This is a tiny solar engine based on Solarbotics Miller Engine design found at
Step 1: Part List
x4 1000uf SMT capacitors
x1 Hubsan quadcopter motor
1uf SMT 0603 capacitor
2N3904 / 2N2222 transistor SOT-23
1N4148 SMT diode
2.7v Voltage Detector TC54VC2702ECB713
x1 Solar cell
Step 2: The 1381 Substitute
At last, a SMT equivalent to the 1381 voltage trigger!
The TC54VC2702ECB713 acts in the same way and if you're making micro BEAMs, helps you in shrinking your robots down.
This little engine runs on 4000uf caps, but you can add more for a more powerful output.
Follow the circuit diagram in the introduction.