Coin Mechanism for Coin-operated Projects I.

My first try to build a coin mechanism that works with quarters. A low-tech solution for projects that accepts coins to work. (12/25/2007)


I have this project in my mind since long time ago, but appears never is a good day to try it.


measuring the quarter. I started with something simple. A machine that accepts coins is expensive and the coin mechanism is quite difficult. My idea is to find the size of the coin to determine if it is a valid coin or not.


So, what I'm trying to do, is to collect only coins with the size of a quarter. A quarter measures a little less than one inch (about 23.6 millimeters to be exact).


material needed. First, for this project I did use a cutter, some tape, an old CD case and one small box. I did use a medicine box, as it is long and narrow.


I believe plastic or metal boxes will work fine, but this is only a test, so I'm not worried about how good is the material used.


Next, I draw two lines on one side of the box, the lower line is about 22 millimeters from the bottom, and the second line is about 24 millimeters from the bottom, almost one inch high.


After drawing the lines, I did cut the box using the lines as reference. The bottom side wasn't removed and it will help the coin to flip (in theory). See photos below.


draw lines cut box


I did cut the flaps from one side of the box so it can be glued in angle in reference to the slot. I made a slot in one side of the CD case, one inch high and about 1/8" wide.


Using tape, I installed the box in an angle, about 15 degrees with the opening to the right side.


cut in angle make a slot

Hey, what are you doing?
Dog Asking


So, here is my idea:


Idea A coin will be inserted at the slot, if the coin is smaller than a quarter, it will fall at the beginning of the opening. If the coin is too big, it will fall at the end of the box or simply, it cannot go thru the slot.


This simple configuration should "identify" the coin and can be used for a "coin-operated" machine for any project.


Let's see if this idea works:


A quarter Using a 25-cents coin.


It falls from the "quarter" area; works fine 4 of 5 tries.


A dime Using 10-cents coin.


It falls from the "smaller coin" area. Works fine all the time.


A nickel Using 5-cents coin.


It falls from the "smaller coin" area all the times that I tried it.


I believe this configuration works fine but needs improvement. I need to increase the angle (maybe 45 degrees) so the coin can fall as soon it reaches the opening.


The side opening at the "quarter area" needs a channel or something to catch the "good" coins and pass thru a switch.


Another improvement can be a narrow slot at the bottom of the box to measure how wide is the coin, if the coin is narrow, it will fall without reaching the side opening.


I hope I can improve this design some day.


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