The wife has had an old style “piggy” bank for years but the coins don’t always find their way to the pig and she likes to play slot machines. For her birthday this year I decided to combine both of those into the “ArduBank”.
The physical size of the bank is about a foot square and 16" tall. I used back glass from a real slot machine for lighted top. For the “reels” I decided the easiest way was to build a 3x3 matrix of LED’s, then print the 7’s on some self adhesive transparent film. To hold the LED’s in place, I used pill bottle caps.
For the coins (CDN) we have six dominations (actually five now that pennies are gone but I still coded in for them) I used a SparkFun 6 coin accepter. This generates an RS232 signal when it gets a good coin so it’s a piece of cake to use.
The display keeps track of the “total” in the bank (it writes the total to EEPROM). It also tracks the number of each coin so if you’re going to roll them up to take to the bank, you know how many you have of each coin type.
For the “slot” machine part, I wanted a payout, but paying out with money didn’t make much sense so I decided a “win” would be paid out in gumballs or jawbreakers. The lines for winning, 3 horizontal, 2 diagonal depend on the amount “wagered”. Thus a $2 coin and all five way wins are possible. With a .05 coin, horizontal middle line win only.
The reels spin down more or less like a real slot machine would and I found typically about every 30-60 coins you could hit a win. But depending on the denomination entered, it may not be a valid win. Sort of like a real slot machine where even if you win you can still lose.
The gumball mechanism uses a 5V stepper that’s attached to a 4 slot wheel (in the photos you can see the slot in the axle that the stepper shaft inserts into). A win rotates the shaft 1/4 turn where it pays out a gumball and picks up another.
Lastly, inside there is a keypad to “load” the gumball wheel and reset the coin total. With a few keys left over for future enhancements.
I decided early on to use an Arduino MEGA 2560 because it gave me a lot of pins for I/O and it’s running the 16K sketch.
Don’t have to worry about loose change be left around the house any more. Matter of fact, I have to hide mine now…