High Speed Alternator

[WXYZCIENCE]

Made from an old 4" Sony VTR head that has been begging to be put back in service. I did some drawing on the cad program and discovered that six 1x1x.5 inch N48 neos fit perfectly.







There is a machined 1/4" steel backing plate added behind the magnets. The plate also builds up the height flush with the top ring. A close up shows the spacing between the magnet corners.







No machining of the head had to be done so the initial balance was retained. My first tests on this setup at 7200 rpm ran smooth as glass. I will do some coil design tests with the head this weekend and post the results. This last picture is a side view and the head spinning.







Now to wind some triangular coils.
Joseph.

[ghurd]

I shall ask first.  What the heck is a 'Sony VTR'?

Nothing like any VCR I ever opened.

G-

[TomW]

Video Tape Recorder? It just fits ...

[Ungrounded Lightning Rod]

You should cut the backing ring down to just over half the height of the magnets, or use something non-magnetic like stainless or aluminum.  Otherwise you'll be shorting out much of the magnetic field on the outer portion of each magnet - where the speed is highest and you'll get the most use from the field.

[ghurd]

But every VHS machine I ever opened had smaller guts.

Like only for lighting LED sized guts.

Maybe AA charger guts, but still real small small stuff.

[tecker]

Agreed

[tecker]

That's my focus in scaling down the dual rotor is to make some unit to operate in the range of 10 to 3k rpm.This will be fun

[WXYZCIENCE]

Tom is correct. Old dinosaurus! Seventy-five pounds of video recording high quality BETA.

They had one inch tape and made a whistling, whirring, clucking sound. Better that they gave up the ghost.


The new alternator will use some of the truly recycled dinosaur bones.
Joseph.

[WXYZCIENCE]

ULR, I agree that if it was made of steel it would short out the flux lines but the hub is made of aluminium. Thanks for the comment.
Joseph.

[Ungrounded Lightning Rod]

Oh, I see.  When you said "steel backing plate" you were talking about the "big washer" under the magnets, not the wall around them.  Sorry I got confused.

Yeah, Aluminum's great for this job.  Doesn't short out the field (and in fact any eddy currents are the result of it holding the field in place as the magnet goes past the coils, experiencing varying "drag", i.e. induced back currents from the fields generated by the current in the coils.)

[Norm]

Yeah...and you had to have a formatted tape

just plain vhs tape didn't work

[willib]

amazing how junk fits together , isnt it

i was extremely lucky to use/find the three sprocketed sprocket that i used on the flywheel of the  Exergen, i'm not sure if it would have worked as well without it.

[wooferhound]

I made a genny using almost the same design but it was 9 inches in diameter.

http://www.fieldlines.com/story/2004/4/4/164552/3003

I tried to make the coils Triangular so that two magnets would share the same coil giving a North over one leg and a South over the other leg. This seems to work really well with minimal cogging.

http://www.fieldlines.com/story/2003/12/7/225257/916