# [sdiy] What's wrong with this picture?

Theo t.hogers at home.nl
Sun Jun 23 14:07:46 CEST 2002

```You may use two 9V batteries in series.
The center between the batteries becomes the "GND or 0V" or better
"reference voltage".

Alternatively you can setup a divider using two 1M or so resistors between
9V and  0V and buffer this voltage with a opamp.
This 4.5V becomes your reference voltage.
However gnd for you incoming and out going signals stays the 0V.
Therefore you need to   AC couple your circuit to the outer world.

HTH
Theo

From: Hallvard Tangeraas <northstar2010 at yahoo.no>

> At 23:34 +0200 22-06-02, René Schmitz wrote:
>
> >The circuit needs to be run from a bipolar supply. You tied ground
and -15V
> >together.
> >This won't work.
>
> Bipolar power supply? You mean like +15V, -15V and 0V?
> I tried running it off a 9V battery (thinking this should work since the
> operating range of the TL-082 is 4-15V and the LM-741 is 5-18V).
>
>
> >(Pin 5 and 4 are tied tothether on IC 1, break up that
> >connection,
>
> OK. No problem.
>
> >and
> >use the trace in the middle where the R2, R6, and the diodes meet as your
> >GND.)
>
> In other words:
> After separating pins 4 and 5 of IC-1 (TL-082), should I connect pin 4 of
> the same IC to -15V and leave the rest as it is (connected to the "-"
power
> supply pin, but instead feeding 0V/GND to it?).
>
> What about IC-2 (LM-741)? Should I remove pin 4 from the GND tracks on the
> PCB as well, and instead connect it to -15V?
>
> Is there any way I can use the circuit with a battery (i.e. a 9V battery
as
> mentioned above)? Alternatively I can use the vocoder's power supply as it
> has +12, -12 and 0V lines.
>
> Thanks for looking into it!
>
>
> Hallvard
> --
> Notator/Creator SL : <http://www.notator.org>