4 Sep
2006
4 Sep
'06
4:12 p.m.
I would
seriously recomend against rectifying the mains for something
like this. Non-isolated PSUs have the nasty habit of making things live
that you least expect, and may kill you (or worse, damage a classic
computer).
Oh, I wasn't suggesting that, simply pointing out that once you got your
isolation a simple rectifier would do the trick just fine...
I've had my experiences with non-isolated equipment, more than I ever wanted,
and don't plan to build any to add to that. :-)
Me too. I grew up fixing series-string radios and TVs (until the coming
of 'baseband' audio and video sockets, such as the SCART connector, most
TVs sold in the UK, even semiconductor-based ones, had a live chassis). I
don't much care for working on such units.
What amazes me is that in the 1950s and 1960s, UK magazines published
several educational courses. Typically you'd start by building a crystal
set, then turn it into a 1-valver (leaky grid detector), then add audio
stages, RF stages, and maybe end up with a superhet.
Thing is, you got the HT (B+) by half-wave rectifying the mains. The
exposed metal chasis was connected to mains neutral. And you had
headphones. You know, that could easily turn into an electric chair...
If you use back-to-back transformers as I've
suggsted, the actual voltage
got get out depends on the turns rations, of course. Maybe a simple
rectifier will be enough, maybe you need a doubler.
Many suggestions that I've seen illustrated like that suggest using two
identical transformers, which should get you the same thing out as you put
in.