Making people pay for their beer at parties

A common problem at parties and get-togethers – although we don’t remember this happening – is regulating the amount of alcohol people consume. [Mike] came up with an interesting solution to make sure people don’t drink more than their fill by building a vending machine out of a minifridge that allows you to keep track of how many cans someone has taken.

[Mike] added a magnetic card reader on the side of a minifridge that allows any card with a magnetic stripe – a library card, credit card, or school ID – to serve as a unique identifier for each party guest. This card reader is connected to a Raspberry Pi which handles all the registration and eventual payment processing via Venmo

The mechanical portion of the build is a series of ramps built inside the fridge. At the bottom of this series of ramps, a servo controlled by an Arduino dispenses one can at a time when commanded to by the Raspi. The vending machine has a capacity of only 24 cans, but [Mike] says that could be improved with some CAD designed ramps inside a more modern fridge.

39 thoughts on “Making people pay for their beer at parties

  1. you know that there will be the overly agressive guy that nobody invited (or say they didn’t invite), who will just try to trash this to steal your beer!

    Best whip up a bouncer!

    1. I was thinking along the same lines of overly-hammered person gets tired of the idea of swiping a card and just prys this thing open for the goods lol

  2. so, i can use my Debit card, Credit card, Subway card, Drivers license, and starbux gift card as unique IDs? Seems like I’ll be double-fisting it all night long!

  3. This guy sounds like he throws awesome parties. I bet the potted plants have retina scanners to catch the guy puking into them.

    Why not do what the rest of us do? Drink as much as you want, and if you need to, crash on the couch.

    1. Charging for alcohol is a great way to get the tax man interested in your parties.

      Hard to throw a rager with 24cans. Something similar to

      I think a better implementation would be an ID scanner that only unlocks if the ID is of the appropriate drinking age.
      2.0 should be a version that opens the valve to a keg line. Most mini-fridges can hold a couple cornelius kegs, maybe even a pony keg. If you put the valve as close to the tap handle as possible there shouldn’t be too much of an issue with air getting in the line.

      1. It wouldn’t be the tax man I would be worried about. It is the liability from selling alcohol without licenses and then liability from someone drinking and driving after you served them.

      2. Right, the tax man is the agency which -holds- you liable for selling without a license. The whole point of a license is so they can enforce taxes.
        In the US anyways that is your states’ Alcoholic Beverage Control Agency along with the Federal TTB(formerly ATF). Since they issue liquor licenses it is their laws you are breaking, their agents who arrest you and state/federal prosecutors who chage you.

      3. I understand that, but still not the tax man. More of the lawyer of someone who wrecked after I sold them illegal alcohol.
        Selling someone alcohol when licensed is one thing, no licensed selling is yet another can of worms.

    1. “going Dutch” refers to splitting a charge equally.

      Paying your fair share from a vending machine is common sense, splitting a dinner bill at a restaurant with your date is ‘going Dutch’.

      1. No, I don’t think so. If you google it you’ll find links to wikipedia and urban dictionary which say something like “each person participating in a group activity pays for himself, rather than any person paying for anyone else”. Admittedly Wikipedia goes on to say “There are two possible senses—each person paying his own expenses, or the entire bill being split (divided evenly) between all participants.”.. but I suspect the latter version is a more recent American re-definition as I’ve never heard that use myself anywhere in the UK or, actually, whenever I’ve been to the US.
        I’ve known Dutch people to pull out calculators/phones at the end of an evening to calculate exactly what everyone is owed. It’s very embarrassing. The rest of us just over pay on an even share and leave the person with the calculator to his own machinations.

  4. LOL; Intentionally or not, Brian is being somewhat a troll here :) using a browser word search at caribou vending doesn’t bring up the word beer all. After pointing that out I really wonder in how may States, Counties, Cities it’s not legal sell to sell beer without the appropriate licenses? Pretty likely at least one of those entities is going to trip your ass up if you try to sell/serve beer this way. For groups like hacker spaces etc. this sort of project would allow the group to keep cold soft drinks handy, keeping %100 of the profit from the sales for the group. While not the most secure drink vending machine, the most that thieving assholes will make off with is the drinks.

