[sdiy] <no subject>

[Seb Carr]

Hi, i've been silent on the list for a bit, just reading and learning, and
feel ready to start on something.  While sometime i rckon i'll probably
build an oakley modular, i don't want to straight away as i'm a novice, so
i'd like to start more simply.
    Using the idea "stick to what you know" i was considering making an VCO
from using a 555, as the 555 circuits i know are very simple and i've read
that the 555 is very stable.
so does this mean that its tuning shouldn't drift too much? I believe that
the PAiA fat man uses the 555 for its vco section and i believe it outputs a
saw waveform, but the circuits i'm familiar with output square. How do you
get different waveforms?
    I was also wondering if anyone has any simplke but functional vco
schematics for the 555.
    Sorry to add another PSU question, but all the 555 circuits i know run
happily from a 9v battery but everything on this list appears to be a 12v or
15v bipolar. Why is a bipolar supply such an advantage? Are the bipolar
regualted supplies from maplin ( i believe they sell a quite cheap hobby
one) any use or do i have to build one? If building should a use a normal or
toroid transformer?
    Thanks for any help

Seb Carr