On Sep 16, 8:46*pm, brian whatcott wrote:
Andy GD1MIP wrote:
Hi *I am building a (240volt in) 13.8 volt (out) PSU ...

* the transformer must have a secondary of 16.5 volt.

I have a Talema branded toroid I want to use, its spec is as follows
(from maker)...
73 Andy

Now that the ideas are cooking.... consider this.
1100 watt defunct microwaves can be had for the asking.
* * They have a particular transformer core design that makes it easy to
saw off the 1 KV secondary, and with the generous core window, you could
wind 18 to 20 turns of wire good for 10 amps. The turns per volt is not
much over 1 tpv.... * And you have a decent rectifier diode for the
spares box too....

Admitted - a bandsaw in the workshop makes a 15 minute job out of this
transformer hack.(if you don't nick the primary)

Brian W
KA5WOG

Brian, I have done this with old uwave transformers, the ones I could
knock out the magnetic shunt with a hammer and punch, but on the newer
ovens the shunt is a weld. Will these still work?

Jimmie