AC TO DC???

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TannerOates
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AC TO DC???

Post by TannerOates »

I have a franceformer (15kv) sign transformer and I would like to know the simplest way to make the output -15DC instead of AC thanks.
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Chris Bradley
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Re: AC TO DC???

Post by Chris Bradley »

TannerOates wrote:
> I have a franceformer (15kv) sign transformer and I would like to know the simplest way to make the output -15DC instead of AC thanks.
Those French, they always do things slightly differently! So it might be difficult to tell!

The best way to get pure DC is to tie the transformer to a long rope wrapped around the spindle of a DC dynamo attached to the side of a tall building at the top, and then drop the transformer.

...or you could just use *a diode* (connected to the electrical parts).

Alternatively, just don't bother as a fusor will act somewhat as a thermionic rectifying diode anyway so you could try that first.

Better still, read the forum as this is a question sooo well addressed here that it is difficult to see how you arrived at needing to answer that question.
George Schmermund
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Re: AC TO DC???

Post by George Schmermund »

Chris - Your suggestion for getting DC from an AC transformer reminds me of the method of determining the height of a building using a barometer. Carry the barometer up to the roof and toss it off. Then time how long it takes to hit the pavement.
Anything obvious in high vacuum is probably wrong.
Hector
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Re: AC TO DC???

Post by Hector »

I personally would use a Bridge rectifier. Now this may have to be very sturdy depending on the size and power of the transformer. You're going to have to size the rectifier correctly for the transformer power and voltage. If you want to smooth the DC you'll need a filter capacitor and that could get very big depending on the load. If you want to raise the voltage even higher then my choice would be to make a Cockcroft Walton Multiplier to rectify and multiply the voltage at the same time.

The people on this board can help you, but they need to know a lot more about your Transformer.

Good luck.
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Carl Willis
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Re: AC TO DC???

Post by Carl Willis »

I personally would NOT use a bridge rectifier.

In the usual fusor configuration with a grounded anode/chamber, one cannot connect the positive terminal of the bridge to the chamber. If you do use a bridge rectifier in this way, you'll be shorting one half of the transformer secondary. It's worth remembering that NSTs are center-tap grounded.

There are FAQs and many examples of NST-based power supplies to be found in the archives.

-Carl
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Richard Hull
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Re: AC TO DC???

Post by Richard Hull »

Carl is correct. Look in the archived material.

Ground the transformer case, (center tap)
Connect two diodes of the proper voltage rating such that a cathode of each diode goes to each insulator knob and the anodes are connected together. This anode connection is the hot, negative, HV point and the case ground is positive. A capacitor of the proper rating can act as a filter.

Richard Hull
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Jerry Biehler
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Re: AC TO DC???

Post by Jerry Biehler »

No, no. Everyone knows the proper answer is going to the basement and telling the Maintenance guy "I'll give you this nice barometer if you tell me how hight the building is"

-Jerry
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Re: AC TO DC???

Post by AFW »

The various methods for using a barometer to measure the height of a tall building were given as an answer in a Physics exam by a Danish student called Niels Bohr
Tony
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