Introduction: How to Build a BEAM Robot

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A symet is a BEAM robot that stores electricity from a solar cell until it has enough energy to make the motor twitch. In this instructable i will show you how to build your very own BEAM symet! If you would like to see videos and read more about it then please visti my blog at, ! Thanks and hope you enjoy :) ! CREDITS: "junkbots,bugbots, and bots on wheels"

Step 1:

Step 2: BEAM Symet Parts

To build this robot you need the following parts.

1x resistor between 1k and 10k ohm
1x 2n3906 transistor
1x 2n3904 transistor
1x motor (the fatter and flatter the better!)
1x solar cell (volts vary depending on motor)
1x aluminum wire
3x identical capacitors between 470 - 4700 micro-farads
1x flashing LED or blinking LED (no exception!s)


soldering iron
needle-nose plyers
wire cutter


heat-shrink tubing (to get traction by adding to the motor shaft)

Step 3: Preparing the Motor

The second step is to get your plyers, sandpaper, etc... and stratch the motor body until you see a different shine of metal appear. This allows the solder to stick to the motor body so we can solder on our capacitors. after you have stratched the motor enough then solder the (-) capacitor leads to the motor body.

Step 4: Making the Solar Engine

Just look at the diagram below and create the solar engine that will give power to the symet. After you make the solar engine wrap electrical tape around the LED so it doesnt latch (stopworking) in the light.

Step 5: Applying the Solar Engine to the Motor Body

This step is fairly easy, and all you have to do is connect the left lead on the 3906 transistor to a scratched part on the motor body. See the image below.

Step 6: The Ring

The purpose of the ring is to connect all the positive (+) leads from the capacitors. the circumference of the ring will vary depending on the motor size and shape.

Step 7: Wiring It All Up

Now its time to wire it all up! First off we will connect the right lead from the 3906 transistor to the ring. now get the positive leads from all the capacitors and solder them to the ring. Then we will connect one of the motor wires (doesn't matter which one) to the right transistor lead on the 3904 transistor (the lead where the resistor is connected to the 3904 transistor), and the other motor wire will go to the ring. Now its the solar cells turn! now get the positive wire from the solar cell (dont mix the pos. and neg. up!) and solder it to the ring. Now the neg. solar cell wire will get soldered to the motor body (the scratched part)

Step 8: Your Finished With You BEAM Symet!

After you hotglue the solar cell to the symet you are done with your symet, and all you have to do now is take it outside in the sun or a under a bright light. If your symet is not working please leave a comment below and i will be glad to help you :) ! If you would like to see more simple robots and BEAM robots then please visit my blog at,  and thanks for reading and feel free to comment below :) !