BEAM Online - The Yahoo of BEAM!

- 1381 Solar Engine -

Note: All of the circuits on this page are for Personal use only. Commercial usage is prohibited unless arrangements are made with the patent holder Mark W. Tilden
Jump to:
This is the most common SE because it's fairly easy to build and is fairly efficient. Well the most common use is in a solaroller which is a small wheeled car that charges up and then moves in a quick burst of speed. Since you can only use motors and coils with this circuit robots built with this circuit are mainly mechanical such as my artistic butterflies. One other common use is a little thing called a symet which can roam around and not get stuck using only one motor.
Where to get
Part #
3v+ Solar cell 1 Solarbotics See products page
Motor 1 Broken electronics - walkman, cd player, pager.... Or new at: Solarbotics BG Micro All Electronics Goldmine Electronics

See products page Browse catalog Browse catalog Browse catalog
2.2K Resistor 1 Solarbotics Digikey See products page 2.2KEBK-ND
2N3904 Transistor 1 Solarbotics Digikey See products page 2N3904-ND
2N3906 Transistor 1 Solarbotics Digikey See products page 2N3906-ND
??? Capacitor (see Circuit notes) 1 Solarbotics Digikey See products page See FAQ page for some sizes
1381 J Voltage Detector 1 Solarbotics DigiKey See products page MN1381-J-ND
Choosing the right size capacitor First you need to think about what your application is. Do you want the motor to spin for a long time or just a a few turns? If you want it to spin for a long time then your going to need a bigger capacitor. I mean bigger in capacitance not physical size. If you want it to spin for only a quick second then a smaller capacitor is what you want. Here's the catch. The bigger the capacitor you have the longer it will take to charge up and move. So a 2200uF (.0022 F) capacitor might take only a second to charge but a 1F capacitor could take 8 minutes. Unless you have some specific project I wouldn't go any smaller than 3300uF. Here's a few sizes I commonly use Dual SE photovore - 3300uF Solaroller - around .033F About 3 - 4 minute charge - .33F On the freeform layout The easy method is exactly the way it is shown. In the harder method the pins are facing up and of coarse you'll need to stick the cap and solar cell somewhere. 1. The solar cell starts charging the capacitor and the voltage rises
2. As soon as the capacitor reaches around 2.7v the 1381 turns pin 1 high and turns the 3904 ON
3. When the 3904 turns on it brings the base of the 3906 low which turns it ON
4. With the 3906 ON current is supplied to the base of the 3904 which keeps it ON
5. Now current can flow through the motor and it turns
6. When the voltage gets down to .7v the transistors turn OFF and the process is repeated 2N3904
Yep, click here.

Copyright © 2006 Solarbotics Ltd.
For problems concerning this site please contact the Webmaster.
Nervous nets copyright and patented by Mark Tilden. Content originally developed by Ian Bernstein.