Cash-Caching Automaton

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Revision as of 23:57, 5 November 2012 by Tylercrumpton (Talk | contribs)

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Born On:
23:34, 18 October 2012 (CDT)
Last Updated:
23:57, 05 November 2012 (CDT)


The Cash-Caching Automaton, or "CasCA", is a machine designed to dispense coins to Makers for use with the drink, candy, and snack machines. Many people don't carry around cash or change, but the vending machines at the shop currently only accept coins or dollar bills. This machine will make use of personal accounts assigned to Makers that may be funded by PayPal, Bitcoin, and other manual forms of payment, like checks or cash. Below is the current list of desired features:

  • The machine should be able to reliably dispense a user-selectable number of quarters (not too few, or too many)
  • It should be able to offer multiple forms of user-authentication:
    • Username + password
    • Makers door-authentication thumbdrive (plus optional pin number/password)
    • (Possible) Smartphone authentication via QR displayed on screen
    • (Possible) Other smartphone authentication: NFC, Bluetooth, WiFi?
    • (Possible) RFID tag
    • (Possible) Google Authenticator
  • Accounts should be automatically fund-able at the machine via PayPal or Bitcoin
  • Accounts may be manually funded via check or cash
  • Can show account balance on screen
  • MUST have secure connection to a secure database for transactions
  • Easy to physically refill with quarters
  • Automatic email notification when low on quarters
  • Display a message on a screen when low on quarters
  • Able to dispense coins without an account when using PayPal or Bitcoin
  • Physical and account-based intrusion detection and notification



We've contacted a guy out in Trinity who says he has a few change-machines. They are small, tabletop units that would work quite well for the quarter dispenser, since it would already handle giving out quarters, checking for low levels, and we could even attempt to retain the bill-to-quarters functionality. It would also already be lockable and theft-resistant.

If that falls through, another proposed design for the dispenser is to use a tall 1" i.d. pipe (PVC) to store the quarters to be dispensed. The bottom of the pipe would have small slot where a single quarter may slide though and a sensor to detect whether there are any quarters remaining. A servo would move forward to push a quarter out of the slot, and move back to let the stack of quarters slide down. A diagram will be posted to more clearly explain the machination if we are unable to purchase the change machine.




  • method of data entry for account usage and USB drive usage
    • Raspberry Pi?
  • NFC and some RFID
  • Tiny combined USB BT and WiFi card?


Cost Analysis


Progress Log

22:57, 5 November 2012 (CST): The small desktop change machine has been acquired and tinkered with. Jimshoe has hooked up a switch that will manually trigger the dispensing of up to four quarters at a time. This switch will be replaced by a transistor or relay that will be controlled electronically.

Design Files