[sdiy] Multiple LM317s - serial or parallel?

[David G. Dixon]

> I have an LM317 in a TO-220 package outputting 12V DC from a 15V DC
> supply.
> 
> I have a second LM317 in a TO-92 package outputting 5V DC and a third
> outputting 3V.
> ...

Just out of curiosity, what are you running with the 3V regulator, and why
can't you just run it on 5V?  Ditto with 12V, why can't you just run it on
15V?  It seems like an awful lot of trouble to have four separate voltage
sources in a circuit!