The automagic M&M dispenser
4/19/97
When I first started working at
Borland
I thought it would be nice to put bowls of
M&M's
on my desk for the department to share. Little did I realize
that after a year of this I would have given out over a quarter ton of
M&M's!
After a while I became concerned about everybody in the department
reaching their hands into the same bowl. The fact that I didn't want
my bowls to be a vector for disease, combined with my natural
geekyness
caused me to build my own automagic M&M dispenser.
It has two chambers to hold both peanut and plain and it holds about
twenty-five pounds total. When one of the gearmotors turns, it rotates two
plastic discs. Each disc has a round hole in it. The first disc allows
a handful of M&M's to drop into a plastic measuring tube, then the second
disc allows the measured M&M's to drop down the chute. Finding 3/8" flexible
shaft couplings in Santa Cruz is not an easy task, so instead I used a
piece of 3/8" ID clear vinyl tubing and a couple of hose clamps - a
reasonable substitute considering the low torque. The motor is
activated by placing your hand under the chute, where there is an infrared
LED and and infrared sensor. When the beam (modulated at 40KHz)
is reflected off your hand and detected by the sensor a relay is turned on
which operates the 120V motor.
This was the first picture I took while testing the design.
The finished machine and the sign I put next to it.
View of the chutes where the M&M's drop down including a view looking up
one chute, showing one of the rotating discs
at the top and the infrared sensor at the bottom.
Schematic of the control circuit.
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