how do vending machines recognize whether the coins are correct?
also what about dollar bills?
Chief’s Domain - http://www.seas.ucla.edu/~ravi
Used to be, they checked the size and weighed the coins. It may be possible to make a slug the same size and weight of an actual coin, but not worth the effort for a soda.
Bills, OTOH, are printed with magnetic ink. The reader checks the magnetic pattern to see if it matches.
“East is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does.” – Marx
Read “Sundials” in the new issue of Aboriginal Science Fiction. www.sff.net/people/rothman
Try http://www.howstuffworks.com (I think that’s the url, anyway).
Didn’t see it on How Stuff Works, but try this site. They make the coin recognition equipment and state that it tests 6 parameters and compares it to what was entered during the programming stage.
http://www.coges.it/English/eur10b.htm
Ooops, forgot about bills. Same company, bill recognition.
http://www.coges.it/English/TP95A.HTM
Hmm, I’m pretty sure I saw a short piece about the various techniques used for the recognition of paper money at howstuffworks, probably in the daily questions archive. Too lazy to look it up, though.
Mikan, it could very well be there. All I did was type vending machine into the search function. It came up with zilch.
When I was in Jr. High school (about 10 years ago) I had a friend who would photocopy dollar bills and put them in the school Coke machine. They worked fine. Not only did he get a free soda, he got 50 cents back, too! Vending machines are undoubtedly a lot more sophisticated now than back then (paper money probably is, too), so I doubt this would work today. I just know one of you clowns is gonna try it, now, “in the interest of science.” Don’t. If I were less lazy, I’d quote “Dr. Strangelove” now.