I'll agree with G. IMO, current and magnetic field change isn't the culprit. You can certainly create a reasonable EMP with a few micro-amps if the voltage is high enough and pulse width in the tens of ns.
If the culprit is an E1 then X
L won't matter. An E1 is almost all charge. In that time-frame there is no X
L, yet.
Is the targeted result avalanche of the FET or the anomalous patterns emanating from the coil?
Is the FET using silicon based junctions? Silicon junctions can change from a charge carrier to a charge hold and release. Avalanche and Snapback are two different things.
I think what is going on must be determined before working on a solution. If the damaging energy is an E1, primary result pulse of an EMP, then there isn't much to do except socket the devices. There are other things to try but not knowing them is probably why we aren't all carrying holstered EMP weapons
You may want to determine if the invisible reverse pulse is a result of a silicon junction. Tie the gate to S or D (depending upon the device type) and feed it like a detector diode. If you get powerful but incredibly short reverse conduction then the activity seen is probably more to do with release of stored charge than avalanche.(not talking about capacitive discharge - this silicon problem can create double digit ps spikes)
If the problem is EMP related then reducing voltage will make it harder to create the noisy coil. Decreasing pulse rate or increasing pulse width is also counterproductive. Not needing a delayed secondary pulse at higher frequencies is probably because the pulses are so close together each following pulse
is delayed in reference to the leading pulse.
The primary of a true EMP is a sudden burst of charge not a sudden change in a magnetic field. The magnetic change part is secondary and tertiary.
A diode in series? Maybe, if the anode is tied to the FET source and cathode to V-. you may want to try something besides silicon
If an E1 is the problem then that diode will produce an even charge across the FET and the new diode should fail instead of the FET.
Yes, the freewheel diode shunted in the FET is a waste of time for incredibly short pulses. Why? Diodes aren't on by default (forward current). They turn on when a current is applied. If you want a diode to always be on then maybe a zero-bias type is a better idea. Anything less may not conduct until after the spike is done. Another reason why the FET and diode with running current flow are the only ones to fry? They are already on. The collision happens inside them instead of the coil when timing is just right/wrong
Ok. The beers are starting to take hold. I'll stop pummeling y'all with my hot wind.
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Topic: Controller No 4 - Dual Fet Driver - Looking for Explosions in Wires (Read 59552 times)
