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Note 1: Correction regarding stated operating speed. In the video I mentioned a nominal operating rotational speed of about 35 RPM. This is very wrong. What was meant was an oscilloscope waveform reading of 33-35 Hz, which translates to a mechanical rotor speed of 660-700 RPM. Note 2: Apologies for the abrupt ending of the video, which resulted from running out of storage space on the camera's SD memory card. Many of the materials for this project were recycled from previous projects of a similar nature. In particular the magnets and copper wire were all taken from previously made coils and stators. Additional magnets had to be purchased, as did the hollow steel cores for the new coils, which had to be rewound from previous larger spools unto the new ones. The rotor consists of a 3" ABS coupling with an outer diameter of 4". This is filled with short-strand fiberglass auto-body filler and then drilled with 11/16" holes which accept the magnet stacks. The magnets are neodymium discs in stacks of 5, but the holes were drilled deep enough to accept one more layer of magnets and hence is "upgradable" in a sense. The rotor shaft is 5/8" threaded rod, and the shaft alignment is achieved by fitting 3.5" dia. aluminum pulleys on each end of the rotor, each pulley having a 5/8" center hole. The rotor housing consists of two 4" PVC couplings with an inner diameter of 4 1/4" so that the rotor fits inside with a 1/8" clearance around the perimeter. This, plus the 1/8" thickness of the outer coupling creates a 1/4" gap distance between the magnet stacks and the coil cores, which is a bit too wide for optimum performance but could be slightly reduced by adding an additional layer of magnets and allowing them to extend partway outside the rotor cylinder. The rotor housing is completed by an idler pulley at each end, which provides the 5/8" bearings in which the shaft rotates. The stator rings are cut from 3/4" plywood, 14.5" outer diameter and 3/4" thick. The coil tension adjusters are simply carriage bolts (1/4" x 3.5") with two nuts and a washer, which allows for tightening the coils inward against the rotor housing. The rotor housing support and gear-drive support structures are made of 3/4" plywood also. The coils are wound onto cores made of 3/4" galvanized adapters which are fluted at the narrow (13/16") end and threaded at the wide (1") end. The narrow end is fitted with a section of 5/8" wooden dowel with a 1/4" hole drilled down the center to accept the carriage bolt of the tension adjuster. The coils are wound with approx. 500 turns of 21 gauge copper magnet wire. Each stator is fitted with nine coils, wired in a three-phase arrangement, in this case Y-configuration which leaves three output (AC) ends and three opposite ends which are twisted together to form a common "floating" point. The three output ends are attached to a 6-diode rectifier bridge to produce DC voltage and DC current. The dual stator arrangement results in a total of 18 coils and two separate diode bridges which are then connected in parallel to double the current output of the device. Final output is tapped from the POS/NEG leads of only one bridge. At moderate cranking speed of about 650-700 RPM (achieved with a 1:4 gear ratio) the output under conditions of no-load is approx 35 V and 1.3 A (1300 mA). Under conditions of load the voltage and current vary with the nature of the load resistance, but in the case of a 12V battery being charged, there is a steady 900-1000 mA of available charging current.
