SHO protection circuit?

[blooze_man]

I know there's been a million threads about the sho, but i haven't seen a schematic that has the diode circuit that protects the transistor from blowing up. If anyone knows what it is and is willing to share, that would be cool.

[cpm]

I know there's been a million threads about the sho, but i haven't seen a schematic that has the diode circuit that protects the transistor from blowing up

uh... search more

[~arph]

A 9v1 Zener from source (I always mix source and drain up. So to be clear. The pin where the pot is at) to gate

[earthtonesaudio]

[petemoore]

  Take a look at AMZ mosfet Boost.
  The gate is 20volt thick glass, 21 or so volts will break it.
  9.1v zener protects it and lets any signal <9.1v pass.
  That's one super hot input signal, 2 or 3 volts'd do me I think.
  Once the mosfet is in it's less likely to see anything but small voltage...of course the input cable tip could touch a carpet fiber or something else with a charge on it. It is common for carpet fibers to get __kv on them...morgan enough to exceed gate max V.

[blooze_man]

cool. thanks

[earthtonesaudio]

The zener alone does help, but is not ideal.  Adding the resistor (in red in the drawing above) makes it about a billion times better.