Transformers - where to start!!

[AlanBeckett]

In days of of there were a Plethora of Wire Gauges. The best known is 'Standard Wire Gauge' - http://en.wikipedia.org/wiki/Standard_wire_gauge
It's all Metric now

Alan

[Mark R]

The thread Ed refers to in post #7 is here

http://golbornevintageradio.co.uk/forum/...p?tid=2028

[Bushbaby]

Thank you kind Sir.

Regards

Rob

[Alan Douglas]

I don't see it mentioned in the referenced articles/posts, but if your supply spool is large enough and has smooth edges, it can sit on the floor between your feet, on end, and you take the wire off over the top flange.  A loose-fitting sleeve (I use packing foam) around the spool keeps the wire from tangling.  When I wound transformers at work, with 10-lb supply spools, I did this with even rather heavy gauge wire (#20 AWG) and there was no problem doing it this way.  It puts a twist in the wire but that makes no difference.   The big advantage is not having to worry about the inertia of a rotating supply spool, and not having to keep one hand free to control it.

This is the winder I built about 40 years ago:
   
It uses a 28VDC motor with a foot-operated speed control.  The turns counter has a worm engaging a 100-tooth gear and registers thousands of turns. There's a slip clutch for resetting the zero.

[AlanBeckett]

Many moons ago, in a land far far away, I needed some wire for the Job I was doing. My Colleague advised that the Factory Stores would have something suitable. Sure enough they did, but it came in a 40 Gallon Drum!
Getting it back to the Lab was, to say the least, a challenge

Alan

[Alan Douglas]

At the motor shop it came coiled in 5-gallon pails and you pulled it out as required. That worked fine as long as everyone was careful not to lose the end.

[Radio Fixer]

Nice winder you made there Alan. Must be great to have machining skills ... guess you had access to a lathe and a mill.

I have used the fishing reel method of letting the wire spool off the flange and as you say its very effective. I used to rewind field coils with a battery drill in the vice. Got my big foot caught in the wire once ...

Gary

[Alan Douglas]

I had a Unimat at the time, but had access to the machine shop at work, and their offcuts pile. I did get one of the real machinists to cut that worm (1/4-20 thread, which happened to match the gear). You had to know when to back off the cutting tool since there is no relief area at either end.

[Ed_Dinning]

Hi Mark, thanks for finding the notes, it saves me a lot of re-typing.
If anyone has queries please mail me and I will do my best to answer.

Typical wire current densities are 2000A per in sq or 3A perm sq. Plenty of wire tables about that you can work backwards to get the current for a particular metric or imperial size; it should be easy to do on an EXEL sheet.

Note that wires are rated as to their bare diameter. Coated diameters are larger due to 1 or 2 layers of coating (sometimes 3). Use bare dia for current and coated dia for bobbin fill.

Questions will also be answered on Sun at Golbourne.

Ed