Claimed OU circuit of Rosemary Ainslie

[poynt99]

Rose,

I would query TK on those questions.

Go to your "PROFILE", then "Modify Profile" tab, then choose "Account Settings" and make sure that by "Preferred language" "English" is set. If it is already English, then I'm not sure what the problem or solution might be other than to PM Stefan.

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[poynt99]

Rose,

Any idea what's up with Harvey?

I am trying my best to understand his request. Rather than attempt to provide the information I need and asked for in order to obtain the simulation results he wants to see, he shuns my efforts so far and says he'll do it himself.

Good luck to him with that if he's so inclined.

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[Rosemary Ainslie]

I'm intrigued with something.  Why does the voltage at the gate of the MOSFET swing high and above zero when the inductor is dumping a below zero spike?  And MH then uses this evidence that the gate is getting a 'punch' from the voltage in the inductor.  What does the voltage at the 'drain' indicate when the MOSFET is off?

I was trying to ask MH this.  Can you explain?

Regarding Harvey - I don't know enough about the problem to comment but clearly you're missing each other.  My take was that you were meant to stress the paramaters of Spice to see if it would register anomalies precisely by adding to the inductance on the resistor.  But I really don't know.  I think his expertise is in a different league to yours so it's way beyond my own.

I'd love to see that demo MH proposed.

[Rosemary Ainslie]

that's another thing I can't do is amend my posts.  Have no idea which 'german' word applies. 

Have just re-read the post.  By different 'league' I don't mean to diminish your own knowledge.  On the contrary.  It's just that his is even greater - but that's just my impression.

I'll try and contact Stephan when he gets on line.  I can alter everything in my profile bar 'start date' preferred language and something else that I forget.

EDIT  Have found the edit instruction.  Poynt - I'm still not doing you justice regarding your knowledge.  Trust me, I'm blown away.  It's just with H I feel I'm in the grip of a tornedo.

[poynt99]

I'm intrigued with something.  Why does the voltage at the gate of the MOSFET swing high and above zero when the inductor is dumping a below zero spike?  And MH then uses this evidence that the gate is getting a 'punch' from the voltage in the inductor.  What does the voltage at the 'drain' indicate when the MOSFET is off?

Rose, the first high voltage spike (after the MOSFET turns OFF) on the Drain is actually in the positive direction (relative to Ground), and it is this spike that poses the "stress" on the unprotected MOSFET. This is the danger MH has warned of and it is there, especially when fast switching speeds are attained.

If the MOSFET Gate is driven through a series resistance (such as how everyone on this experiment seems to be doing), then there will be feed-through of this spike from the Drain to Gate via the G-D capacitance. In all my tests I'm using a 100 Ohm resistance in the Gate and I see the biggest spike at the Gate pin is in the negative direction and it is about -2V.

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