2005-06-25: The circuit diagram contains a minor update
compared to the original diagram form the article379.
The diode D2 is now between +out and -out instead of
+out and gnd.
The previous connection to gnd had the disadvantage that
circuit (the atmega8 to be precise) was only protected
reverse current up to 1A. That is you mistreat the powersupply
and connect a stronger external powersupply to output
with opposite polarity (incorrect polarity) and a current
higher than 1A.
I know that this is not a very common use. It is up to
you if you want to apply this change. 


