Positive voltage converter.

[stewart pye]

> Reverse the polarity of caps and diodes (and other components as needed)
in
> the charge pump. Consider the concept of the charge pump as distinct from
> the specific circuit. There may be other odd changes needed.
>
> OR
>
> Use a second bridge rectifier off the transformer, but connect it to the
> transformer through some bipolar capacitors. The rest of the circuit would
> be pretty much as per a standard regulator.
>
> Of course I haven't looked in the synth in question, so there may be other
> issues.
>
> Ken
>


The CS10 is powered from a DC plugpack or batteries so the second option
wouldn't work in this case. At looking at the schematic and PCB again, I
think if I change the output socket GND to V- and the output pullup resistor
to a pulldown the whole synth will look a lot more like a standard gnd
referenced single positive supply device. (The schematic looks unusual
because the gnd symbol is where V+ usually is and V- is where gnd usually
is, however the output gnd is the same as cct gnd which is actually +9V.)
The pullup is after a bipolar cap on the output of an emitter follower so if
I connect that and the output gnd to V- it should be ok, right?

Did anybody follow all of that!? sorry I couldn't explain it more concisely.
This is what it looks like now.....

             1                     3
            ----[7809 reg]--------- gnd
                          |2
                          |
                          V-

                     gnd________output sleeve
                        \
                        /pullup
out signal ____\_________output tip



Thanks for the replies.
Regards,

stew.



> >Hi All...
> >
> >Some of you may remember me, I've been on the list for about 4 years but
> >haven't been active for a while. Anyway, here's my problem....
> >
> >I'm doing some mods to a CS01 and have found that it uses a "psuedo
> >negative" power supply. That is: the output of a 9V reg is used as ground
> >(including the output socket) and gnd form the reg is used as V-. This is
> >fine until you want to interface other stuff to it.
> >
> >I need to derive a positive voltage with repect to the CS01 gnd so I can
> >power op amps to invert control voltages and such. All the charge pump
IC's
> >I've seen only do positive to negative conversion.  Any ideas???
> >
> >
> >Thanks,
> >
> >Stewart.
> >
> >
> >
> _______________________________________________________________________
> Ken Stone   sasami at blaze.net.au
> Catgirl Paradise <http://www.anime.net/~kens/>
> Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>
>