V G wrote:
> Would a VN2222 N channel MOSFET be suitable? Or an equivalent in
> surface mount?

I don't know what a VN2222 MOSFET is.  The number 2222 hints at some varian=
t
of the very common 2N2222A NPN transistor.

The reason I mentioned MBT4401 is that's the NPN jellybean transistor I use=
..
It's just as cheap and plentiful as 2222A or 3906, but is rather more
robust.

> Just checked your IRLML2502. Loving the current drain capability at
> Vgs =3D 3.3V. I guess I'll go with that.

That's a very nice part if you don't need more than 20V capability, which
you don't in this case.  The IRLML0030 is close to the same thing with 30V
capability.  However, these are many times more expensive than something
like a MMBT4401, although in absolute terms its only a few 10s of cents.

Too often it seems people knee jerk to using a FET when a plain old bipolar
will do fine.

> My only concern is that the SOT23 part will be a bit hard to solder
> by hand.

SOT-23 is no big deal to do by hand.  The pins are 50 mil pitch if I
remember right.


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