[sdiy] Re: 4049 and 4069

[Scott Gravenhorst]

"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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