Instructables

Solar Powered Clock Hack

This is a simple hack which will enable your calculator to work on solar power but there is a twist in there we are not going to use photovoltaic cells but we are going to use LED's to build a solar cell. The LED's can not only emit light but sense light and produce a voltage which we will be using to build a solar cell. This is a fun to do project  ,  requires minimal parts and is a low cost project.

This instructable will explain how to create a solar powered calculator , experimenting with LED's to produce voltage , build a solar cell using LED's and how to power devices with it.


 
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Step 1: How Does It Work?

An LED can be used for light detection as well as emission . LED is a simple diode which has been adopted to emit light . Therefore if it is inserted into the circuit the same way as the photodiode it will serve the same function of sensing light.

The LEDs will be sensitive to the light which has the wavelength equal to it or lesser than it.

When a LED detects light it produces a voltage and this voltage we are going to use to power our clock.

I started experimenting with LED's of different colours and here are my results:

BRIGHT LIGHT                                                     AMBIENT    
  
Red LED - 1.3v                                                   Red LED - 0.007v
Green LED - 1.4v                                               Green LED - 0.001v
Blue LED - 0.2v                                                  Blue LED - 0v
IR LED - 0.1v                                                      IR LED - 0.01v
Yellow LED - 1.2v                                               Yellow LED - 0.001v
White LED - 0.003v                                            Whit LED - 0v

From the experiments it is clear that Red ,Green and yellow LED's produce the most voltage so we are going to use one of these three colors.

Step 2: Parts & Tools

Picture of Parts & Tools
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Parts :
~ 10 x LED's (Red , Green , Yellow) - Sparkfun.com
~ A Clock - General Store
~ Some Wires - Local Electronic Store

Tools :
~ Soldering Iron - Sparkfun .com
~ Solder Wire - Sparkfun.com
~ Screwdriver (Optional) - Sparkfun.com
cool idea, not enough people realize this about leds
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