Odp: [sdiy] uA726 transistor array

[Roman]

----- Original Message -----
From: Magnus Danielson <cfmd at swipnet.se>
To: <harrybissell at prodigy.net>
Cc: <cxh02175 at nifty.com>; <synth-diy at dropmix.xs4all.nl>; <miketina at tpg.com.au>
Sent: Sunday, October 13, 2002 1:48 PM
Subject: Re: [sdiy] uA726 transistor array


> Jörgen Bergfors reported to me in a private email-session that he noted that
> the LM311 comparator where a source of thermally induced frequency shift. This
> is logical since the comparator is used to detect the phase-ramp against some
> stable level. The comparator core is another diffrential transistor-pair, so
> we should not be supprised.

My datasheets don't specify temperature drift for LM311. I assume Vos is
the bad news here. It only say 10mV over 70 deg range. So 10mV/70deg
is 142uV/K. Frequency is linearly dependent on comparator threshold, so
at 5V ramp its 28ppm/K. Quite good for a cheap bastard. OTOH precision
opamps have that drift about 100 times lower.
I mean, what are other bad news about LM311 except Vos drift?
I just bought a bunch of them so I don't know if not to use them as
frutalizer for my plants now. Jorgen? Anyone?
Maybe it's varying response time and slew rate too?

Roman