Bad Mosfet week = new rotor

[Peter Murray]

hi all,

I was getting my cap pulser up and running this week but I kept destroying mosfets. I did get it working, see photo of scope shot.
I am now out of the dark with my knowledge of mosfets and into the shadows.
After the last mosfet was destroyed I decided to start a new enclosed rotor for my 8-coiler. This consists of two disks of HDPE
with 8 slots in each. Bolted together with plastic screws. No more flying magnets. The rotor can have a single magnet with a plastic spacer
Double Norths or super pole configuration.
I have tested it today, it runs quiet, smooth and about 400 extra revs compared to my old rotor (12V - 12V 1800 RPM)
I am now planing a NSNS charging rotor to go with this new rotor.

regards
Peter

[BobZilla]

Hi Peter,
I like that rotor! What is "HDPE" can you elaborate on how you made it?

I just put my super pole back on my machine today. I had not used it for a long time but I decided to give it another whirl.

Here is a pic of both my regular pole and the superpole. They are pretty crudely constructed with gorilla glue but do the job pretty well. In a past life they were the front rollers on a wheelchair. ;-)

[Peter Murray]

Hi BobZilla,

HDPE is High Density Poly Ethylene, this is the stuff they make kitchen cutting boards from. My 8=Coiler is made from HDPE. HDPE does not machine
as nice as some plastics but it is virtually unbreakable and a lot cheaper than acrylic.
I have a combo lathe/milling machine so this is not a problem to machine the slots and get the rotor round and balanced.
The rotor is made from two 30mm thick disks with slots in both disks. These are then mounted on a aluminium hub and 8 plastic screws hold it together.
I can post a drawing if you are interested.

[BobZilla]

Very nice work Peter!

I like that thick shaft you have there too. I have been wanting to make a bigger wheel and use a 1/2 inch shaft that is fixed with the wheel. I purchased the shaft and some nice roller bearings, not wheel bearings but the type that go on assembly line rollers. I thought about using the large wheels from the same junk wheelchair but I have not checked if the shaft will fit. I am also not sure if those wheels are warped to badly to be practical. It has been sitting outside for at least a year now.

Thanks for the offer but I don't need the drawing, I can see how you have done it. Very clever how you made it so you could run super pole or regular poles. I do not have the machinery required to make something like that, sure wish I did.