Coin operated printer terminal

Thread Starter

The Milch

Joined Sep 13, 2018
1
So I saw this today https://weburbanist.com/2015/11/08/story-dispensers-street-printers-vend-free-short-stories/ and found it with great interest, I then started to look up these machines and came across a video of a man who made a coin operated one, so I wanted to try and research the components that are needed, so what I have found is that I need a raspberry PI, coin mechanism, and the terminal printer, that's all I've got, I've spent close to probably 3 hours trying to see what is needed, what software is needed to trigger the terminal to print once a coin is accepted and a program to randomise a short story, as I've gotten to this conclusion I want to see who who would know more about this system, I think this would be a great idea for my godson as he loves to read and he can save up for his games, your help is greatly appreciated.
 

JohnInTX

Joined Jun 26, 2012
4,787
Welcome to AAC!
You've pretty much identified what is needed. Essentially, the system polls the coin drop while idle then when it sees the coin(s), pulls a file from the SD card and prints it.
Search 'Airpax' and 'Greenwald' for relatively cheap coin drops/slides. You also might contact the parts dept. for your local coin-op laundry service or vending company. These have simple a simple switch or opto-interrupter that gives a momentary signal when a coin rolls by. The coin discrimination is done by mechanical means. For a non-critical project like this, you could also roll your own by fabricating a coin-guide/slot and using a simple opto-interrupter to make the signal as the coin goes rolling by. Glue a couple of K&S 'C' channels to a flat plate and mount the opto to that. K&S stuff is available at hobby shops and most hardware stores. Maybe you could retrofit the old piggy bank. There are many ways to do it.

The basic photo-transistor optos should be good enough. You can also use one with a 'logic IC' that has built-in signal conditioning. The coin detector connects to an input port on the rPI and your software does the rest. The rPI should drive the printer itself rather than act as a 'switch' between a PC and printer. That approach ain't trivial.

Nice project. Have at it and post your progress and questions.
Good luck!
 
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