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Myke

Mon Feb 26 2007, 02:41AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

If I were to use PVC to wind my secondary should I use white PVC because I hear gray and balck PVC have carbon in it?
Here are the vidios of the flyback driver. I'm assuming that the arcs in the second vid are getting shorter because it is near the end of its life.

uzzors2k

Mon Feb 26 2007, 04:20PM

Registered Member #95 Joined: Thu Feb 09 2006, 04:57PM
Location: Norway
Posts: 1308

White PVC would be best, because of the lack of carbon as you say. Steve Ward has some stuff about making your own flybacks.

A little OT, but make sure you see his HV pendulum.

Shortning of the arcs could be due to mosfet heating, increasing their resistance.

Tonic

Tue Feb 27 2007, 02:52PM

Registered Member #528 Joined: Fri Feb 16 2007, 10:32PM
Location: Warsaw, Poland
Posts: 166

What wire's thickness for secondary wiring would you recommend? I would like this wire to hold a lot of current, let's say, 50mA to 100mA.

Ambar

Mon Mar 19 2007, 09:16PM

Registered Member #549 Joined: Sun Feb 25 2007, 02:49AM
Location:
Posts: 11

I can change the diode of 400V+ of zvs driver, for the diode 1n4148?

Dr. Dark Current

Mon Mar 19 2007, 09:27PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

Tonic wrote ...

What wire's thickness for secondary wiring would you recommend? I would like this wire to hold a lot of current, let's say, 50mA to 100mA.

it does not have to be very thick, I had one flyback that made very powerful arcs and didn't get hot, and it used hair-thin wire for its secondary.
I have used cca. 0.2mm wire for my flybacks with no problem.

Marko

Mon Mar 19 2007, 09:39PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Hi

I had an idea of winding homemade transformers using PVC wire from a while ago, but just wasn't about building a proper form. I would definitely go and wind it 'stacked' style ala solid state MOT's rather than layering like flybacks. I believe it would be a very robust solution for a homemade transformer, it would probebly fail only if seriously overheated or maybe from excessive corona (wich shouldn't be too much of a problem if enough clearance is left between forms and not too much wire is put into each form).

I also feel wire would be better 'heatsinked' if wound that way and not potted.

Pick the wire with thickest insulation you have and make a nice former with proper insulation from core, maybe on a lathe of a single block of plastic.

Myke

Tue Mar 20 2007, 03:15AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

Or just go with the PVC if some people don't have a lathe?

jmartis said that the wire dosn't have to bo too thick and I think it doesn't have to be ethier. I doubt anyone has gone above a couple of amps HV out on a flyback and the single turn voltage shouldn't be that great.

cjk2

Tue Mar 20 2007, 04:31AM

Registered Member #51 Joined: Thu Feb 09 2006, 04:17AM
Location:
Posts: 263

I made a seconday a while back using a piece of 3/4" black pvc as a former. I used packing tape as an insulator between layers, and I did something like 7 layers. I then potted the whole thing in wax. With a ZVS driver and 70 volts in, I got something like 4" sparks out. I used 30AWG wire and had a few hundred turns I think.

Part Scavenger

Sat Mar 24 2007, 03:09AM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

I made one a while back. The inside of trash CD's fits perfectly on the spool, I then made a core of tranparency film, it was very nice.

Also about the sparking between pins, try turning the Screen and (can't remember the other one) Pots down, that usually cuts down on the arcing.

Tonic

Sat Mar 24 2007, 01:40PM

Registered Member #528 Joined: Fri Feb 16 2007, 10:32PM
Location: Warsaw, Poland
Posts: 166

Also I've made two weeks ago an homemade secondary winding. I've used ~0.4mm thick wire and half-transparent foil I bought in garden shop. If I remember correctly, I did made 5-6 layers, each has something around 65 coils, so, overall number of them would be like 325-390, giving ratio from 1: 32.5 to 1:39. I don't know if I calculate correctly, but with 40V input at load the output is equal to 1.3-1.5kV. Arc ignities at 2-4mm distance and stretchs to 6-7cm. It may not look great, but the current is horrible! Arc is very bright, enough to make me thinking about welding goggles. Even this arc melts steel.

And the conclusion is that I need to increase ratio in order to obtain higher output voltage and decrease output current. Well, the good thing about selfmade secondaries is that you can made in way that prevents from breaking high voltage insulation. The good idea would be buying big and tall U ferrite core, but it's hard to find and the prices ain't sound funny. (Two pieces of U100 cores costs in my town about 20 euros).

What do you think about painting coils?

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