[Vending Mexico] plans to design, build, and sell their of vending machines. You’ve got to start somewhere so they’ve built this prototype. It offers a range of vending features but was built with parts we’re used to seeing in hobby projects.
The one challenge they didn’t take on is the ability to identify coins and make change. You can see they’ve chosen to use a Coinco Guardian 6000 changer. But the custom circuit taps into the device, identifying how much money has been dropped in the slot, and controlling the coin dispenser to make change. Right now there is only one item to choose from; some packs of gum stored in a cardboard partition with the typical metal corkscrew — driven by a servo motor — to dispense the product. Just below that partition there is a row of IR LEDs which have a complimentary set of IR phototransistors. The machine uses these to detect when product has dropped through. This way if your candy gets stuck you get your money back.
The user interface is shown off in the video after the break. It uses a set of seven segment displays for feedback. An arcade button is used to select the desired product. The video dialog is in Spanish but we had no trouble telling what is being shown off even though we don’t speak the language.
We can’t remember seeing other scratch built vending machine. It seems all of them have been hacks on older commercial vending hardware.