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This is a place to put info about the NoiseBridge DollarEater donation machine.

big mondo sensor on the larger of the two sensor boards is a visible light phototransistor:

A Coin Receiver / Sorter has also been dropped off - its main circuitboard is toast, but the solenoids and sensors are all there. It's much simpler than the dollar eater, but it will have to be connected to an Arduino or something to make it work. It has optical sensors which determine whether the incoming coin is a quarter, nickel or dime (others fall right out) and solenoids which enable or reject incoming coins. There is an electromagnetic coil on the back which I assume is to watch for highly inductive coins, aka slugs, so that the reject solenoid can be activated. This keeps slugs of the right size from being collected in the sorted coin towers.

The coin towers have optical sensors which can report when they are near full or near empty. I think the near full ones would be important, to tell Al or whoever to come and get some coins. The way the coin towers are assembled, i think it may be possible to just stick a coin roll tube in there and bundle it up - which is how banks require coins to be deposited anyway.

There are also solenoids for releasing coins, so if you want to be able to give change or jackpots or whatever...

from Jtfoote 04:33, 9 December 2010 (UTC)

I got two validators, they live on my hack shelf (highest and southmost on the eastmost shelves). They are "MEI" pn 251015176. Not much about them on the goog; I'm guessing pinouts and repair manuals are trade secret for obvious reasons. At $10 surplus, I'm not expecting them to be anywhere near prime. Worth it for the motors and sensors alone.

I figured out that power comes in on the blue/green two wire header. Seemed to "work" OK with 12V on green and ground on blue. Needs about 1 amp when the motors are running.

I couldn't get it to do anything more than suck in 1/2 way then spit out the bill despite trying several kinds of bills and many combinations of dip switches. I once got the rear motor to work in "coupon mode" (see small toggle switch on the side) but not repeatably.

My best guess is that the bill sensor doesn't understand new bills. It's also likely it needs some enable or handshake signals from whatever it was plugged into, but there were too many variables to reverse engineer. (Seems sensible that that a powered-up acceptor should default to not accepting if the main unit was off, disconnected, or crashed.) I think our best bet is to reverse-engineer the sensors and interface them and the motors to an Arduino.

If we can get some kind of voltage out of the main optical sensor, we could average it to get a rough yes/no go to stop blank paper spoofing. But I'm not going to worry too much about that.

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