Red LED as MOSFET protection diode?

[MikeH]

The Matchbox project at ROG has a Red LED across the gate and source of the BS170 MOSFET, where you'd usually see a 1n4001 or a 9V zener.  Is this acting as a protection diode, and if so, is it effective?  Any pros or cons to this setup?  And does this mean you can throw pretty much any diode in there for protection?

[John Lyons]

I don't know the particulars but yes, it's a protection diode.
I've only seen 9v zeners and Red LEDs there...

John

[amz-fx]

There are probably 10 or more chemistries of LED composition with different characteristics... LEDs usually have a reverse breakdown rating of 5 V minimum and 15 to 25 V typical,  which is way too high for proper protection of the mosfet.

Put what you like in the circuit, it's probably okay with no protection, but I'll stick with the zener.

regards, Jack