I'm newbie in electronics looking for an advice on how to properly limit gate voltage for BUZ11 MOSFET in my PWM regulator for a DC motor. Currently I'm using it with 12V power supply and it works OK, but I want to use it with 25,2V (LiPo 6S), so the gate voltage should be limited to < 20V. Thinking about Zener diode 1N4745A (16V). Will it work for schematic below?

Schematic (for 12V power supply): enter image description here

Zener diode:

enter image description here

UPD I'll also use 78L12 LDO to power NE555.

  • \$\begingroup\$ It might, but that won't be the only problem - the NE555 can only hande 18V so it would also fry if connected to 25V. \$\endgroup\$
    – Justme
    Oct 5, 2021 at 12:32
  • \$\begingroup\$ Oh, I've forgot to mention that I'll use 78L12 LDO to power NE555. \$\endgroup\$
    – Mr D
    Oct 5, 2021 at 15:32
  • 1
    \$\begingroup\$ If you would use 12V linear voltage regulator for powering the NE555 why would you think you'll need to "protect" a MOSFET? \$\endgroup\$
    – NStorm
    Oct 5, 2021 at 15:55
  • \$\begingroup\$ @NStorm, so if I'm using LDO to power NE555, then I'm also limiting it's output to MOSFET. Actually, I haven't thought about it. \$\endgroup\$
    – Mr D
    Oct 5, 2021 at 18:49

1 Answer 1


The zener will be useless as you seem to be powering the NE555 with 12V, so you don't need any protection for FET gate.


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