> 1) The 7805 is actually a Motorola MC7805CP, date > code 7308 with gold leads. Very hard to exactly > replace.
Is that the big flat plastic package with the wide flat leads? I might have a few of those around, but I agree, not an easy variant to find. > 1) I have a 12 volt DC supply. 12 volts seems to be > within the VIN range for the 7805s whose data > sheets I've now read. Can I simply apply 12 volts? Yes, but that regulator might get mighty hot! I would not do this for fear of cooking the poor thing. > 2) Could I place a resistor in series between the 12V > supply and the 7805 to drop the voltage at the 7805 > to somewhere around 8? Yes, you could do this. Pick an appropriate power resistor, or use a big wirewound rheostat. > 3) If I was to "tack on" a jumper between VIN and VOUT, > would that protect the 7805 and allow me to power the > circuit with 5 volts? I would not do this at all. -- Will
