Hi! Anyone winding OT's and PT's here?

[nicksorenson]

There's a great tutorial on making OT's in the old ITT book Reference Data for Radio Engineers, available for download: http://www.pmillett.com/technical_books_online.htm Chapter 11 is basically a step-by-step method for designing and building an OT, PT or inductor.

One very important part of an OT is the type of laminations you use. Apparently it is very hard to get the good lamination material these days. The different materials will react differently when it is saturated, some of the easily obtained material will make the transformer sound harsher than the good audio stuff. I'm not sure where you can get the good audio laminations, short of finding an old blown transformer and saving the laminations out of it. And if the transformer is potted with tar or varnish, it may be VERY hard to disassemble.

But if you can get the laminations and other materials, and can deal with the winding, designing and building OT's doesn't look too terribly hard. It actually looks like a lot of fun, many possibilities exist there for tweaking tone. Winding custom transformers and speaker reconing are perhaps the two main fields us hobbyists find hard to work with and learn about; both are hard disciplines to get involved with but are critical for tone.

You can get laminations from www.tempel.com.

[Steve Conner]

Transformer cores shouldn't saturate as the frequency is increased. Saturation is something that happens on loud bass notes only.

When you say the "inductance goes to zero" you are more likely to be seeing some effect related to self-capacitance.

[Joe Gwinn]

Transformer cores shouldn't saturate as the frequency is increased. Saturation is something that happens on loud bass notes only.

When you say the "inductance goes to zero" you are more likely to be seeing some effect related to self-capacitance.

Right. It sounds like what is being seen is self-resonance, where the self-capacitance cancels the self-inductance. Below this frequency, an inductor looks like an inductor. Above, an inductor looks like a capacitor.

[Joe Gwinn]

There are also a number of Taiwanese and Chinese winders around now that are basically rip-offs of the Japanese equipment, which were largely rip-offs of european equipment like Meteor. For about $3K you can get 95% of the precision and functionality of the Tanacs. If I was starting over...that's what I'd be using.

Hmm. Could you name and rate the main brands? I'd been looking at the AX-3, but never could talk myself into one, and alternatives are nice.

[matndona]

Basic Winding machines

typical Asia machines:
http://www.coilwinding.com.tw/

A US site that looks like they're selling something like this:
http://www.mcsinc.net/NewMachineLine.html
The 100X looks like a good example

I've used machines from Elmer and Leader. $2500 - $3500 would get you a single spindle CNC with traverse but you'd need to arrange the shipment. US Distribs generally mark this up 60-80%.