Circuit diagram for a power supply that outputs about 25kv

[wolram]

Does anyone have a circuit diagram for a power supply that outputs about 25kv at a few mA dc.
25kv is just a ball park figure it could be 22 or 30 kv, or even better adjustable from 22 to 30.
Input would be 230v ac
Thanks.

 

[Astronuc]

Basically you want an AC/DC converter from 230V(AC)/25kV(DC). Basically 110:1, or 80-130:1 if one is doing a range of voltages. I imagine one could use a tap on the low voltage side.

There are probably off the shelf power supplies that do that.

 

[Phrak]

You might make do with a TV flyback transformer using a small 230VAC variac to adjust the voltage.

Depending on what you are doing, you might simply use the entire television plugged into a larger variac, complete with remote on/off switch It won't work if the flyback supply tries to regultage the output voltage back to nominal, though.

 

[waht]

TV flyback would be a good choice for the project, however the flybacks are designed to work at high frequencies. A 60 Hz input from the outlet will be absorbed by its core.

Luckily, flybacks have multiple primary windings needed to setup a relaxation type of oscillator using a transistor or two. Supply power is DC, so you need an AC/DC stage first.

The simplest way to adjust the output voltage is to vary the frequency because there is a relationship between the frequency and magnetic core power absorption. You can't change the frequency of the relaxation type of oscillator as you would have alter the primary windings, the solution would be a variable square wave oscillator driving the primary windings. Frequency 10 KHz to 20 KHz could do, depending on the core.


http://www.geocities.com/CapeCanaveral/Lab/5322/fly-drv2.gif

 

[Phrak]

TV flyback would be a good choice for the project, however the flybacks are designed to work at high frequencies. A 60 Hz input from the outlet will be absorbed by its core.

I expected someone might call me on this, good work. I was referring to the entire inverter + output rectifier. That'll teach me to use shorthand.

As Astronuc was talking about, it would be a lot easier for a one-off, to buy one, than build one.

As for a roll your own, you're schematic doesn't identify the core, the supplier of the core or the wind ratio or wire gauges to use. Gotta have them. What's the part number of the output rectifier? (Does he want DC or AC?)

I didn't find any suppliers of 25KV flyback inverters that would sell in quantities of one. Given that, I would scavange the supply from a television. The remaining problem with this approach is guestimating the voltage developed as evidenced by the size of the television screen and profile. Wolram would need a TV guy for that.

 

[Phrak]

Wolram. Do you want AC or DC output?

 

[TurtleMeister]

Does anyone have a circuit diagram for a power supply that outputs about 25kv at a few mA dc.
25kv is just a ball park figure it could be 22 or 30 kv, or even better adjustable from 22 to 30.
Input would be 230v ac
Thanks.

Does it have to be 230v input? If not then my first choice would be the flyback also. It's much lighter and cheaper. And it will probably already have the HV rectifier with it.
http://members.misty.com/don/samflyhv.html

 

[vk6kro]

You can get high voltage transformers for Neon lighting.
like this:
http://www.geocities.com/CapeCanaveral/Lab/5322/luminous.htm

 

[wolram]

Wolram. Do you want AC or DC output?

DC output, i intend to build an (ionic lifter), if i can buy a ready made PSU it will be better as i can use it for other projects.
Thanks for all the help guys.

 

[Phrak]

DC output, i intend to build an (ionic lifter), if i can buy a ready made PSU it will be better as i can use it for other projects.
Thanks for all the help guys.

OK, you might try digikey. You might also consider a neon sign light transformer, where you have to supply the rectifiers.

 

[berkeman]

DC output, i intend to build an (ionic lifter), if i can buy a ready made PSU it will be better as i can use it for other projects.
Thanks for all the help guys.

Do you mean filter instead of lifter, woolie?

 

[negitron]

Do you mean filter instead of lifter, woolie?

No, I'm pretty sure he means one of these.

 

[waht]

I built one these before with balsa wood and aluminum foil. For it to lift off you need more than 30 KV, and make the structre extremely light. I used a flyback transformer for the power supply, but had to over drive it up to 50 KV to increase the current. It worked for a while until the secondary winding arked and burned.

 

[berkeman]

No, I'm pretty sure he means one of these.

Huh, never seen that before. Thanks negitron.

 

[berkeman]

I built one these before with balsa wood and aluminum foil. For it to lift off you need more than 30 KV, and make the structre extremely light. I used a flyback transformer for the power supply, but had to over drive it up to 50 KV to increase the current. It worked for a while until the secondary winding arked and burned.

So you're saying this is a pretty safe activity for this OP to be working on...

 

[vk6kro]

They had this on Mythbusters a few months ago. It worked well.

It was supposedly an antigravity machine but probably works by generating an air flow downwards.

A van De Graaf generator or a Wimshurst machine could probably generate high voltages at enough current to make it work.

 

[negitron]

They had this on Mythbusters a few months ago. It worked well.
It was supposedly an antigravity machine but probably works by generating an air flow downwards.

Yep. The electric field ionizes air and accelerates the electrons upwards and the ions downwards; the latter having much greater mass than the former, almost all the thrust is upwards. Neat toy, but likely not practical for large-scale applications in the forseeable future.

 

[Bob S]

This ignition coil circuit with an NE555 and a 2n2055 transistor is good for about 30 kV (more than a neon transformer), but lacks a rectifier diode:
http://www.geocities.com/CapeCanaveral/lab/5322/coildrv.htm