> No, you flipped R2 and R1 apparently.

OK. That makes more sense.

>  The base current is 12V accross R1
> (1Kohm) minus a B-E drop and saturated C-E drop.  Figuring 
> 750mV for B-E
> drop of Q2 and 200mV for the saturated on voltage of Q1, 
> that gives a base
> current of (12V - 750mV - 200mV) / 1Kohm = 11V / 1Kohm = 
> 11mA.  At 250mA max
> load current, Q2 must have a gain of at least 250mZ / 11mA 
> = 23, which is
> quite safe for a MMBT4403 at 250mA.

You stil have to watch the saturation, alas.
It is quite high.
You could get 250 mW or so Pd (graph reading).
Tja is high for the SMD pkg.
Maybe OK with lots of PCB copper.

A highside FET like the FDN338 would be happier but the 
bipolar will work.



        Russell

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