Maxim MDS-500

[Peter Snow]

Colin,

I certainly intend to check this out when I get more time. Perhaps I can sub 566's (quite
a bit of work I would guess) and use the 2044's for something else!
But I am still puzzled that the manufacturer would use an "expensive" chip (both price and
real estate - 16-pin) to produce a tone that could be done as well by a smaller and
cheaper chip.  Or perhaps it was essential that they used a sine wave instead of, say a
triangle wave? I dunno...

Cheers,

Peter




Colin Fraser wrote:
> 
> ----- Original Message -----
> From: "Peter Snow" <psnow at magma.ca>
> To: "Synth DIY" <synth-diy at node12b53.a2000.nl>
> Sent: Monday, January 01, 2001 11:38 PM
> Subject: Maxim MDS-500
> 
> > Now the problem is that one of the channels does not produce a tone -
> noise and click work
> > OK though, so I suspected a bad tone generator chip or perhaps a VCA. But
> when I opened it
> > up, I find it is full of SSM2044 chips.  Aren't these VC low pass filters?
> There are no
> > filter functions on this unit so what are these chips being used for?
> Surely they are not
> > being driven into oscillation to use as VCOs? If so, seems like big
> overkill when
> > something simpler could have been used, like a 566...
> 
> Don't have a schematic or anything, but a 2044 would be a minimal part count
> solution for a vco with a pure sine output.
> This is even suggested in the datasheet.
> If you follow the output pins on the 2044s, you should find they are
> buffered by an op-amp.
> Hook up a scope to the op-amp outputs and you should see what they are
> doing.
> If there is no signal connected to the 2044 input, then it is certainly
> being used as an oscillator.
> The datasheet is at synthtech.
> 
> Colin f