BEAM Projects > Symet - the Brass Beast

Finished Symet - the Brass Beast

the Brass Beast

Photopopper Schematic

FLED Solar Engine Schematic From
Junkbots, Bugbots, and Bots on Wheels©

Circuit used: Flashing LED Solar Engine From by Junkbots, Bugbots, and Bots on Wheels©

Construction Notes: The BEAM definition of a symet is a symmetrical bot. It uses its simple design to avoid obstacles with a single motor and no sensors. Check out Solarbotic's Bestiary entry on Symets.

August 2, 2008: I got started on my symet. I had purchased the Junkbots, Bugbots, and Bots on Wheels© book awhile ago and have built other symets, but this was going to be the first one that I documented. I used 3-1800uF capacitors for power storage. The ring that the positive leads are soldered to is from a laptop hard drive that died. The negative lead is soldered to the motor casing. A big fat wad of hot melt glue is the pivot (see the first photo below). The second photo shows the solar engine temporarily installed (and as noted below, it is not installed correctly; see schematic above).

After I put the pivot on, I felt the amount of tilt on the symet was too much, so I added a piece of brass shim as a bump ring and hot melt glued it to the capacitors. The motor had two nice holes for mounting on the top, so I used them to create a mount for the solar cells. This has the added benefit of making the panel removable. The cells I used produce a solid 3.5 volts in bright light, so I put two in series and managed to get a 7v output. I wanted to be sure I had enough voltage for the motor. The motor turns easily off of a 3.5 coin cell, though it doesn't have a lot of torque. To hold the solar cells together, I created a frame out of brass channel (see the fourth photo).

The last two photos show the completed "Brass Beast."

Side note on performance: I probably should have used a smaller motor and not made it as heavy. Though it does work, it is very weak. I have mocked up another circuit with the same motor and solar cells, but using larger storage capacitors, and still did not get a lot of torque. These motors will run very well on low voltage, they just don't have a lot of torque.

FRED Photopopper parts
Symet from the bottom
Tranistor Pairs
Solar Engine mounted on top of motor (yes, I know it is not hooked up correctly!)
Tranistor assembly
Out bump ring installed, along with solar cell mount

Solar Cell - Front and Back
(connected in series, put in brass frame)

Solar cells mounted, side view

The finished beast


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