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No this one is just 15v, 0v to 15v. No splitting for negative voltage. But some people suggested that it might be that I needed a snubber. I added a 0.01uF cap and 4.7Ohm resistor, and now the spikes are much smaller. I believe there's a good chance that the previous failures were due to no snubber, and maybe bad soldering technique before. The ringing that was from drain to source during turn-on was making its way to gate to source, and high current probably caused voltages that kept trying to go well over the 30v limit. The TVS diode probably got overworked and blew. I think it will actually work this time!
Next, I'm going to use the same snubber, but at 24v, and see what affect increased voltage has the spikes. The snubber resistor will have to dissipate more power, and the mosfet's output capacitance (I think they call it coss) drops the higher the voltage... It will be interesting to see how it goes. Then I'll install some mica capacitors (470pF) and try it out at maybe 144v. You have to use much smaller capacitance at that voltage since the power requirement of the resistor goes through the roof.
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