The simplest solution would be to use a logic-level-mosfet such as the 2n7000.
In many cases this is sufficient by itself, Gnd the Source, connect Gate to pic pin (direct works but if you want to be certain you could use a 470 ohm resistor in series).
Drain can either be connected to the load with load connected to the appropriate level,
or if more current is needed connect a pull-up resistor to 12v+ and use that to drive a larger mosfet.

KF4HAZ - Lonnie

----- From: "Hector Martin" <hector@
> Hi all,
> 
> I have a simple question regarding MOSFETs (this is the first time I
> use one): what is an appropriate MOSFET driver for controlling it with
> a PIC? I want to use an IRF510 to PWM some (relatively) small loads
> (fans and similar stuff). I was thinking about a simple BC847 driving
> the gate to +12V, but I'm not sure what is really needed (the +5V-ish
> that the PIC spits out is too low for gate voltage I presume, since it
> is quite close to the threshold and will probably increase the
> resistance). Do I need a resitor on the gate? How should I protect the
> PIC from MOSFET failures?
> 
> Cheers,
> -- 
> Hector Martin (hector@marcansoft.com)
> Public Key: http://www.marcansoft.com/hector.asc

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