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).

Step 3: Putting It All Together

I found out that it is a lot easier if you follow the pictures, like you would on a jig saw puzzle. In the same way you to can "connect the components" by looking at the picture.

NOTE: IT IS IMPORANT TO KEEP THE POLARITY! ALL LEDS (THAT INCLUDES THE FLED) ARE POLARITY SENSITIVE! SO ARE CAPACITORS!

Polarity Rules for FLED, LED's, and Capacitors

- Capacitors have a line on their side that is a different color that the other more dominant color, this is the negative. Ex: a Capacitor is blue all over except a black line, that would be the negative.

-FLED's and LED's have a flat side around the bottom of their base, this is the positive lead. Ex: a green FLED has a circular base and a flat side near one of its leads, this is the positive lead.

Once you have followed the diagram below and have soldered everything up it is now to test or troubleshoot the Solar Engine.

Step 4: Testing and Troubleshooting

Ok time to test it out. take a marker and mark a spot on the shaft of the motor, anywhere will do but just make a dot. Now put the solar engine in some sunlight and if the shaft moves you should see that dot move. if it works, you have created a Solar Engine. If it doenst move for about 6 minuites its time to troubleshoot.

Here are some common mistakes:

bare wires touching
bare wires touching metal that touches other bare wires
to big of a capacitor, and taking to long to charge
not enough power comming from solar panel
broken motor
any broken/ really dammaged component
wrong components