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MOBILE CHARGER USING SEWING MACHINE BACKGROUND I was walking through a street one late evening when I noticed a new tailor in the corner of the street. He was working under fluorescent lamp making sure his stitches were as fine as they could be. Since I am presently doing a course on electro-mechanical energy conversion, I wondered if it was possible to generate (or convert to be precise) electricity. The mechanical energy available at the machine pulley can be converted into electrical energy without disturbing the regular work of the tailor and also with the minor modification in the existing machine. The energy generated from the day’s work could be stored in batteries and used in the nights (or late evenings) or even to charge mobile phones. This thought prompted me to go further. I thought of ways of generating that ‘energy’. Probably, this could work like bicycle dynamos for lighting. DESIGN OUTLINE
The design of the total setup starts from measuring the speed of machine and the possible INNOVATIVE COMPONENT IN THE DESIGN TEST RESULTS My thoughts went to the lecture of magnetism taught to me by my ninth class teacher. PRINCIPLE:Changing magnetic field around conductor induces current. Now,could this be possible in a sewing machine?Why not?Afterall,that is the principle of a dynamo. We know that changing the magnet field around a conductor will induce current, Now I started to further probe into this. So,the set up: The following would be required - Transducers-alternator, piezo or cyclo dynamos-Rectifiers- to convert ac to dc- Charging circuit - Battery-rechargable batteries-lead acid And if I wanted to use this energy for lighting,then I could also add a lighting circuit. ORIENTATION: Changing magnetic field around the conductor induces current.This can be achieved in two ways: Moving conductor and keeping the magnet stationary Moving the magnet and keeping the conductor stationary When the first case is taken-when a cyclo dynamo is used to move the conductor relative to the magnet: The dynamo can be made to touch the wheel but that will reduce the efficiency of the tailor.This is because the dynamo acts like a mechanical break here.Therefore,maximum cannot be generated An alternative would be to make the magnetic core as a rotor-by attaching it in between shaft and wheel and the conductor around it( which seves as the stator) The sewing machine would look like The energy/output is in the form of a AC.This can be converted to DC with the help of bridge rectifiers.DC current is required to charge mobiles. From the bridge rectifiers,unidirectional current is obtained .For constant current,filters like capacitors are used. Finally from the capacitors the two terminals are given to rechargeable battery.A flow chart would be like CALCULATIONS: 1.Machine pulley 2.Driver wheel -19050097155 Approximate values as per measurement: Diameter of machine pulley= 5'' or 13 cmDiameter of driver wheel=18'' or 46 com (nearly) Assume the maximum speed of driver wheel is 100rpm.So,speed of flywheel would be close to (100x18)/5=360 rpm A rechargable battery-lithium battery(LiAH) is used to store energy.Consider using a battery: OUTPUT:Voltage:3.7V Charge:700mAH capacity Our power target:12W Maximum discharge @ 1 A. Considering the dynamo gives output of 1 W per 3.6V(As per one of the specifications).But close to 14V(for the 12 V lead battery-each lead battery requires 2.3 V and six of them come as a set.So close to 12V to 14V)is required Current i=P/V= 1/14 =.0071=71 mA To charge a 7mAH battery=> 700/71 = 10 hours
If the work timing of tailor is 10 hours=>we need to generate 1-2 W. So a dynamo which can generate about 1-2W is needed (Suppose a lighting circuit is required then,for a 4000mAH battery Current i=P/V= 1/14 =.0071=71 mA To charge a 4AH battery=> 4000/71 = 51 hours
If the work timing of tailor is 10 hours=>we need to generate 5W-6W. We need a dynamo which can generate about 5-6W) A further improvement to increase the energy generated would be to make use of piezo materials.Piezomaterials are those which generate an emf when mechanical stress is applied alternatingly.This piezomaterial could be placed below the machine bed