DIY Alternator - Wiring
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This is where the alternator really takes shape. The stator exists to provide a place to put loops of wire that covert the changing magnet field of the spinning rotor into electric current. In all, the alternator uses nine loops of wire. Unfortunately, not any type of wire will work. The wire needs to be coated so that it does not conduct between turns. For this, you need magnet wire, which is unfortunately somewhat difficult to find. In my experience, ebay was the best place to buy wire. About 150m (~500ft) of the stuff should be enough. I used 20 AWG size wire, which worked well. Each loop had 55 turns, and was looped counter-clockwise. It doesn't matter which direction you loop the wire, but it should be consistent between all the loops. (i.e. they should all be clockwise, or all be counter-clockwise.) When winding, keep the loops tight to the stator. It's also best to get the loops as close to the magnets as possible. That will increase the current the alternator produces.

Another view of a loop. After finishing the loop, I liked to tape together the strands. This gave the loops a little more stability, and kept any stray wires from hitting the magnets. Make sure you keep extra lengths of wire at the begging and the end of the loop.

Wiring takes some time!

All of the wire loops in place.

All of the wire ends going every where should look a bit like a mess right now, but they are important to keep straight. This alternator is designed to be three-phase, which means that specific loops of wire will need to be soldered to specific other loops. Essentially, there are three groups of coils, with three coils per group. In the diagram below, they are labled by number and color. Each coil should be two coils away from another coil on the same phase. This is where the extra lengths of wire come into play. Select one loop as the starting loop. This will be a loop in phase 1. Take the the wire on the top side of the loop (the left over wire from the last turn of the coil, and the part of the loop that is furthest away from the magnets) and label it as "-1". Then take excess wire from the bottom side of the loop and solder it to the top wire from the next coil clockwise from in the same phase. Then, take the bottom wire from that coil and solder it to the top wire from the third coil in phase 1. Finally, take the bottom wire from the last phase 1 coil and label it as "+1". Repeat this same process for phases 2 and 3. 

Labeling the phases.

Soldering the wires together. This is a great time to test your wiring work with a volt meter. Connect one probe to the negative wire of a phase and the other to the positive wire and give the alternator a spin. If there is no voltage, then there's a problem. Remember, though! This is AC current, so if your voltmeter doesn't have a AC mode, you won't see anything.

The leads from the alternator will end up here, which is a box with three bridge rectifiers, which are basically fancy diodes. They can take 3-phase AC current and output DC current. On each bridge rectifier, there is a pin for positive, negative, and two wires that are the+ and - of the AC source.

This is how the bridge rectifiers should be wired. I broke up the bridge rectifiers into the diode level of complexity so those that are familiar with circuitry can see how they work.

The bridge rectifiers partially set up.

The finished bridge rectifier box. The black and red wires coming off of the box are the overall DC - and + wires.

The finished Alternator.

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