Off-the-Shelf 70KHz Step-Up Transformer

I don't think you'll find one that's "efficient".

Best luck will be stepping it up from 12V to 120 or so, then driving a common CRT FBT, which will do 20-30kV depending on size (up to 60kV for the most powerful projection sets, I believe?).

If you're lucky, you can use a portable TV FBT ... but I doubt these were large enough to need 10-20kV. You could use a CW multiplier, but this is only possible if the output is AC, which it usually isn't. You may get lucky and find one that's used with a tripler already, so the transformer itself is AC and can be multiplied up as needed.

FBTs are also optimized for a harmonic of 15kHz. 70 exactly might not work quite well enough. (Why so particular, anyway?)

You might also have some luck with unconventional approaches, like a very small Van de Graff, which need not require any transformer (or 70kHz) at all.

Tim

If you can find an old - discarded - lap-top with cold-cathode back-lighting, you've can probably find most of what you want.

Check out Linear Technology's application notes AN45, AN49, AN51, AN55, AN61, AN65 on the technology used.

If you can find an old - discarded - lap-top with cold-cathode back-lighting, you've can probably find most of what you want.

Check out Linear Technology's application notes AN45, AN49, AN51, AN55, AN61, AN65 on the technology used.

Maybe an audio plate-to-speaker transformer could produce in the region of 500V or so. Problem is they will not have the insulation to withstand 2KV or more

- meaning not practical to drive a bunch in parallel then connect outputs in series. Would need isolation transformers...

TV frequency is too low, (around 16KHZ)

so this is a one-off

Maybe the flyback transformer from a CRT computer monitor, the last CRT models had line rates in that ballpark. you'll perhaps need to replace the primary with 10 to 20 turns.

It might be easier to rectify the 12V and use that to run a tazer energiser putchased from ebay.

you can buy a laptop inverter (eg: for lenovo T400) for a few dollars on . 2-4 week free delivery. only about 3KV out though.

That could be worth a try. I can get up to 120V using an audio coupling transformer.

Not sure how many turns primary it will drive on the FBT though. May need a series resistor.

That is the resonance of the loaddue to a contained pieoi element.

kevin Foster

Huh...

Could you tell us more about your system?

Tim

A number would be useful, here. CCFL lighting (used to be the backlight on LCD screens, but is getting replaced with LEDs) requires something like this; you can get 1:100 transformers for that frequency, with over 1 kV outputs. For the 10kV range, you'll need to wind your own boost transformer and pot it (or there will be corona problems), but off-the-shelf parts will give you a good start

Kevin Foster schreef op 08/05/2015 om 05:57 AM:

Perhaps several CCFL backlight inverter transformers in series could do the trick.

You might not have to kick up the voltage, there are almost always lower vo ltage secondaries fro scan derived supplies.

You will need to tune it to 70 KHz with its original damper capacitor. (if for an SDTV, for HHDTV or monitors it is a little diffrent) What's more, th ere might be a problem if you don't want DC because most of them had the HV rectifier built in.

You might have some luck contacting Asti Magnetics, though I haven't had an y contact with them since they were bought by Russell Industries. They have a website. If you can get ahold of Henry who used to run Asti he might be able to fix you up. No guarantees though but really, if they have something on the shelf that they can't even sell now for $20, you might score.

Thanks to everyone for their helpful suggestions.

I now have a few new ideas to try.

Kevin Foster