how does a machine know what coins were put in?
Coin identification is done by measuring electromagnetic characteristics of the metal coin, as well as its physical properties such as weight and/or diameter. When a coin enters the input slot, it rolls down a chute until it reaches two hook-shaped balance arms. These arms are designed so that a coin of the correct weight will depress the right arm enough to move a counter-weight on the left. The coin can then move past the correct arm and travel further down the chute. The coin must also have the correct diameter to continue. Coins, which are too narrow, slip down an exit channel and are rejected. Coins of the right size and weight will continue to move down the chute until they pass a powerful magnetic field. If the coin is a fake and is too rich in iron, a magnet will grab it and pass it out the reject slot. If the coin is genuine, it will continue down the slot at a certain speed, which will allow it to jump over a rejector pin. A release mechanism signals the machine to proceed.
ahh thanks!
P.S. Pouring salt water in a coin slot doesn't work anymore.
>>2
Cool
Wikipedia has only a little bit of info on it:
>The basic principle for coin detection is to somehow test the physical properties of the coin against known composites from coinage that is acceptable. Some of the first designs usage of weight failed to stop people from creating slugs of cheaper metal that weighed close enough to real currency to fool the mechanics of detection. Nowadays it is common to use a laser and electrical current to test various characteristics of the inserted coin that has virtually eliminated the problem as any significant amounts of currency are in paper and electronic form.
thanks!