Hi Rick
Just as a comment - I have built the old type of square wave inverter
(approx 50 - 60 cycles) which use just a few components and an iron
transformer. Now in one sense this is the basis of what you want -
except that intead of using an iron core you use a ferrite core at say
10 kilocycles.
Most of the cheap modified square wave inverters first generate the
120 volts (actually more like the peak of a sine wave at 170volts) at
say 10kc/s, which is then rectified to DC.
This is then chopped by a bridge circuit to AC, using a circuit that
turns on the output for less than a full half-cycle.
The problem of reverse engineering is that the ferrite transformers in
the first stage are wound for approx 150 volt out - and as a sealed
transformer it would be hard to alter them.
(Note - I am approximating voltages - we use 230 volts here in NZ)
You don't say how much power you want to handle, but if you could find
a suitable core (eg an old line output ferrite core from a TV set),
you might be able to wind a suitable transformer. This would then be
driven at say 10kc/s, using some high power fet's - potentially these
might be from a cheap inverter (there are many circuits to do this on
the internet).
Then you would rectify and smooth the output for your 50+ volts DC.
The actual frequency of operation would be relatively unimportant,
provided it was fast enough for the core.
There IS a way to do what you want using a high-power light dimmer
(yes, even with a square wave) - just straight out of the 120 volt
inverter and then rectified - but you might have to be careful if you
are charging a 50 volt battery (which I suspect is what you want to
do) as the peaks of the current may be too large for the dimmer (been
there - done that - one burnt out 1kw dimmer later!).
Give a few more details of what you want to DO, and how you are
sourcing the 12v (from a battery - of perhaps to step up the output of
a solar panel?) - then I might have more suggestions.
Eric Sears ZL2BMI
