Finally, this blasted device is starting to earn its keep!
After 13 kegs and an untold number of free drinks, your author hooked his dollar bill acceptor up to the Kegbot, just in time for Superbowl Sunday. With a custom cardboard chassis & intimidating signange, this Kegbot extension warns, "Hey! No more free rides, suckers, because I'm ready to guilt trip you into slinging a few bucks into the tip jar!"
History
We first wrote about dollar bill acceptors back in November 2004 (!), a time so distant it was back when your author referred to himself in the first person (and with little regard for capitalization.) Soon after filing our last report on the topic, we place the acceptor in a storage closet and forget about it for years.
It turns out that our Arduino tap controller hardware/software, Kegboard, is perfectly suited to the task of interfacing with the bill acceptor. Like the flow meters we use, the bill acceptor has an open-collector output that sends out a pulse train, one pulse for every dollar collected.
Since we weren't using the second tap/interrupt input (your author sadly only has one tap on his keg), we re-purposed it for listening to the bill acceptor. One devious hack to the kegbot core later and we have simple support for recording dollar contributions. If a user is authenticated while the bills are flowing in, we record that, too.
Construction
Obviously the most striking feature here is our lovingly hand-crafted designer cardboard chassis. Here are some construction notes.
Here's the MAG50B, making a triumphant return to the Kegbot blog. The enclosure is a little weird, since it is designed to sit in a vending machine; the front face hangs an inch or two beneath the bill-stacker box, so it can't easily stand upright on its own.
With a crowd on its way over for beer, this intrepid (and in all likelihood at the time, slightly drunk) hacker used the best materials available to him: this is to say, not very good ones. (Mechanical design prowess has never been our expertise.)
The sturdy plastic front face of the acceptor is removable, for bolting to your favorite cola machine or shoebox.
Using the face as a guide, we cut a small template in the bottom of the shoebox. It isn't shown, but in theory this orientation makes it possible to open the 'top' of the shoebox to remove bills from the bill stacker unit.
And here's the hole after being cut.
Next was the matter of power and pulse signal output. We will sheepishly omit providing details about the cruel solder job that became necessary due to a lack of parts (and time) -- but you should be able to fashion a nice connector using the details from our previous post.
A look at the logic board. I've surely voided my warranty, oh well.
The finished setup: success! Don't forget to use a pull-up resistor on the pulse output.
Total dollars collected: About $10, not including author's test dollars. Hey, it's a start..
Future Work
Clearly, the most important feature remains to be implemented: those with unpaid (or overdue) balances should be locked out of the Kegbot (or at least ridiculed via the LCD). Long-time kegbotters will remember this as an original feature, but one your author ripped out long ago for a rewrite.
We have grand plans for a "version 2.0" of the drinker accounting system, including user or group-targeted drink pricing, and account statements. We will soon reintroduce better support for solenoid-valve access control, too, so tell all your cheap friends that their freeloading days are numbered.
