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BrianG · 05.02.2007, 05:37 PM

Most FETs, especially ones for PWM motor applications use a reverse biased zener/trancil/avalanche diode to shunt that reverse polarity spike over a certain value to protect the FETs.

Off topic, but somewhat related, story:
I once had an unknown inductance coil that when used with a simple oscillator circuit powered from a 4 AA batteries produced over 1,000v from the collapsing magnetic field! Felt like a cattle fence! :036: I had it set up so it charged through a resistor over several seconds and then dump the voltage all at once to a set of pads outside a project enclosure. The best part is I put a sign on the box that said "Don't touch" and left it unattended on a table. You can imagine how many yelps I heard. :017:

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BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	05.02.2007, 05:37 PM Most FETs, especially ones for PWM motor applications use a reverse biased zener/trancil/avalanche diode to shunt that reverse polarity spike over a certain value to protect the FETs. Off topic, but somewhat related, story: I once had an unknown inductance coil that when used with a simple oscillator circuit powered from a 4 AA batteries produced over 1,000v from the collapsing magnetic field! Felt like a cattle fence! :036: I had it set up so it charged through a resistor over several seconds and then dump the voltage all at once to a set of pads outside a project enclosure. The best part is I put a sign on the box that said "Don't touch" and left it unattended on a table. You can imagine how many yelps I heard. :017: