Anyone built the JLN 30kV DC supply? / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

Anyone built the JLN 30kV DC supply?

1 2 next

Move Thread

LAN_403

Steve Hobley

Wed Oct 27 2010, 05:07PM

Registered Member #1731 Joined: Thu Oct 02 2008, 02:22PM
Location: Indiana
Posts: 52

I want to give a demonstration of the "lifter" effect, and so I need to put together a supply.

The JLN site seems to have the "standard" design using a driver->flyback->voltage tripler.

Does anyone have any experience of building one?

I can see many flyback transformers available online for around $20 (I just threw out an old TV set last month too - could have kicked myself) but is there anything I need to be aware of when selecting one?

The voltage tripler seems to be the NTE521 (about $30) - can someone confirm that this will perform correctly?

Thanks,
Steve

Antonio

Wed Oct 27 2010, 10:27PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

A regular CRT TV/monitor fyback transformer without a tripler is enough. I have something here:

Avi

Sat Oct 30 2010, 03:02AM

Registered Member #580 Joined: Mon Mar 12 2007, 03:17PM
Location: Melbourne, Australia
Posts: 410

I made one, its only for use with AC flybacks, any other type is already 30kv and has internals diodes or an internal voltage tripler in the flyback package

Steve Hobley

Mon Nov 08 2010, 03:05PM

Registered Member #1731 Joined: Thu Oct 02 2008, 02:22PM
Location: Indiana
Posts: 52

So I stripped an old RCA TV for parts the other day, and managed to extract a flyback labelled PN: 2F25010-503 which after some Googling is equivalent to the HR7280.

I found this schematic for the HR7280:

On Naudin's page he uses the HR7839:

Page:

PSU Schematic :

HR7839 Schematic :

where he connects 1+2 to the supply, 8 to GND and HV is out - it looks like his ratio of turns is going to be higher, because in mine (HR7280) I am supposed to connect between 6 and 9, and that looks like more turns on the primary.

Would connecting between 5+9 in mine, be the same as connecting between 1+2 on his.

I'm not sure how I would go about testing the flyback connections without the correct test equipment - I've done some simple resistance measurements on the coils and got results that I would expect. But I can't test the HV line because of the diodes.

Any thoughts?

Proud Mary

Mon Nov 08 2010, 04:15PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Steve Hobley wrote ...

Would connecting between 5+9 in mine, be the same as connecting between 1+2 on his.

The primary winding on HR7280 is across pins 6 & 9. The taps are auto-transformer take-outs. LOPT designers compete with eachother to see who can power the most discrete sub-circuits in a TV from the one transformer, which should explain the proliferation of taps and windings on most modern diode-split LOPTs.

You will note from the HR Diemen datasheet that HR7280 is intended to supply 20.7kV, while the HR7839 used by the mad Frenchman in his many strange and unbelievable marvels is an altogether more muscular component with an intended output of 29.5kV.

I say "intended output" to emphasise the figures are given for normal television service, where the LOPT must run 24/7/365.

Steve Hobley

Mon Nov 08 2010, 04:42PM

Registered Member #1731 Joined: Thu Oct 02 2008, 02:22PM
Location: Indiana
Posts: 52

Thanks for the reply.

So I need to look at a bigger television then...?

I'm also struggling to find a transformer that can supply the 48v AC - can I put two 24v in parallel to accomplish this?
I guess the ferrite cores are not "linked" so you cannot double the voltage output, only the current handling.

Steve Hobley

Thu Nov 11 2010, 04:06AM

Registered Member #1731 Joined: Thu Oct 02 2008, 02:22PM
Location: Indiana
Posts: 52

So...

I built the basic Naudin driver using parts from the TV set I salvaged, at the moment I'm driving the primary with a 12v lead acid battery. I set the frequency to 15kHz.

When I switch on the S2000N transistor gets warm and I can hear the TV "singing" noise after a couple of seconds (the sound goes away when I replace the primary connection with a simple resistor) - so I think it's working, but I can't seem to draw an arc from the HV terminal.

The design calls for 50V as a drive - I can hook up a variable transformer / rectifier and cap to provide anything from 0 to 100V DC.

So I'm thinking of doing that next - can anyone tell me if there's anything wrong with this approach?

Bjørn

Thu Nov 11 2010, 05:44AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

You can put transformers in series, just make sure you got the phase correctly or the voltages will be subtracted instead of added.

Do you have an oscilloscope? If not you really should invest in one, it will make everything a lot simpler.

If you got a 7812 regulator you need more than 12V for reliable operation since the regulators usually like to drop 2-3V.

Steve Hobley

Thu Nov 11 2010, 01:22PM

Registered Member #1731 Joined: Thu Oct 02 2008, 02:22PM
Location: Indiana
Posts: 52

Thanks for the response.

Yes I do have a couple of scopes.

The 12V regulator is just to supply the electronics, the batteries are pushing the primary coil.
I think I'm going to go ahead and try around 50V DC and see what happens. The fact that I'm getting the singing noise is encouraging.

I brought up the question of "ganging" transformers on Dutchforce and they confirmed that you can build approx 50v from 2 24v transformers. I have several variacs however, so I don't think I need to go down that path.

Patrick

Thu Nov 11 2010, 08:50PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

becareful using an o-scope even on the low voltage side, there can be kick-back to beyond 300 volts, iggies, and flybacks can murder instruments quite easily.

1 2 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob