[sdiy] What's wrong with this picture?

Hallvard Tangeraas northstar2010 at yahoo.no
Sun Jun 23 16:52:02 CEST 2002

Oops! Did that same mistake of just sending to the original poster and not
to the list again (I wish this list would default replies to the list
instead of the sender).

At 13:24 +0200 23-06-02, René Schmitz wrote:

>At 02:30 23.06.02 +0200, Hallvard Tangeraas wrote:
>>Bipolar power supply? You mean like +15V, -15V and 0V?

>As a first shot one can try two 9V batteries in series:
>     + -       + -
>o----| [---o---| [-----o
>+9         GND         -9

Hmmmmm.... I think I'll just stick to the power supply from the vocoder
itself as it seems a lot simpler.
But was hoping I could use a plain +/- power supply for other test purposes
when that power supply isn't available. Oh well... the oscillator is for
testing the vocoder, so it's not really a big deal.

For the rest of your instructions....
I'm getting a little confused (hard to explain electronic circuit
connections in words), but here's what I *think* you've been telling me,
which I've also shown in a new stripboard image which you can have a look
at here:


(I've coloured the 3 power lines to make it easier to track what belongs

OK, this is what I think you've told me to do:

1) Separate pins 4 and 5 of IC 1 (TL-082)
2) The power connection marked "-" (bottom left of stripboard) goes to -12V
3) The power connection marked "+" (top left of stripboard) goes to +12V
4) A new power connection is created (0V or GND). This is attached to:
   top of R2
   top of R6
   top of the two diode arrays
   pin 5 of IC1 (TL-082)
   pin 2 of IC1 (TL-082)

Have a look at the image to see what I mean. A picture says more than 1000
words! :-)
I've colour coded as follows:
0V (GND)  light-green
-12V      light-gray
+12V      red

I also removed an unused jumper wire which was previously attached to pin 5
of IC-2 (LM-741) making the circuit even tidier and prettier ;-)

>If you already have the bipolar 12V then use that. (I just said 15V because my
>psu is 15V.)

Yup, I understand. my 12V PSU should work fine within the range of the two ICs.

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