I was hoping with this controller to track down the explosions, but from the tests i need 80+ volts on my coil to get re triggering and my fet died straight away, shall i try limiting the current or do you not feel it was excess current that caused the failure.
If it was a large dv/dt that killed the fet maybe i should try a fet with a higher volts rating.
You have added more questions. You call it re-triggering. Maybe it isn't. Re-triggering at the FET may just be a result not a cause. Is it really related to voltage, current or both? If voltage then add a small capacitance across the FET. If current then place a small inductance between the coil and the FET. Either will change the frequency but will they make the FET live through a higher coil drive voltage? I suspect it is a voltage issue destroying the gate junction. Here is where I would try Lindsay's suggestion. Maybe to prove my theory with the white noise, i should build an amp and white noise generator and inject this into 1 coil of a bifilar and then inject sharp pulses in the other bifilat coil.
I have doubts creating spatial effects in a single coil will result in much, but who knows? Do we know why the pulse appears with 1 pulse above 270khz but requires 1 pulse and then a delayed pulse below 270khz to get a sharp pulse.
I think the second pulse simulates a higher frequency on a longer wire. I use an external pulse to pinch current on another wire so it will 'fit better'<?>... long story. I think I told that one to you and .99 already. Reestablish the test with these results and trim the wire. If the cutoff moves higher then you'll know the point is related to travel time through the wire. It won't be related to wavelength, perhaps pulse rise time instead? Is 270 the change point for other coil lengths? Is there anything else that can vary that 270 number? Ambient temperature? Something crazy like time-of-day? Do i start trying to measure the power in the pulse verses power used to generate
Your results are differing from mine so I'm not sure you are at a point where it will be easy enough to measure accurately. You do have a lot of 'hash' going on. Maybe you can wrap your noisy coil in a secondary coil for measurements?
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Topic: Controller No 4 - Dual Fet Driver - Looking for Explosions in Wires (Read 61618 times)
