is one that I've been wanting to build for a while now. I was
inspired by a design I saw on "Prototype This" in the episode where
they built a dog sitting robot. It had a ball launcher built into it
that used a similar design to this one.
I used a salvaged power window drive motor from a BMW to
power this. Any power window motor will work, and it will be up to you
to figure out just how to adapt it to the mechanism. This project page
is here to give you some guidelines and inspire you to try making one
It has a very simple wiring schematic:
Two micro switches and a relay take care of how the power is applied.
As you can see, when the motor is parked there is no power going to the
relay. When the ball gets dropped into the hopper and then onto SW1,
the relay is energized and the motor begins to rotate. As the motor
turns, a cam on the motor moves away from SW2 which takes
over power distribution to the motor. The arms swings around and
launches the ball which disengages SW1. The motor continues to turn
until the cam comes back around and bumps SW2 at which point the motor
stops and is parked, ready for another launch. Watch the video below for a more detailed explanation.