I wouldn't use bell transformers for this project, a local shop sells
good xformers designed for projects such as this at about 6$, just at
30VCT instead of 60. Kind of related, I've been using a bell
transformer for a power supply for quite some time now (simple LM317
circuit), provides a good 1.5A at around 22V continuiously. I'm sure
if I upped the current w/ a more hefty regulator circuit it would fail
quickly, but it's worked for a few years now w/ no sign of giving up
(I don't really care if it does, no big loss, but it's a nice under
table supply w/ the switched potentiometer sticking out, provides for
a quick 1.2-22VDC. Again, thanks for the posts, especially for
driving me away from the torroidal idea, i'm sure it would have ended
up in a headache and much wasted wire. Thanks, Steve
On Sun, 20 Jul 2003 23:41:03 GMT, lcoe
wrote:

its wrote:
As I expected, way more effort than I wanted to put into it. I can
get good quality 30VCT transformers very easily. According to James
Sweet it would be fine to stack these. Sounds like the solution I
need, these xformers are the right size and current I need, and
cheap...probably just do this. Thanks for all the good posts, Steve
On Sun, 20 Jul 2003 16:57:42 GMT, "Peter Gottlieb"
wrote:

the actual output of a bell xfmr is higher w/no or light load, and as
others point out, drops significantly w/increased/short loading. but
with only a 1a requirement, you may still consider this option.
they also make (commonly avail) 24vac models designed for a/c, where
control wiring is longer. these put out about 36vac unloaded.

good luck, --Loren

There are a lot of design issues involved in winding a transformer - too
many to get into here in detail. Your basic issues a

1) Core material and saturation level
2) Enough primary windings to get sufficient field but not saturate core.
3) Thickness of primary winding.
4) Isolation between primary and secondary.
5) Secondary winding - turns and thickness.
6) Losses and temperature rise.
7) Change of characteristics as temperature rises.
8) Making it fit on a particular core/bobbin.

Best would be to find a transformer of similar power level where the primary
is wound first and you can remove the secondary and replace with your own.

I have a big Excel spreadsheet somewhere which assists in transformer design
but I'm not sure I can still find it and it does require some knowledge and
experience to use.


its you wrote in message
...
Kind of an off question, but I'm searching for a 60V CT (30-0-30)
transformer (1-2A is fine) for an amplifier I've been building. Would
I be better off just shelling out the cash and getting one, or is it
realtively easy to build your own (there are all sorts of torridial
cores avaliable at a local store, all for under 5$) I realize that
purchasing one would of course be the ideal situation, but I don't
particularily feel like spending 35$ for just a transformer... Anyone
have any recommendations where to look to buy one of these? Is
homebrewing one of these transformers relatively complicated? All
thoughs, including negative, are appreciated. Thanks in advance,
Steve