ok, i was trying to use the lf444 quad op amp,,,, and i couldn't get a
single thing to happen other than some crummy low end noise.

perhaps i'm not biasing something correctly,,, i am new to electronics
theory and am only just now getting into more hands on things.

i didn't implement any caps inline with the lf444, i was simply
following the basic circuit listed on the pa381 data sheet.....

yes, more help is greatly appreciated, especially if you could show me
how to do this using the lf444 chip instead.

thank you very very much!


--- In Doepfer_a100@yahoogroups.com , "Tim Stinchcombe" <timothy@t...>
wrote:

>
> To do this looks relatively straightforward. The PA381 is a current
> output device: the currents output from pins 1 & 7 of both chips all
> come together at one end of J1, and are summed by one op amp in the
> TL082 - pin 6 is the summing junction, pin 7 the o/p, pin 5 grounded.
> So you would have to replicate this op amp set-up - a 47k feedback
> resistor, 22p stability cap (C13) and 1k o/p resistor - for each
> section. The second op amp in the TL082 is unused, but it would
> probably be easier to use a TL084 on a separate piece of
> stripboard/whatever.
>
> It's getting late in the UK, but I can maybe supply more help
> tomorrow if needed!
>
> Tim
>
> --- In Doepfer_a100@yahoogroups.com , "danv_83" <danv_83@y...> wrote:
> >
> > Hi,
> >
> > I was just playing around with the a-135.
> >
> > I basically want to be able to make seperate outputs for each
> channel
> > after the cv attenuator circuitry. I am having trouble figuring out
> > exactly how the circuit works - I was thinking that the final stage
> > before each channel's signal get summed and then led through the
> > makeup gain ic and then to the master out - is on the pa 381 ic. So
> my
> > plan was to just tap the seperate outputs from the two pa381 ic's
> and
> > then lead each channel into it's own seperate makeup gain opamp,,,,
> >
> > So I tried this but wasn't getting any signal.... I'm sure if I
> could
> > see the schematics I could make better sense of everything,,,,
> anyhow
> > I am hoping somoene can offer some insight on how to actually do
> this.
> >
> > It would be great to have the seperate outs,,, would be like have an
> > extra 4 vca's available!
> >
> > Thank You!
> >
>