Getting awkward coins to work in machines

[Booldawg]

Why do people tell you to lick the coin when you're having trouble at a dispensing machine. Other than being wholly unhygenic we still do it. Does it actually work and why would it work?

[ummmm]

I really don't know. It either works or it's a COINcident....

[another-view]

*groan*

[Booldawg]

taxi for mrs ummmmmm

[ummmm]

I know I know...sorry :-(

[society]

a little spit goes a long way

[spudqueen]

Funnily enough I did this in a car park last week. It did work, and I amazed the fellow behind me by doing this.

[heathfield]

The speed of the coin as it drops through the mechanism is part of the testing process. If a coin, or even the coin slot, has dirt or grease on it (most have some) then the coin may drop too slowly and be rejected because of this. Licking the coin will lubricate it and make it drop more quickly. For an explanation on one type of vending machine coin tester, with timing as part of the test, see...

http://web.mit.edu/2....ester/coin_tester.htm

[Panic Button]

I think some of the machines pass a current through the coins to detect forgeries of the wrong mix of metal alloy.

Wetting the coin can improve the electrical connection for this test.

[sophie_1003]

I've never heard of this trick before, want to try it now!

[buildersmate]

Panic button is close to the true answer - but not quite. It isn't to do with electrical conductivity - but the change in magnetic field caused by the coin passing close to a coin as it falls. When you wet the coin it changes the magnetic field properties.
Sorry Heathfield, but has nothing to do with speed of the fall.
It does sometimes work - though not reliably.

[1955]

Just disgusting!!

[Panic Button]

Yes, totally disgusting 1955, but if you can't get your car out of a car park then neds must.

Perhaps more importantly, if you are having a chocolate attack, and that little bar of Cadbury's is taunting you through the glass, then what else can you do?

(Perhaps spit on the coin, and rub it with your finger)

[heathfield]

I worked on repairing slot machines, BM. Not every mechanism is coin speed dependent, but very many are. With those ones, too fast or too slow, and the coin is rejected.

[buildersmate]

I have worked for Mars Electronics International in a technical role. They are one of the largest global manufacturers of coin validations systems in vending and gaming. So unfortunately I do know what I'm talking about on this.

[Panic Button]

... and I like chocolate so I've got some idea about using vending machines.

[mibn2cweus]

If I got licked I reckon I wouldn't be coming back out for another go round either.

[rccatnap]

Spit happens!