Anyone played with Planar Transformers?

[Danko]

Hi!


I have bought one of this cute transformer in a shop:
http://sziget.mine.nu/~danko/aramkor...l/dscn8130.jpg
http://sziget.mine.nu/~danko/aramkor...l/dscn8133.jpg

It's a planar transformer. Unfortunately, at the shop thew know nothing about this.
Does anyone know something of it? What is the primary:secondary turns ratio?
What is the optimal operating frequency?
Yes, i have goooooogled, but I have found nothing.
On the Payton Group website I couldn't find this trafo.

[Joseph Hynes]

Unfortunately, I don't think that planar X-formers and transformers in general are so systematically part-numbered and labelled that you can identify one from the markings.

Many surplus parts were custom made for industrial customers, ans specs are not public, and the part number is not an off-the-shelf part.

You'll just have to measure pri/sec inductance with an inductance meter. To determine ratios you'll need to feed a known amplitude sine wave from a waveform generator into one winding and measure the amplitude at all other windings. You know which terminals pair up as windings from DC resistance measurements.

What application are you trying to use this for?

Most planars tend to have relatively few turns (too few for a mains-fed SMPS)
mostly, they are used in telecom (48V) applications, where low-voltage/high currents are used.

[Danko]

DC resistance measuring is quite difficult, becouse there are 1 and 2 turns from very heavy copper. Only a few milliOhm.

I hope I can play with this cute X-former, in a push-pull car-SMPS, from 12V

Thanks, Joseph!!

[Joseph Hynes]

You don't worry about the milliohms.
You just use the ohmmeter to know which terminals lead to the same winding, so that THEN, you know between which terminals to measure inductance, voltage, etc.

I guess 12V car applicatins are a possibility...

[AndrewT]

Hi,
is it air cored? or is there some ferrite in there?

Certainly only suitable for higher frequency.

[Danko]

Yes' it's air cooled. But on the top of the core, tehere's a 2x3cm totally flat area. Ideal, to mount some heatsink on it. :-)

[Joseph Hynes]

It is ferrite cored, not air cored.

In the pictures, what do you think is that big dark rectangular thing in the middle?

[Danko]

Oh, you wrote CORED. I read COOLED.

Sorry :-)

The core area is 126mm^2 (6x21mm)