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Home made perpetual LED torch.... |
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The torch described here is a perpetual one. Not in that sense where output is claimed to be more than input! It does not need any batteries to power up. It works on the energy generated by shaking the torch for a minute or so. A strong magnet is allowed to move freely to and fro inside a tube. The tube has a coil of wire wound in the center from outside. There are two small but strong magnets at both ends of the tube so that the middle magnet, which moves to and fro, does not hit the ends and breaks into pieces. The North–South orientation of these small magnets is such that these both tend to repel the middle magnet when it comes closer. You will get the idea of its construction from the sketch below. Now, let us see the details. |
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The copper wire used is of 34 SWG, enameled. Number of turns have not been counted, but the entire spool of 30 mm length, 20 mm inner diameter, and 30 mm outer diameter has been filled completely. Resistance of the coil turned out to be around 130 Ohms. The magnet which moves in the middle is of Rare Earth type and is cylindrical in shape with diameter of about 20 mm. Length is about 30 mm. The two magnets at the ends are also of Rare Earth type and cylinders with 10 mm diameter and 15 mm length. |
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The body is made from Polypropelene rod and made in four pieces.. The main body, front portion where LED and lens are fixed, A ring where magnet is inserted for making the reed switch ON and OFF. These are turned on a lathe machine. Front portion is made of two pieces and a ring ( seen yellow in the photograph below ) is slided before sticking two together by adhesive. The yellow ring is able to turn or rotate about the axis of the torch, by about 30 degrees. A rectangular magnet embedded in the ring, like a key in the key-way on shafts of motors, makes a reed switch below it ON or OFF. This arrangement makes the complete torch water proof. The switch can never come in contact with outside environment. A heat shrink type PVC sleeve used for covering Electrical Bus Bars, has been shrunk fitted over the body. These are available in bright Blue, Red and Yellow colours. This is seen as a yellow tube in the photgraph. |
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Energy Storage: A super capacitor of 5 farad value, 5.5 volts, is used for storing the energy generated. This is enough to glow Ultra Bright LED for quite some time. The graph on the left hand side shows how the intensity gradually reduces with time. Figures on the X-axis are of seconds. A current of even
10 mA is sufficient to produce bright light. |
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