Something useless for xmas
I needed a ~$5 gift for family xmas this year, and was at a loss. Then I remembered the Useless Machine from Make, also known as a “Leave Me Alone Box.” I had a $5 box from the thrift store, a smaller version of the one I used for my iPad Charger. After a lot of planning in AutoCAD and even more trial and error I came up with this:
It took me a while to figure out how to put it together with the cam attached to the lid, and my daughter suggested a rod & tube setup:
The cam is connected to the lid through a bearing and a brass “bicycle fork”:
When the cam spins, it lifts the lid enough for the arm to come out and flip the switch.
One thing that I did slightly different was use a 5V DPDT relay to reverse the motor instead of a DPDT switch. This allowed me to use a SPDT switch with a lower actuation force.