distortion could skew the results (hint - what would clipping do to high and low values? What would crossover distortion do?)
Terry Ritter offers us "Random Number Machines: A Literature Survey" which discusses random numbers from noise and other sources. Well worth a look.
Ritter expounds on Geiger counters:
Now they also offer canned software - a random number generator based on radioactive decay.
I hate call waitin`~+~~~
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