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Re: [TCML] Voltage/power dissapation drop across HV DC current limiting resistors.



You might be able to burn them out with a few ma. I worked in an assembly plant, and the rectifiers we used had a forward current of 3ma and a forward voltage drop of about 50V. PIV was 13kV. If you hooked up a supply of several hundred volts and 5 to 10 mA that should waste the diodes in less than a second. They would then have a voltage drop in both directions of 50V or so. The wire was #39, wound in 16 slots of 300 turns each. That gives a total length of (3 to 4 inches per turn) * 4800 turns = about 600 meters. The current will fry the polyurethane and nylon insulation eventually, but the diodes will burn out in a second or so. I think this is probably a sort of high confidence plan, although I haven't tried it. Best if you have one or two sacrificial units to mess with. Buena suerte.

---Carl




On 9/29/2015 4:01 PM, David Speck wrote:
Matt,

The large majority of potted flyback transformers available these days have integral rectifiers built in, because they were intended for use on CRTs. If they have a long lead with a round anode cap on it, it's safe to assume that it has a rectifier in it.

It's quite hard to find flybacks without rectifiers in them these days, unless you can find very old ones from tube TV sets. Those sets used vacuum tube 1B3 rectifier tubes, 'cause effective solid state rectifiers weren't available at the time.

The old flybacks without rectifiers tend to command high prices when you can find them on eBay.

Removing the rectifiers from an epoxy potted flyback without destroying the hair-fine end of the HV winding is a very difficult proposition.

Dave

On 9/28/2015 11:19 PM, Matthew Sweeney wrote:
This is correct I am building a 'tandem' VDG using both positive and
negative polarities. I picked up two of those HV negative ION generators
just because they were so cheap and I can mess around and see what I get.

I though about picking up some flybacks but they don't say anything about
having a built-in diode and I don't think it's easy to remove them. I
didn't see this deal and already ordered the ion generators, maybe I'll
check these out if the ion generators don't work as expected.

Thanks again for all the info it's been very useful.

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