Ever wanted to make a BEAM robot, but couldn't find a easy circuit to build? Well, meet the FLED solar engine! The robot works by collecting sunlight in the capacitors, then when the voltage is just right the transistors turn on allowing a pulse of electricity, this pulse travels to the FLED (Flashing Light Emitting Diode) which gives the motor a quick turn, then the cycle repeats. The most important part of this project is the FLED which essentially control's most of the electricity generated, so if you use a regular LED the circuit will not work. Now let's get started.
Step 1: Materials
You will need the following materials...
A solar cell with an output of 3vDC (Volts Direct Current)
At least a 1400 uF Capacitor (or more)
A 2.2K ohm resistor 5% (color bands are Red, Red, Red, Gold)
2N 3904 Transistor
2N 3906 Transistor
Motor (make sure it runs on 3Vdc, most do, but just to be sure check with two AA batteries)
FLED (flashing LED)
I got all my components from ripping them out of toys and buying them online. You can try http://www.solarbotics.com/ or http://www.digikey.com or ebay.
you will also need:
a soldering Iron (any cheap one will do)
some solder ( a small/ thin size works great)
a pair of Extra Hands (can buy online or at Radio Shack)
and a sunny location for testing
Step 2: Understanding the Solar Engine
The solar panel creates engery from sunlight, the engery is stored in the Capacitor(s), when there is enough power the transistors allow the current to be released to the FLED, because there is a flashing circuit in the LED the current is controlled and let out in short bursts of engery, the burst of engery travels to the motor, the motor shaft moves and the robot shifts forward. Some of you might be asking what the resistor is for? Its basically there to control the amount of current coming out of the transistors to the FLED (so the FLED wont burn out and die).