Al's Robotics....

Variable voltage firing solar engine.

I've recently been carrying out some experiments on getting the voltage firing level of a solar engine higher and here's what I've come up with. So on this page you will find out how you can make one for a BEAM robot powered by a SE (solar engine).

The idea is simple and there's no need to use a voltage trigger either. Now where you normally have a flashing LED in the a FLED engine, in this one you have standard power diodes. A diode has a voltage drop of some were in between 0.5 to 0.7 volts so the more diodes that are put into the circuit in series pushes the voltage firing level up, this enables you to have a higher voltage output to your motor. A normal FLED engine fires around 2V but with this circuit you can make it fire from around 0.6V up to what ever you want, with enough diodes put in series it could be made to fire at 12V and if you don't want to use loads of diodes you can use zener diodes instead with the appropriate voltage ratting on.

Below are some of the results I found when caring out my circuit design.

These figures are approximate.

The circuit.

This circuit fires around 3V, but depending on your needs change the diodes to get a lower or grater voltage firing point and maybe try adding on the flashing LED to get a 2V drop plus the amount of diodes for a voltage drop of about 0.6V per diode.

Components that can be used
D1, D2, D3, D4 and D5 are 1N4001 diodes (but you can use 1N4002, 1N4003, 1N4004, 1N4148 etc.).

NPN transistor can be any small NPN transistor i.e. 2N2222, 2N3904, ZTX304 etc.

PNP transistor can be any small PNP transistor i.e. BC121L, ZTX500, 2N3906 etc.

Capacitor can from 1000uF to 4700uF (note that a small capacitor means faster pluses at a lower power).

Solar cell that should be able to give out 2V in a circuit in my opinion.

Efficient solar motor.

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