Stupid questions??

[Fiddlehead44]

As I understand it, a generator or alternator produces

AC electricity and this is converted to Dc by bridge

rectifiers.If this is so..

Question 1. How was this conversion accomplished before

the invention of diodes and bridge rectifiers. Such as

in a 1940's car.

Question2. A car alternator does not have a place to dump

excess electricity when the battery gets full, it simply

stops charging and starts freewheeling. Why can't a

wind genny do this?

Question 3. Could an old type car voltage regulator with 3

sets if points in it be used in wind energy controls?

Question 4. What was a magneto? (on old engines)

                           Fiddlehead44

[Opera House]

A good comparison is driving down the road with a manual transmission.  All at once you step on the clutch leaving the gas at the same position.  What do you think happens?  Same thing happens with a wind genny.  In solar systems many regulators "disconnect" from the battery, wind regulators shunt the power to somewhere else.  In the old days there was rotary rectification.  That was the purpose of the brushes and the commutator.

[ghurd]

A very simple explaination, the best I can do...

A magneto is a higher voltage, lower amperage, alterator.

The volts are controlled by the battery absorbing the power.

They are low efficiency, so the battery almost can't overcharge.

Good for powering the spark plugs, because the power made is needed for the spark plugs. Higer RPM means more power made, and more sparks (power) needed per minute. It kind of balances out. Great for chainsaws, weedeaters and dirt bikes.

Not very good for battery charging.

G-

[drdongle]

Generators produce DC, alternators produce DC, 1940's cars used generators, no rectifiers needed.

Free wheeling can result in the destruction of a wind turbine. ( flying apart)

An old style auto regulator would be unable to control a wind turbine, as they are designed to regulate a generators field current. Most turbines in use here have no field winding to control.

[drdongle]

Correction, Alternators produce AC.

[wpowokal]

Before diodes wind turbines used selenium rectifiers developed by Dunlite in Australia if I understand correct, here is a link to what one looked like just scroll down the pics.

http://www.theodoregray.com/PeriodicTable/Elements/034/index.s7.html

allan down under

[terry5732]

Before diodes there were vacuum tube rectifiers for home devices requiring DC. But the vehicles produced DC via generators as noted above. You could put a generator on a windmill but the brush maintainance etc just isn't worthwhile.

Although a magneto may be producing 25,000 volts , it is of little power. In some applications , the mags are oversized and you may be able to steal a little off them. In most motors though, the mags are sized so that if you draw any you will have trouble with inadequate spark.

Remember how your voltage regulator failed 3 times as often as your alternator? They aren't very heavy duty and certainly wouldn't be suitable for a genny with good output. But maybe you could make a heavy one.........

[wpowokal]

Terry with respect I must disagree about using generators as wind turbines. yes brush maitenance is a concideration but like every year.

Most compound wound generators increase their field as output increases, as oposed to perminate magnet generator whoes field is fixed by magnet strength.

Then again I'm from the old school, now where was that rock I crawl under.

Having said that I would use a Pm generator over all others, guess I know both worlds.

allan down under

[Clifford]

It turns out, the Model T Ford used an Alternator rather than a generator, and ran on AC Current (not rectified).  It was a permanent magnet alternator running on disks (the flywheel), not too unlike the PM Wind Alternators that are being made such as the "Volvo Disk Brake Generator".

The early Model T's didn't have batteries, and thus AC worked fine.

Only later was a separate generator added allowing for a battery and electric start, electric lights, and regulated voltage.  However, I believe that the ignition remained AC.

I'd have to look at Magneto design, but I wonder if they are a fancy name for Permanent Magnet Alternators (often with the distributer as part of the same unit).

---- Clifford -----

[redeyecow]

 

  Hi,  I have a couple of old tractors with magnetos for spark. They are set up for crank starting by having a spring loaded armature (PM). It holds the magneto until one

of the cylinders hits the top of the compression stroke. Then it snaps around as the spark points open. It's great because you can just crank it slow and still get a really

good spark.  It saves broken arms and windmill cranking. Thought I better mention wind.

    Keith