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Registered Member #3343
Joined: Thu Oct 21 2010, 04:06PM
Location: Toronto
Posts: 311
Ash:
The above pulse trafo works at 0.3 T, 2microsecond pulse, without problems .... Maybe 10% of voltage impedance, that is not a concern at the time. I think it is time for you begining set up yours tools and jigs...
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
I've a 'work in progress' drawing, if anyone is interested. It's certainly not a 'full working drawing' yet, but it has six pancake coils, 5mm of polystyrene as insulation for 50kV, and I think I can still improve it further. I still have quite a bit of space to play with.
At the moment, theoretical output is 48960 volts @138 milli-amps.
It has 2 one turn and 5 two turn primaries. I'm trying to minimise leakage inductance as this will be driving a multiplier, but I think stray capacitance will be pretty minimal as well.
Registered Member #3700
Joined: Sat Feb 19 2011, 12:59PM
Location:
Posts: 107
Hi Ash,
Very impressive, the tx is taking shape!
Why you do not wind just one pancake and post the pictures? The purpose is figureout the insulation/wire arrangement ( and the mechanical stability of the pancake).
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Tony Matt wrote ...
Why you do not wind just one pancake and post the pictures? The purpose is figureout the insulation/wire arrangement ( and the mechanical stability of the pancake).
Several reasons. Firstly, I now need to find another source for the polystyrene for the inter-winding insulation and main bobbin core.
I can use CD cases for the insulation between primaries and secondaries, etc (the flat sheets).
Now that I know what sizes I need, I can obtain some more 'samples'from the polystyrene container suppliers, etc.
I may have to wait until I have my lathe here before I can shape the formers for the inter-layer insulation. I won't have my lathe here until Easter at the earliest (it is currently in storage 200 miles away). I'm still getting my workshop here set up. There are a few local engineering shops that I could get to turn the formers, but I'd sooner spend what money I have on getting my lathe, etc. installed in my new workshop.
I think thermo-plastic bobbins/inter layer insulation is the way to go here, as it is self supporting and easy to shape. My only concern is vibration, which could lead to broken wires if I'm not careful. (And keeping the temperature below the glass transition temp.)
Also, just winding one pancake secondary won't tell me a lot about total leakage inductance/stray capacitance. I really need to wind the whole thing. It will tell me if it is possible to use this method for winding the pancakes, though.
EDIT: I could try winding a smaller version, as I have a few polystyrene tubes lying around that are too small to use for the transformer itself, but I'd still need formers to shape the inter-layer insulation. I may just wait until I'm able to build the full sized version.
EDIT: I could try building one using seamed tube made from CD cases wrapped around a former and glued using polystyrene cement. If I stagger the seams it shouldn't adversely affect the insulation by any significant amount. It shouldn't really be any more difficult than building an Airfix kit.
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Calculating self-resonant frequency of HV Transformer?
