[sdiy] power supply qeustions

[Sven Windisch]

hi there

i've got some questions about this [1] power supply.

1) which voltage should the ac->dc transformer output? the datasheets for
those regulators (78xx and 79xx) sais, one should use 35V max for output
voltages from 5 to 18V. So, could i use everything between 5 and 35V or
are there some advantages for a specific voltage?

2) i know, that the ground-sign right of the diodes must be connected to
the ground-sign left of them. but what is this connected with? i've got
one of this little blue transformers they sell at conrad (don't know any
manufacturer). they just have 2 input and two output pins, no connector
for the ground.

3) how much VA should such transformer do? i know, it depends on the count
of modules. is there some thumb-rule about the relation of watts per
module? ;)

i just found one in my
stomp-in-all-electronic-thingies-that-could-be-useful-in-future-box.
(article no. at conrad.de is 506079 ) it outputs 15V with 1,5VA. is this
useful for, let's say, a sequencer, 2 vco, 2 noise and maybe a filter and
an adsr?

[1] http://machines.hyperreal.org/categories/DIY/sequencer/sneppe-sequencer/pwrsuppl.jpg

greets,
sven.

-- 
To some ears, "computational philosophy of science" will
sound like the most self-contradictory enterprise in
philosophy since business ethics.
[Paul Thagard in "Computational Philosophy of Science"]