[sdiy] Re: 4049 and 4069

[jhaible]

My 2 cents:

Yes, wonderful soft clipping from unbuffered CMOS. But also
a little noisy. I wish I had such complementary MOS transistor
pairs in a low noise version!

15V (or /-7.5V) is what the chips can take, but the gain is
much higher at low supply voltages.

JH.

-----Ursprüngliche Nachricht-----
Von: Scott Gravenhorst <music.maker at gte.net>
An: <synth-diy at dropmix.xs4all.nl>
Gesendet: Montag, 19. Januar 2004 19:11
Betreff: [sdiy] Re: 4049 and 4069


> "Shokwave" <shokwave at nb.aibn.com> wrote:
> >
> >----- Original Message -----
> >From: "harrybissell" <harrybissell at prodigy.net>
> >
> >> The 4049 may not work as well in linear apps as the 4069.  The
transistors
> >> in the 4049 are not a matched pair... they can (iirc) sink much more
> >current
> >> than they can source.  The one time I tried a linear circuit with them,
it
> >> oscillated
> >> at the crossover point... causing me to have to redesign the whole damn
> >circuit.
> >
> >Well, thanks to Peter Snow being an awesome fellow, I have a few 4069's
as
> >well! Anderton used the 4049 for his "tube-sound fuzz"...I wonder what a
> >4069 would sound like in there. I think I'm going to find out :)
> >
> >Of course, the fact that they AREN'T matched probably contributed to the
> >tubish qualities, shaping the waveform different above and below the 0v
> >line. Isn't it odd, I seem to find myself looking for components with
> >inexacting, "flawed" characteristics a lot (re "hunt for vactrols",
"oooh, I
> >found  j201's for cheap" etc). This is fun.
> >
> >-Darren
> >
>
> Darren,
>
> I've done some work with the 4069UB (I don't know if there is a buffered
> version of 4069 at all, if so you don't want it for use as a linear
> amplifier) and one thing I did notice about it (in linear amplifier usage)
is
> that it's gain deteriorates as it's output approaches either supply rail
(Vss
> or Vdd).  It does this in such a way that looks to me like it mimics, to
some
> degree, the soft clipping of a tube amplifier.  So I imagine that a 4069UB
> might make a nice "tube distortion sound" device.  I've not tried *that*
per
> se, but I have used this fact in a tri to sine shaper to round things a
bit.
>  Under these circumstances, I got a very nice sound, very sine-like.  I
doubt
> that it was a perfect sine, however.
>
> Also, one thing to remember about using either 4049 or 4069 in linear amp
> mode is that the IC will draw more current than is spec'd for logic use.
> Bear that in mind when designing a supply for it.  They also get slightly
> warm.  The lower the operating voltage, the less current and heat.
>
> These parts can also be used with a dual supply, spec says maximum of 15
> volts (but an absolute maximum of 18) between Vss and Vdd.  This means
that
> +/- 7.5 stays within the strict spec advice, however, I've used +/- 8
volts
> with no problem.
>
> Please keep us all up to date on anything you try!
>
>
> =========================================================
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>
>