Polarity of an xray transformer?

[Andrew Huot]

Im looking at an xray transformer on Ebay:

http://www.ebay.com/itm/300818129906?ss ... 1423.l2649

But can't figure out the polarity. There's a diagram in the pictures which doesnt seem to answer the question and the seller has no idea. Any advice?

Thank you so much!

[Tyler Christensen]

Based on the schematic, it is an AC output so you add external rectification and can pick the polarity by how you set that up.

[Chris Bradley]

I do wish people would have common sense enough to realise that posting anything from ebay is transient, and in a few weeks time the ebay item will disappear and any readers of this thread will be left scratching their heads.

Please use a bit of sense and put ebay stuff in 'trading post' where it will get deleted.

If (big If) it is a particular thing of sufficient merit for a discussion, make a copy of it like I've done, below. *Then* the thread will make sense in the furture.

Anyhow, this looks too small to match the 65kV x 7mA ratings it's been given. The power of a transformer is related to its core type, core size and operating frequency. For a 60Hz steel cored transformer (I say 60Hz because the 'information sheet' [looks like an 8 yr old has drawn it on powerpoint] says to use a variac) I'd have expected something substantially bigger.

Whether this is a ferrite transformer is anyone's guess, but if so it doesn't look like it has been treated nice as they are a fair more delicate than steel transformers.

As for positive or negative: The silver terminal is the positive half the time, and negative for the rest. The other silver terminal is the negative terminal half the time, and positive for the rest. (... If you think I'm trying to be 'funny', then all I am doing is using humour with you to prepare you for the steep learning curve you are about it stumble up!)

[Rich Feldman]

Actually that looks about the right size for a 65 kVp (45 kV RMS), 7 mA dental x-ray transformer.
Remember, the typical duty cycle is < 1 second on, > 1 minute off. These transformers are designed to operate even closer to saturation than those in MOT's.

As Chris warned, the ebay offer is already over. Closed with no sale.