  5. This is just plain old stupid. Not only is it illegal to charge people for drinks without a liquor license, if the machine decides to cut someone off after they swiped their library card a few time, they can just instead swipe a different card and start the count over.
    I get the idea, but this is just a total failure in all aspects.

    1. No this is an epic win. After the the drunk has run out of the usual cards like library card, drivers licence, student ID, etc they’ll eventually swipe their credit card.

      Instant identity theft.

  6. then the next day he can go through the data and find all the swipes thats data conforms to Credit/Debit card specifications and go on a spending spree.

  7. Blind Pig alert:

    Cops just *love* stuff like this, particularly around college campuses; it’s a favorite way of busting house parties (even passing the hat for the next keg qualifies in a lot of jurisdictions). You’re likely to wind up with all your stuff impounded, your place searched (I mean *searched* – don’t expect to get everything back) and some huge legal expenses.

    Voice of experience here.

  8. Why not get the Pi to drive the servo with a GPIO? I doubt the timing is too critical. You could probably even use the audio output to generate a suitable waveform.

  9. Just give everyone and RFID tag bracelet. They swipe it against a reader which checks the code against how many time the person has been served. If less than the limit, the person gets served. Connect it to an automated keg system and cup dropper and you’re set. Could have heaps of fun with it. If you want them to not get smashed quick, only let them have a alcoholic drink every so often. If they swipe within the time limit, it will pour them chilled water or soft drink.

    1. WOW What Fun!!! Stealing someones identity (or destroying it, depending on what else this fridge dishes out – mushroom shake, a meth habit, sex change?) is what i’d be more interested in!

  10. A solution to a problem I’ve never seen before…Wouldn’t a simpler solution be to either get everyone to bring a crate or just attend other peoples parties? Either one is less likely to leave you a social leper.

  11. Maybe i am from another time… but…
    When we have a Party either the host pays or everybody brings something.

    I would be very offendet if invidet to a party and had to swipe for every drink.
    On the other hand if the darn thing keeps track thats just stupid profiling.

    But maybe i just got friends and not assholes who are “friends” that try to screw me over.
    But thats getting the norm nowdays, what some people consider friends i would not even look at or even speak to.

    1. Same, I’d be pissed, on the other hand I know people who will drink you out of house and home.

      Who are truly nice guys, and friends just big drinkers.

  12. I wish HaD had a no code no post rule. Mostly I want to see if the card details are hashed before being entered into the database.

  13. Op is a bad party host… =/ i wouldn’t go to his parties after knowing this… or i would bring my own beer and blackjack and hookers…

    Meh… forget the blackjack…

  14. I don’t really get why he bothered building a “party fridge”, because chances are nobody visits him anyway with that attitude.

    If you have a problem of running out of beer at parties, you obviously haven’t bought enough. And if you are going to be a cheap bastard and make your guests pay for the booze, don’t even bother throwing parties.

    Also, what kind of a lame party is that? Beer only? Who throws parties without liquor? This guy sickens me.

  15. With the Coke-Sprite demo, it’s a ??? game as to what you get. Who has just one kind of beer at a party unless it’s a keg. And yes some good beer does come in cans, if you can order 5M units at a time.

  16. I’m working on something similar for large scale events. We’re using magnetic card readers on r-pi’s to keep track of how many times a user gets food from the lunch line or if they attended a talk at the event. Ours is written in python and has a little more functionality, but the concept is the same.

  17. That’s a little depressing. Usually after parties we always find we have an excess of booze. I distinctly remember a friend having so much beer left after a party she foisted beer on us every time we were round hers for about a month afterwards!

    Get some better friends or go to someone else’s party man.

  18. It’s kind of funny to hear how parties are held…

    Where I’m from, everyone brings their own booze and something for the host, like a beer.
    Because he/she is the one that has to deal with complaints from the neighbors, and the cleanup after the party.

    All of the empty bottles, which have a $ 0.3 deposit each, is left at the host to pay for any damages that might have occurred.

    The host always has a non-profit beer-reserve for the ones that forgot to buy beer, which is also legal in my country.
    The vending machine might be one of these beer-reserves.

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