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Cgs synth

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Re: CGS33 Matrix Mixer Basic Circuit Questions

2007-03-12 by bbluthang

--- In cgs_synth@yahoogroups.com, "peng3002" <peng3002@...> wrote:

> The first schematic is the buffer stage. I've built many a buffer
> stage like this except without the 1K resistor. What purpose does this
> 1K resistor serve?
>
I assume the 1k/100k were there to provide a hi-Z input, as Ken wrote
- " Any signal applied to an input is first buffered by a voltage
follower based on a TL071 op-amp so as to not load down the output of
whatever module is driving it. "


> My question is: What are the parallel diodes and 4.7K and 390R that
> are in the lower feedback loop doing? This is very interesting.
>
this was asked a few weeks ago -

">What do the diodes do in the CGS33 matrix mixer? Do they prevent
>signal overload (limiting)?

Yes, they are a little clipper on the output amp. They and their
associated
resistor divider can be omitted if desired."

hope this helps a bit
andrew

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