Solar Engine

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Please improve this article if you can. (June 2006)
For other meanings of "solar engine", see solar engine.

A Solar Engine (also called solarengine and SE) is a simple BEAM circuit which receives radiant energy, capacitates and stores the energy, and then utilizes that energy in pulses to power motors or other loads. Solar engines are electrical engines powered by solar cells. Solar engines are composed of relaxation oscillators.

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[edit] Description

Solar engines behave as a power bank. Solar engines charge gradually and then discharged rapidly (to power a load). Incoming energy is stored up until a usable amount is in reserve and then released suddenly, performing (periodic and incremental) work. Solar engines usually have a resistor, a capacitor, and some sort of "threshold" device. The solar engine advantages include:

  • workable in relatively-low light levels
  • minimal solar cell size

Characteristics of the engine include:

  • economical,
  • efficient, and
  • ruggedized expansions

Solar engines which have been constructed heretofore have not generated large quantities of electricity. Arrays of cells can be used to attain more power (though as the number of cells increase, the frame [and its associated weight] is increased; frames are usually made as lightweight as possible to increase speed).

[edit] Forms

All links in this section are to Solarbotics.net, a free BEAM community site.

[edit] Voltage controlled trigger

The predominant form of solar engine.

  • Zener-based : A capacitor charges until a 2N3906 transistor (PNP) is signaled by a Zener diode and turns on. Then a 2N3904 transistor (NPN) turns on and the capacitor is discharged through the motor. As the 2N3904 transistor turns on, a 2.2 kilohm resistor starts to supply base current to the 2N3906 transistor and the circuit is activated. When the capacitor voltage drops below about one volt, the 2N3906 transistor turns off, the 2N3904 transistor turns off, and the motor deactivates and the process is repeated.
  • FLED-based : When a FLED flashes (around two and a half volts), it conducts and makes the 2N3906 transistor (PNP) signal a 2N3904 transistor (NPN) which, in turn, supplies current to a motor. When the NPN transistor triggers, the FLED is essentially out of the circuit. When the voltage drops to around one-half volt, the transistors idles and the process is repeated.
  • 1381-based : As a solar cell charges a capacitor and the voltage rises to the 1381's trigger voltage, the 1381 voltage trigger IC signals a 2N3904 transistor. The 2N3904 transistor signals a 2N3906 Transistor, which, in turn, supplies current to the base of the 2N3904 transistor. The current then activates a motor. When the voltage drops to around one-half volt, the transistors idle and the process is repeated.
  • FRED SE ("Mazibug")
  • The "Miller engine"
  • GBSE ("Gate Boost Solar Engine")
  • "MicroPower"
  • VTSE ("Variable Threshold Solar Engine")
  • DSSSE ("dual slope-sampling SE")
  • "Chloroplast"
  • Vx2SE ("voltage-doubling solar engine")

[edit] Time controlled trigger

Less efficient, but activated at specific times.

  • HBS ("Happy Birthday Singer" greeting card) chip
  • 555 chip

[edit] Charge curve differentiated

Theoretically most efficient.

  • T3SE "Type 3 SE" by Wilf Rigter
  • Tritium by Ben Hitchcock

[edit] Nocturnal

Charges during light exposure and discharge when dark.

[edit] External links