TOPIC:

steell wrote:

gearheadmm wrote:

steell wrote: I'm not sure it is possible to generate DC, I believe all generators/alternators generate AC, but that is then converted to DC in some situations.

Think about it, in every case you have a copper wire rotating through a magnetic field, so the voltage starts at zero, increases as the wire approaches the field, reaches peak in the middle, then decreases as it exits the field. And that's the definition of AC. In some generators a commentator is used to convert the AC to DC.

EDITTrue but DC generators output is on the positive side only,
And AC alternators output is on the positive and negative side of a sign wave.
That's the difference. Generators are rectified by inherent design and alternators need some additional means of rectification.

The current generated in the armature is AC - not DC. To get it converted to DC so it can charge your batter and run your headlights, a device called a commutator is used to "rectify" this situation. It is on the armature and has a series of contacts along it's outer surface. Two spring-loaded brushes slide on the commutator - one brush is connected to ground and the other is connected to the main output of the generator. As the armature and commutator assembly rotates, the brushes come touch the different contacts on the commutator such that the polarity of the current moving in the armature is always connected to the correct brushes. The net effect of this is that the generator output is always DC even though the current inside the armature windings is always AC.
www.rowand.net/Shop/Tech/AlternatorGeneratorTheory.htm

No, take the back off any automotive generator (Old pre alternator) and you'll see two brushes, one connects to ground while the other connects to positive. And if you take a look at the generator armature using a ohm meter you will discover that every contact on the commutator is connected to another contact 180 degrees away. Hmm, I need to think about this some more, you may be right.

Edit:
Ok, I'v cooked and consumed my steak (had a T-Bone instead of my usual rib eye) and am still enjoying my drink, and I've thought it over, and I've figured out I don't even understand your statement.

Got to have a positive and negative to make a complete circuit. On a generator the positive side of the wave is connected to the positive terminal, and due to the mechanical location of the contacts on the commutator, the negative side of the wave is connected to the negative terminal. A mechanical rectifier.

I am going to become increasingly incoherent as the night goes on, and I'll be enjoying every bit of it

And yes, gen output is a pulsing DC.
On a KZ the brushless alt supplys three phases to an external rectifier/regulator.

When you remove the average DC component from a switched DC source, what you have left is AC.

It's just a matter of semantics at that point. Anything, regardless if it is "only on the positive side", still has AC if you break the signal down to its components... which is what we do when we apply the math equations to it. Any repeating waveform, as long as it is not pure DC, is composed of sine waves added together.

It should be said that there is no generator that produces pure DC current, or only DC current... without rectifying, filtering, regulating, etc. And by generator, we should say a device converting mechanical energy into electrical energy by changing the magnetic flux through a loop of conductor.

as long as we're talking about AC and inductors... here's a video I put together a little while ago showing how to select/adjust inductors to get an ideal rotating field for an induction motor.