Minim 2WD
Wanting to make Minim a bit more competitive, I used high-current solar wafers (0.5V @ 40 ma) because they are light and powerful, though hard to solder and as delicate as a potato chip. The output from these wafers is sufficient to run the motor, so no solar engine is needed. Two 0.33uF gold caps were installed to meet the delayed start rule (it takes about 3 sec to charge the caps, then the motor starts)
I also built a twin-shaft pager motor, and used a V-shaped chassis, to overcome the tippiness and flexibility that caused problems for Minim.
The creation of the dual axle pager motor was the first step. This involved removing the paper seal over the brush end and carefully drilling a hole in the center of the plastic hub under the commutator (only certain pager motors are built this way--the ones from Solarbotics are not, the ones from Andy Pang are), gluing a tiny gear from a clock onto a 1/4" piece of music wire, then gluing the wire into the hole in the commutator. I used CA glue. Took 3 tries to get one working motor. And, in the end, it proved unreliable and sometimes wouldn't start without a push. Dead at the start gate!
Building the chassis was step 2. I used fine gauge aluminum sheet that I had preformed in May 2002 at a workshop at SAIT.
I cut the aluminum angle to shape, filed small round notches to receive the front axle and motor, then glued them in place with 'liquid steel' epoxy.
The front axle is music wire through a brass bushing. The axle is held in place by heat-shrink tubing. Large nylon clock gears form the wheels. At one point I lubricated this (and the motor bearings)-- bad mistake, had to clean it all out with alcohol. Motor never did recover completely.
Here's another view of the motor end, showing one of the two 0.33uF gold caps used for the 3 second delay.
You can also see how the chassis and mast are pinched together.
Here is the finished product with a tissue over the solar panel to keep it from moving while I took the photo. Before I gummed it up with oil, it worked pretty well.
The mast is aluminum angle, similar to the chassis. The two were simply pinched together and glued with 'crazy glue'.
The solar panel is a pair of 0.5V 40mA silicon chip types joined in series with silver solder for a total voltage of 1.0V. The wires run down the center of the "V" of the mast.
The capacitor-draining shorting wires required by the Solaroller rules are replaced here with a tiny finger switch. A single wire soldered to the bottom finger closes the switch and drains the caps.
Minim 2WD never did compete, though I hope to go up against Scott Martin's high-tech carbon-fiber super-roller at WCRG 2004. After all, he needs somebody to beat!
