Greg Mayman wrote in a message to Roy J. Tellason:

 -=> Roy J. Tellason said to Greg Mayman
 -=> about "BAG OF CHIPS" on 01-22-04  04:07.....

 RJT> Yeah,  I remember seeing them and thinking "Now I don't have to bother
 RJT> with _THAT_ any more...!"

 GM> Yup. Me too!

 RJT> In those days I was a little fuzzy about what slew rate implied.  :-)

 GM> So was I. I knew it had something to do with increasing distortion
 GM> at high frequencies, but I didn't really start to understand it
 GM> until I actually saw it on a CRO.

 RJT> They were still useful,  though.  And really,  how often do you need
 RJT> that wide a voltage swing in most stuff?  I can remember running into
 RJT> it fairly seldom, the one big exception being in early analog synths
 RJT> where a 10 volt p-p waveform wasn't all that uncommon.  Most audio
 RJT> stuff is at a lot lower level, until you get into power amp stages.  I
 RJT> guess this is of more concern with other uses...

 GM> We designed a lot of broadcast studio gear using 741s and the twin
 GM> version 747.

I actually ran across one of those around here recently.  :-)

Dunno what the difference is between that and the 1458, 5558, whatever the
heck it is.

 GM> They were running at a nominal 100mV RMS, and at the peak rating 
 GM> of the equipment, the level was only about 3v peak to peak on 
 GM> those stages.

Sounds reasonable to me.

 GM> The level had to be kept low as we were using FET switches, and
 GM> when the signal got too high it would turn them on and break
 GM> through on peaks. That was back in 1970 and was our first effort at
 GM> using integrated stuff.

I think I may go to AC coupling next time I start messing around with those
4066 chips.  I was going to try split supplies,  but then you need a +5/-5
logic swing for the control voltages and I'm not sure I want to go there.

 GM> The low level stages used Fairchild 739(?) low noise op amps that
 GM> had a single-ended output. IIRC we had to follow them with a 741 to
 GM> get low enough output impedance to drive the 10k faders.

Oh really?  That's pretty bad,  10K isn't that much of a load.

 GM> We used the same op-amps in the high level stages as that single
 GM> ended output was ideal for driving a complimentary output pair of
 GM> transistors.

Or you could just arrange for an inverted output as well as the normal one
to provide a balanced signal.  Maybe that's what I'll use those chips
for...

 RJT> So it'd be good for picking up a weak and distant station that was
 RJT> close in the band to a stronger and more local one?  Interesting stuff!

 GM> Yup. Although you have to watch out that the adjacent channel 
 GM> doesn't cause overload and intermod distortion in the IF strip if
 GM> it's much stronger than the signal you're trying to pick out.

You still need some selectivity in the front end,  I guess.

 GM> I have an article about the advantages of sync detectors in HF
 GM> communication receivers in a "World Radio & TV
Handbook" from a few
 GM> years ago, but it is 2 1/2 pages of fine print so I won't attempt
 GM> to type it up here.

Do you have access to a scanner?  :-)

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