RE: Microwave Oven Inverter PS, revealed

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: <sparks@xxxxxxxxxxxxxx>


> The real question is how would the control react to a fiery Tesla
> coil load??  The current would jump wildly!!  The little chip
> "should" see that as an acing tube or something and shutdown.  But
> there is not a lot of feedback there so the circuit might be
> easy to trick >:))

Actually, the problem of poor voltage regulation that makes these
inverters not-so-suitable for transmitter use makes them just right for
TC use.  A microwave oven supply needs to be current limited and blow-up
proof in case the magnetron arcs during operation.

In the case of a conventional iron core transformer, the magnetic shunts
protect the transformer, rectifier diodes and the maggie. In the
inverter shown here, there is actually a not-so-visible magnetic shunt
in the transformer.

If you look closely, you will notice that the primary winding passes
over one of the outside legs of the ferrite core.  At first glance, this
is not unusual - after all, you'll see LOPT's wound the same way.  But -
take a closer look!  Where's the secondary winding?  Why, it's wound
over the hidden center leg of the ferrite core!  That means that half of
the primary flux has a shunt path through the outer core leg that is
surrounded by the primary winding. It will behave just like a
conventional iron core magnetically shunted transformer.

A heavy load in TC service will result in the supply regulating at a
constant power level and (hopefully!) protecting itself from
destruction.

73,

Ralph   W5JGV - WC2XSR/13 - WD2XSH/7

http://w5jgv.com
http://500kc.com
http://spectrotek.com
http://kc5cah.com