[sdiy] Low current power supply?

[dj hohum]

A little experimentation suggests that a 0.3 mf cap in series with a
typical 1-1 isolation transformer will give me about 12v. It seems to
run my circuit just fine.

http://www.aaroncake.net/circuits/supply5.asp?showcomments=all

So to be clear. All I have going is a cap in series with the AC line
feeding an isolation  transformer taken from a modem. The output is a
standard non-regulated power supply.

Any criticisms, comments, things I should concern myself about? I've
seen this idea from days gone bye I just couldn't remember where and
it's difficult to search for.

tnx,
Daryl


On 7/16/07, dj hohum <djhohum at gmail.com> wrote:
> On 7/16/07, Paul Schreiber <synth1 at airmail.net> wrote:
> > >
> > > I have found this which could be easily adapted for the correct voltage:
> > >
> > > http://www.imagineeringezine.com/PDF-FILES/acdc1.pdf
> > >
> >
> > Holy crap! Talk about a wideband noise generator :)
>
> Yeah, I thought about that. I've seen similar ideas before and was
> hoping someone had seen something cleaner, or even  simpler.
>
> > Before you go off and zap yourself,
>
> I've been working with high voltages for years, I'm not worried about
> zapping myself.
>
> >look at spending $34 for one of these
> > things:
>
> > http://datasheet.astrodyne.com/PWB.pdf
>
> Those are almost what I need. If the both the price and available
> output current were much lower, they'd be perfect.  In fact I have a
> few old modules very similar to that in my junk box. Once you hit
> 100ma or so the circuit is usually complex enough to justify a small
> traditional power supply. I would like to find modules like that for
> about $5 that provided about 10ma.
>
> This is closer to what I had in mind:
>
> http://www.electronicproducts.com/ShowPage.asp?Section=3130&PRIMID=&FileName=novhl11.nov2000
>