power transformers (was imsai 2)

From: Dave Dameron <ddameron_at_earthlink.net>
Date: Wed Aug 18 22:31:07 1999

Hi Tony and all,
At 03:28 AM 8/19/99 +0100, you wrote:
>> Yes. Good numbers to start with for power transformers are (US
>> measurements, I am sure there are equivalent ones in use elsewhere):
>> 6 turns/volt/square inch of core.
>
>We use 8 turns/volt on a 1 sq inch core over here, presumably because we
>use 50Hz mains and so need larger transformers.
Yes the number I gave was for 60Hz here. The 50Hz would of course give your
number, both being approximate.
>
>FWIW those transformer kits I mentioned give the turns/volt that the
>primaries are would with, and thus what you use for the secondaries.

I looked here for an equivalent source without luck, which isn't too bad
for 1X units where I just strip and rewind the secondary of an existing
transformer.
Rewinding the primary isn't too bad (120 Volts) if also required.
>
>> For AWG 23 wire, 1 Amp and area changes by 2x for every 3 gauge numbers.
>
>There are, alas, many different wire gauges in use. I normally refer to
>the tables in the 'Rubber Bible'[1] before doing any serious designing.
>
Yes, It can be confusing, there are at least 6 wire gauges I see in the CRC
Handbook. I know of AWG and SWG (for UK?). If in doubt I give the diameter
of the wire (AWG 23 = 0.57mm diameter). I usually use wire tables from
other places that the 'Rubber Bible' that include different enamel wire
sizes and types, not "bare" copper.
-Dave
Received on Wed Aug 18 1999 - 22:31:07 BST