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Freeform 1381 Solar Engine
This tutorial will have you building your own freeform solar engine in very little time. 1381 SE's can be used in solar rollers, symets, aquabots, photovores, magbots or anything else you can come up with. Although this is a good first circuit, it is recommended that you at least have some experience with your soldering iron before you start.

Parts List:
1381 voltage trigger
2N3906 transistor
2N3904 transistor
2.2K resistor

Tools Required:
Soldering Iron
Wire snippers

1.

First bend and solder together the emitter of the 3906 transistor and the 2 pin of the 1381 as shown. As always, clip extra wire leads. Black dots indicate new solder joints.

2.

Then bend and connect the 3906 collector with the 1381 1 pin as shown.

3.

Solder the 2.2K resistor to the 3906 as shown.

4.

Now connect the 3904 to the rest of the circuit as shown.

5.

This final step puts the SE into action. Connect a solar cell, capacitor and a motor as shown. The cap should be at least 2200 uF, the solar cell at least 3 volts and the motor efficent.