# Building a transformer.

1. May 23, 2005

### RGClark

For my project I need to transform the power from a 3000 watt, 120V AC generator to a high voltage DC, say 30,000V DC.
Are such transformers easily made or of low cost?

Bob Clark

2. May 23, 2005

### Cliff_J

3. May 23, 2005

### Dngrsone

Monitors and televisions also have transformers that develop voltage in that scale ~15-35KVdc

4. May 23, 2005

### RGClark

Thanks. But could they handle high wattage like 3000 watts?

Bob Clark

5. May 23, 2005

### RGClark

This looks like it's only for creating long sparks. I want to generate continuous high voltage DC.

Bob Clark

6. May 23, 2005

### Staff: Mentor

You want 3000w output? You'll lose an enormous amount of energy in the conversion (I think). What are you trying to do this for?

7. May 23, 2005

### RGClark

Yes I want 3000 watts in the output. If I lose some amount in the conversion that's OK. I just use a larger input.
What I want to do is build a high thrust "lifter" device. The lifters built so far have lifted some few grams. I want to lift kilos.
Here is a page discussing the lifter devices:

http://jnaudin.free.fr/lifters*/main.htm [Broken]

I can do the change from AC to DC with a rectifier (actually the lifters can even work with AC so I might not need that.) The main problem is raising the voltage from 120V AC to 30,000V AC with a transformer when the electrical power is in the 3000 watt range.
I know power companies do this in both directions all the time. What I want is a low cost transformer that can do this or be able to build one on my own.

Bob

Last edited by a moderator: May 2, 2017
8. May 24, 2005

### Bystander

"Low cost?" "3kW?" "30kV?" You can have two of the three --- although "low cost" at 30 kV ain't all that low.

9. May 24, 2005

### RGClark

This bbs is doing that weird thing of putting extraneous asterisks in URL's again. When you click on the link for the lifters experiments page, if it doesn't open because there is that asterisk inserted in the address bar, just backspace over the asterisk and reload the page.

What I wanted to do was encourage extending the work done by amateurs with lifters to the kilowatts of power range. However, I am informed that
using high voltages while at the same time having high wattage means
the amperage would also be high. This can potentially be lethal.
There are relatively inexpensive ways of transforming the low voltage
put out by electrical generators to the tens of thousands of volts you
need for the lifters. If you have experience working with high voltage
and amperage, then you already know what they are.
It should not be attempted unless you are already well experienced
with working on and in high power electrical supplies.

Bob Clark

10. May 29, 2005

### Omegatron

You have a bridge rectifier that can handle 30 kV at 3 kW??

Really? I don't think that would work.

Yeah, you should probably ask the power company. :-)

11. Jun 29, 2005

### Rogue Physicist

The first step in your research is to investigate high wattage / high voltage transformers. These present special problems, like insulating the coils!

Such transformers have been actually designed and used in military equipment for radio transmitters and RADAR. I noticed you said 120 VAC but you didn't specify the frequency of the power source. That is okay, but high frequencies present another technical hurdle. (none of these factors help cost, although you can make the transformer yourself.)

If you are thinking of doing this and want to overcome the problem of finding an 'off the shelf' xformer, you can always connect the secondaries of a large set of xformers in series: Here you have to be very careful (there are serious special precautions needed), since there are technical problems and dangers in handling the resultant high voltages, and also in preventing the failure of one component causing a catastrophe.

Look into older Ham radio transmitter designs for ideas on power output transformer requirements, especially commercial radio station equipment.

Like others before you, you will discover that you will have to resort to 'tubes' for the power rectifiers, not semi-conductors. Even here, the incredible voltages you want need special circuit designs. I recently doubled the high voltage in a tube circuit in order to achieve other design goals: even this little jump in voltage (450 v to 1000 v) required serious precautions and careful design to avoid dangerous conditions in case of small part failures like resistors and capacitors.

Normally, people don't even think about the 'voltage' rating of a resistor, but in this case its real and very important that you don't exceed sensible limits. Capacitors are particularly sensitive to surge-voltages and high-tension.

Last edited: Jun 29, 2005
12. Jul 2, 2005

### CharlesP

Ions?

This lifter thing just looks like the action of ions under high voltage. I have felt the "wind" caused by such a near discharge. It is very weak, uses small current, and is strictly conventional physics. In my case I used two needles or a needle and a wire ring. Anything over 20KV would be fine. Low current is preferred so you won't get shocked too bad if there is a mistake. It would be difficult to make a vehicle using this method for lift and I doubt if it would be able to leave the atmosphere.

13. Jul 10, 2005

### Random

There is a NASA page discussing their work with this sort of thing. They covered it fairly thoroughly back in the 60's and early 70's.
The lifter does indeed work by íon wind' they conclude. It will not work ín vacua' - every experiment to try this shows it doesnt. 30Kv is a very modest performance for even the smallest of Tesla coils, but that's high frequency AC. The DC requirement is met by joining the top of the TC to your apparatus (effectively another capacitor) with a wire of high resistance. The current flow from one plate of a capacitor to another when joined by a high resistance is unidirectional - DC in other words. Your challenge is to find a substance that does not behave like a conductor at TC frequencies... Perhaps you might find a simple Van Der Graaf generator easier. The smallest output would be about 100Kv from an elastic band and a couple of empty coffee tins (my 10 y.o. son built one -they're easy)
So, Voltage is not nearly the problem you think it may be.. getting that voltage at the power you ask, and having it be a DC current - cheaply? easily? Sorry. Only by lots of work or lots of dollars..

14. Jul 10, 2005

### Omegatron

Not to mention that it could be brought down super easily by just shorting out the conductors. It only creates ion wind when there's a corona; not an arc.

Why do you want that much current, anyway?

15. Jan 20, 2008

### clivehansen

Building a transformer