Audio Driver

[Farlander]

Hey people
I've spent the last months building and rebuilding 555 timers, burning up FETS, frying chips, and needless to say I'm a little tired.  So, I have a new idea.

I have several 1" EMF filters for power cords, they are non-magnetic ferrite, C-clamp style, shaped like a trough, square on the outside but with a hole in the center for the wire to pass through.  I opened one, wound 10 turns primary and 20 turns secondary (on opposing halves, so as to have an air gap) and hooked it to my 12V pulsed DC generator.  I got 170V spikes on the secondary output, at 2x the input frequency!  I was pretty surprised that with a 2x transformer I was getting +10x voltage.

But alas, the mosfet fried again, so now I want to use my 100W stereo receiver to drive the coil.  I have a tone generator on my laptop to set proper frequency/gating.  The question is, what precautions should I take to avoid burning out my stereo/laptop?  What transformer specs would be most appropriate?  Thanks