The Rotating Tiger Cheese Box Construction Tips

       Home       Making The Top Making The Base      

Making the Base

To make the base you'll need 26 gauge magnet wire, a medium sized nail,
magnetic reed switch, 4.5 mmfd electrolytic capacitor, parts to fabricate      
a battery holder (A tuna can lid works.), an AA battery and a glue gun.       



Grab your second cheese box; this will be the base. Put two popsicle sticks together and drill a hole through them. Cut two slits in the top of the base that are wider than the thickness of a cheese box.
Push the popsicle sticks into the base.
 A nail goes through the holes in the popsicle sticks and through the top cheese box.
Adjust the height so that the edge of the top box is close to the top of the base. Glue the popsicle sticks to the bottom box.

The Electromagnet:


The first two electromagnets made were failures. I guess I should have made more electromagnets when I was a kid.

Both were wound on a bolt. It seems the diameter of the core affects how strong the magnet will be.

Wrapping the wire around a NAIL greatly increased the strength of the magnetic field. The wire is 26 AWG magnet wire.

The two failed electromagnets and the good one, (hot glued to the center of the box.) The failed ones ended up in the recycle bin.

Tips on coil making:
Make two disks of cardboard and put them on the nail. The nail head holds one disk in position.
 Use masking tape to hold the other disk. Here we are checking for height.
Wind the coil between the disks. This coil was made by putting the nail in the chuck of a variable speed drill, but you can wind it by hand. Cut off the end of the nail with a hacksaw.
Use hot glue to hold the wires together, then peel off the disks and glue it to the center of the cheese box.
Important: the nail must be iron or steel, not aluminum.

Tip:  Now is a good time to connect a battery to the coil and make sure it repels the magnets in the top box. If it attracts, reverse the battery wires. Mark the positive wire with a piece of tape for later.
Not a Tip:  Sorry, I have no idea how many turns of wire make up the coil. It's about 1/3 of an inch in diameter.
Tips on reed switch placement:
After many experiments, a good
location for the reed switch was
found. The location is critical.
The switch is not directly in front of
the electromagnet, but off to the side.
A later version, showing the offset.
The switch works better when in the EDGE of a magnetic field. Placing the switch directly under the magnets in the rotating box would result in very poor performance.

Notice the second (green) switch is larger and has a diode in series with it. This was one of several experiments.

The switches were burning out after about 20 seconds. I was only using 3 volts, two D cells in series, and the switches were rated at 90 volts. A different switch type was purchased (the green ones) but they continued to burn out. I had several theories on this.

Theory 1: The switches, bought on ebay, were Chinese crap. (They came from China, from a guy named "Jimmy")
Theory 2: The magnets were coming by about 40 times a second (5 revolutions X 8 magnets) and were too fast for the
                switches to handle.
Theory 3: As the magnetic field collapsed it produced a counter electromotive force in the coil which could reach over 100 volts.
                You could see the sparking in the switch and hear it as a clicking.

I put a nine volt battery in the circuit. The switch burnt out instantly the first time it was triggered.
A CLUE! Apparently "Theory 3" was the correct one.

The two D batteries were replaced with a half dead AA battery. The box rotated perfectly and the switch didn't burn out.

A homemade battery holder was made from a piece cut out of a tin can lid and everything was rather sloppily glued together with a hot glue gun.

The approximate positioning of the
top box with the electromagnet and
the magnetic reed switch.

NEXT, the old battery used was sitting at 1 volt. Would it work with a fresh battery?