Transformer Input Meanings

This forum is for specialized infomation important to the construction and safe operation of the high voltage electrical supplies and related circuitry needed for fusor operation.
Post Reply
John Schrader
Posts: 4
Joined: Mon Jun 22, 2020 7:16 am
Real name: John Schrader

Transformer Input Meanings

Post by John Schrader » Mon Jun 22, 2020 7:23 am

I'm considering purchasing an xray transformer in eBay now that there seems to be some decent deals floating out and about.

Here's two I'm considering:
https://www.ebay.com/c/27013998742
https://www.ebay.com/itm/bennett-x-ray- ... SwpfpePByz

For the first, I assume P1 is the input power to the primary coil and P3 to the secondary coil. Can I just drive P3 & GND with my 220v variac. What does SHLD mean?

For the second I assume that mA on the top means mA test point with P1 and P2 being similar to the first one. What does high and low mean?

As an add-on these seem older much bulkier transformers - could they handle sufficiently being driven at 50 Hz from the variac or will they need higher frequency. I'm trying to avoid unpotting the transformer and simply using the mA test point w/ a fluke and my variac to confirm functionality.

Lastly what's the cable connection type for the anode and where can I find a suitable one online does anyone know?

Jerry Biehler
Posts: 900
Joined: Tue Nov 24, 2009 8:08 am
Real name:
Location: Beaverton, OR

Re: Transformer Input Meanings

Post by Jerry Biehler » Mon Jun 22, 2020 9:52 am

P1 , P2, or P3 are your primary connections. SHLD is shield, the shield on the cable supplying the power to the primary. If there is a shield it might be a high frequency drive transformer which you will need to either get or build a drive for it. With the physical size of both being so small I would be very surprised if they were not HF transformers.

User avatar
Rich Feldman
Posts: 1303
Joined: Mon Dec 21, 2009 11:59 pm
Real name: Rich Feldman
Location: Santa Clara County, CA, USA

Re: Transformer Input Meanings

Post by Rich Feldman » Mon Jun 22, 2020 2:34 pm

Agree with Jerry that the smallness implies high frequency. Compare size not with bare dental transformers (7 to 15 mA in 1-second bursts), but with potted 100 to 200 mA transformers for whole-spine radiography.

I can attest that the Bennett cathode and anode tanks need HF drive, in fact are designed for 100 kHz (!).
See my thread here viewtopic.php?f=18&t=9781
and that of Muhammad Faidzul, who made a driver for an identical-looking tank.
viewtopic.php?f=18&t=11088
bennett.jpg
bennett.jpg (51.86 KiB) Viewed 383 times
The tank in your second ebay listing is one for anode side, so HV polarity is positive. You would have to open it up and reverse a bunch of diodes -- see picture in my thread.

Ask the ebay vendors if the tanks come with HV cables; they might have those in another auction. Nothing you can't scratch build, for fusor work.

Just noticed a pair of Bennett inverter modules on ebay, and might make an offer.
https://www.ebay.com/itm/Bennett-PC-Boa ... Sw5cNYilF2
All models are wrong; some models are useful. -- George Box

John Futter
Posts: 1603
Joined: Thu Apr 22, 2004 2:29 am
Real name: John Futter
Contact:

Re: Transformer Input Meanings

Post by John Futter » Mon Jun 22, 2020 6:56 pm

John Should also do as the rules state
This is not the place for your first post

John Schrader
Posts: 4
Joined: Mon Jun 22, 2020 7:16 am
Real name: John Schrader

Re: Transformer Input Meanings

Post by John Schrader » Mon Jun 22, 2020 10:23 pm

This transformer seems like it'd be a much better fit if I don't want to have to worry about high frequency driving then?

https://www.ebay.com/itm/RIGAKU-9547-52 ... Sw9fZetK0J

User avatar
Rich Feldman
Posts: 1303
Joined: Mon Dec 21, 2009 11:59 pm
Real name: Rich Feldman
Location: Santa Clara County, CA, USA

Re: Transformer Input Meanings

Post by Rich Feldman » Mon Jun 22, 2020 10:50 pm

Still haven't seen anything about you in Please Introduce Yourself forum.

If you are grown up and experienced with ebay, then I guess you are prepared to pick up that big old Rigaku thing in Oxnard, California.
And know better than to offer more than half of the buy-it-now price ( seller has the option of counter-offering ).

My Bennett cathode and anode tank set came from ebay for less than $100. Less than $150 with tax and shipping.
Pretty expensive paperweights and door stops while in my custody, after a flurry of measuring and learning more than 5 years ago.
All models are wrong; some models are useful. -- George Box

John Schrader
Posts: 4
Joined: Mon Jun 22, 2020 7:16 am
Real name: John Schrader

Re: Transformer Input Meanings

Post by John Schrader » Mon Jun 22, 2020 11:42 pm

Didn't get around to it yet but I just tossed a post up.

I offered $300 for it - it's 6 hours drive for it but if it comes through I can drive down for a weekend and pick it up. $300 to get something that could work / do some interesting experiments off the bat seems like a solid deal.

Post Reply