Re: [CAD_CAM_EDM_DRO] Toroid transformers

At 04:45 AM 12/19/00 -0700, you wrote:

>I was wondering if anyone has experience with using Toroid transformers for
>their power supply?

Yes, there is nothing wrong with them. Be careful not to damage the wires
where they come out of the winding by squeezing them (don't mount it upside
down). The cost is a bit higher than E-I transformers, but they are slightly
better in some regards. There is a local manufacturer here in Toronto, so
I can get them at retail for fairly reasonable onesy-twosey prices, in the
200VA-500VA range (IIRC). They are nice and flat so they fit into rack mount
equipment very well, and regulation is a bit better. They don't buzz IME
(vaccum impregnated). There is a manufacturer that will supply pre-wound
toroids with up to 1000VA primaries/cores, and you wind the secondary. I found
this useful when I needed 1000A at very low voltage.

The only gotcha I can think of is that they draw a larger surge current on
turn-on than regular transformers, you definitely need a slow-blow fuse.

BTW, they are really not much different to wind than regular transformers
if you have the right machine. It has a large wheel like a bicycle rim that
has a gap that moves so it can be slipped over the core. The big spool is
then wound with the entire length of wire to be used for the winding, and
then the spool rotates and the toroidal core slowly rotates around its
center axis as the wire is paid out onto it (over the edge). It requires
one machine per core at at time, whereas conventional transformer bobbins
are often wound four-up on a somewhat less expensive machine.

Best regards,




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