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

Paula,
MOTs are going in the wrong direction for this project. They have relatively low output voltages, but very high output currents. A good MOT can easily put out 500 mA into a short circuit, as they have only a very small built in leakage inductance.
You don't usually begin to see corona at less than 10 KV, so even doubling a 2200 volt MOT would only give you 4400 volts, and the amount of stored energy plus the high current capacity of the MOT would result in a system with a much greater lethal potential than a rectified NST.
Matt's project is looking for a moderately high voltage at a very small current.
I'm not sure how wide his belt is, or how efficient his corona generating electrode is, but a milliamp or less at relative low voltage would probably be entirely sufficient for his purposes. 

Dave

On 9/28/2015 8:40 PM, Paula Lange wrote:

What about two microwave oven transformers with diodes and Voltage doubling capacitors? That would give you plus and minus 4kv.

msweeney23@xxxxxxxxx wrote:


I wish i could but i need both DC polarities :(

I know an NST is totally overkill for this but outside of using an old fkyback without the built in diode i dont see many options.

Some 20 years ago i built this using a flyback from an old tube TV running on 12DC but it was just a curiosity and i scrapped it when building my first TC (at age 17 with no real knowledge building plate glass capacitors - lucky i didnt kill myself).

If i could find a cheap +/- HV DC generator id be happy. Could i use a single polarity and somehow shift it down so i see a +/- half the voltage?

----- Reply message -----
From: "David Speck" <Dave@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Subject: [TCML] Voltage/power dissapation drop across HV DC current limiting resistors.
Date: Mon, Sep 28, 2015 11:53 AM

Matt,

In today's eMail I received an offer from Goldmine Electronics for a 15
KV negative ion generator that runs off 12 VDC for $10.  It's
intrinsically current limited, and you can lift it with two fingers
instead of two men and a boy like your NST corona generator.

If the polarity is right for your application, then it would be a simple
way to go.  Special sale price ends 9/30.  (No connection to seller, but
a frequent buyer).

http://www.goldmine-elec-products.com/prodinfo.asp?number=G20855

Dave

On 9/27/2015 9:51 PM, Matthew Sweeney wrote:

No that is exactly correct. Another user mentioned that I should be careful
using NST for VDG seemingly because there could be short down in the inside
of the VDG to the HV brush, allowing potentially lethal currents up to the
collector. I've not been able to confirm this exact reason - maybe someone
else can chime in on this.

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