William Donzelli wrote: > > 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?
Nope, purple ceramic. The heat transfer plate is gold plated too. > > 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. That's what I figured to start with, before reading the datasheets. > > 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. At this point, I think I'll just wait till Monday and work on other things. > > 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. I didn't think so. Bill
