AW: [sdiy] getting +/- 12V from a 9V source

[harry]

The TL07x series has a voltage drop (max output) of about 1.5 volts less than
the rails... so thats really only a +-3V supply now. OK ???

H^) harry

Nils Pipenbrinck wrote:

> Paul wrote:
>
> > !!!!I can assure you that by the time you futz around with ".. a
> > wien-bridge sine oscillator, a fat tranny as a driver and the
> > output through two little transformers. Then add a rectifier,
> > some caps and> a 7912/7812 pair." you will be wishing you had
> > just got an  AC plugpack & done the usual!
> > Quite apart from the expense, and sourcing the components, your
> > upconverter will likey leak interference into everything & make
> > the whole project pointless, especially for a preamp.
> > Don't bother using those single chip voltage doubler/inverter
> > things either. Really!
>
> That's the reason why I asked. I had the same thought about that, but I
> wasn't sure. (besides - have you actually tried to use the voltage doublers
> for audio? They will output a noisy voltage, that's for sure, but you could
> always clean up the signal with some caps and resistors ).
>
> I think Philip's idea of just powering the opamps with +/- 4.5V is not that
> bad. I have to check, but I think my  TL072 will be happy with that voltage.
> After all it's just a RIAA preamp which I want to power, so it should work
> without changing any values. All resistors are part of the filter circuit
> and not related to the supply at all. 4.5V are plenty of headroom for a line
> signal.
>
> I just give it a try.
>
> Thanks,
>         Nils

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