Automatically Accept Membership Fees Or Donations


Whether you run a club or a hackerspace, collecting membership fees and accepting donations can be a pain. [MRE] from TokyoHackerspace has the solution, an automated machine that can accept cash from anyone who is walking by.

Members can choose to either donate or pay their membership fee even when the hackerspace administrator is not around.  The interface consists of two buttons, an LCD display, a place to put your cash, and a thermal printer that prints out two receipts (one for you, one which goes right back into the box). One of the coolest parts of this build is the banknote validator, which can work with over 100 currencies (in this case, it is programmed to accept Japanese bills). Despite the simple interface, a lot of thought went into this build. There are backup batteries for the real time clock, an EEPROM to keep track of all the accounting, and an Arduino as the brains of the operation. If you take a look at the project page, there is a lot of information on the Arduino code, the PCB layout, how to interface with the banknote validator, and more! Check out the machine in action after the break.

We would love to see the banknote validator used in other projects. Have you used one before or built something similar?

[Thanks James]

29 thoughts on “Automatically Accept Membership Fees Or Donations

  1. The best way to set one of these up… it controls the lab access door. Did not pay your dues? It’s not unlocking the door for you until you do. Nothing encourages people to pay more than cause and effect. Also make it loudly embarrass the person if they still try to access the lab even after being told, “you need to pay up deadbeat”

    Sadly the dealing with other people and their built in desire to get away with not paying is why I refuse to be an officer or lead member of any group. People really suck when it comes to money, or even stuff. I stopped going to the local “hackerspace” because of the turds there taking or “borrowing” my things or parts.

    1. Until now, I would have agreed with you.
      Funny thing though, so far, it looks as though members are actually MORE PROACTIVE about paying membership. This was the first month in which nearly everyone paid before the 15th.
      Either it is because of the novelty, or because they can do it even when us admins are not around. We shall see how it well it does long term.

      1. Our members are really awesome. And I love the space. We HAVE had issues in the past (and likely will in the future.. it is the nature of such spaces).
        We have found that in the long run, it is far better to focus on those who understand the benefits of paying membership. Those that just dont get it eventually disappear. But badgering for dues and collecting can get tedious and soul crushing :<

  2. I don’t need any box to do this. I’m always ready to automatically accept donations, or membership fees. If I’m asleep wake me up. I’ll be OK with it as long as you’re handing me enough money.

  3. I test coin and bill validators as well as coin and bill dispensers and recyclers. They are mechanical wonders. But don’t ask me how they validate the incoming currency, I don’t know, and if I did, I’d probably have to sign an NDA. I’m “guessing” (really) that coin acceptors use a Hall effect detector, as they don’t use counterweights or sieves anymore. Most of my testing is Go/No Go, bad ones go back to the manufacturer.
    Firmware levels distinguish between currency nationalities.

    1. I used to work in the casino industry, and before that, the non gambling games industry. There are a lot of different methods to do the coin validation. The two most common types are:
      1: Common in games and vending machines, as you guessed, a hall effect sensor. But it is more than that. Electronic mechs usually detect the roll time on the ramp, as well as the diameter of the coin, as well as the hall effect. All of these factors must coincide with the programmed parameters (even with proper signals, if they are shifted out of phase with each other, then it is still rejected).
      2: Typical of the casino/slot industry, this type utilizes a sample coin. The coin comparator is constantly measuring the response of an induced magnetic field through the sample coin. As the inserted coin passes behind the sample (there is a mirrored detection scheme on the other side), the two coins momentarily cancel each other out. Comparators can be highly accurate, but finicky. We usually installed older, worn coins, since installing mint new coins would reject up to 70 percent.

      1. I used to work in the casino industry as well and remember having to flash the firmware (or in some cases replace the chip) on bill validators whenever a new US bill came out. It was a pain in the ass to do that to over 1000 slot machines, not to mention the pissed off patrons who would yell about how your “rigging the machine to lose.”

    2. Bills are a bit more complicated, but follow the same form as the first type of coin validator. There are various optics, which record ‘tracks’ of data as the bill slides between the emitter and detector. Now, where you get into NDAs is the very specific wavelengths in which these operate, and the associated effects as passed through (or reflected off) the various inks and papers used in modern high tech bills. But it still boils down to:
      1: the same optic that detects the initial insert of the bill also records it’s length, and combined with the motor gear train provides the timing sync in which we expect certain markers to match up with recorded samples
      2: Modern validators use at least two or three tracks of ‘magic wavelength’ optics to ‘scan’ the full length of the bill. Comparing these to the programmed data serves as the primary form of validation. Many (such as this one) also incorporate bar code scanning, for custom printed ‘casino cash.’
      3: Validators now include some type of magnetic detector for finding bills with embedded wires, and again, combined with the optic on point 1 determine precisely WHERE that wire is.

    3. Here is a sample of the XML file which is generated when programming. This may be ‘bad’ of me to post, but even though this is a complete scan of a bill, you would not be able to fool the validator with this alone. I had to scan over 100 bills, in 4 directions (four hundred scans per bill denomination) in order to get enough data for the manufacturer to compile the firmware.

      As you can see, it takes something like 600 samples (I have not counted). and stacks all the tracks together. You can see the 00 bytes, which I am guessing represent lead in and out of the bill (?), i.e. the border around it.

      Face-up face first (FUFF)

      1. Its an xml, which strips in the comment box, so, from the top:
        600 – CollectLength
        0 – DataType
        The note data
        29 – ReadLength – the size of the bill?
        50 – SectionSize
        3090504 – SerialNumber – my machine, not the bill.
        100000 – Value (of the bill, as set by me during programming)

          1. I.T. actually encourages you to have a good mix of crisp and worn bills in the event you have to program (with hundreds of currencies in their database, its rare). Japanese take good care of their money. I had to ball up a few. ;)

            So far 100% acceptance with only two jams. I suspect those were due to the stiff bills landing on the printer PSU while exiting and bridging rather than falling out cleanly. Open the door and nothing is out of place. The bill is sitting in the bottom of the box.
            So no “physical” jams thus far.
            At least 100 bills of three denominations.

      1. Or at least I think I bought one… certainly looks like one, but the listing is in german. Looks like it even comes with a 5 euro bill to test it!

        Anyone know how to download updates and firmware for the device?

        1. Watch for NV10 vs NV10USB. Difference obvious in the name. With the old one you’ll have to wire up an max232-ftdi-usb or some such.

          Base firmware and currency set loading are all done over that serial/USB connection (you need a 12v supply). There are software tools on their site. Though hard to dig up. Currency sets are easy to find there though, sorted by device, with links to said tools.

          Also, not a plug, but I had several questions and their staff was very helpful and prompt. Just email them and they will walk you through it.

        1. Hahah Frank is loaded!
          Yeah we would eventually get around to denying entry. Thankfully, our ex/members have thus far been pretty respectful. Most tap out due to lack of time, rather than money. We had issues in the very beginning, but these days none really. Knock on wood.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.