"Roy J. Tellason" bravely wrote to "all" (07 Jan 04  20:16:25)
 --- on the heady topic of "bag of chips"

 RJT> While sorting out some "stuff" I came across this bag of chips...

Yummy!


 RJT> It was still stapled shut,  so it was apparently meant for something.
 RJT> I don't know if this was a part of an assortment sold as such,  just
 RJT> an assortment of parts,  or if it was meant for some particular
 RJT> circuit.  I suspect the former as it resembles a number of bags of
 RJT> quarter watt resistors I encountered a while back during another
 RJT> session...

Awww, not the edible kind of chips... :-(


 RJT> Anyhow much of what's in there is pretty generic stuff.  Two things
 RJT> stand out though.
 RJT> One is a chip resembling an op amp,  but apparently preconfigured as a
 RJT> unity-gain buffer.  I found it easily enough in my databooks, though I
 RJT> don't know why you'd get these and not just use a standard op amp and
 RJT> configure it as a unity gain part.  Maybe some difference in the spec
 RJT> that's not apparent to me,  or something...    (Anybody know?)   I
 RJT> suppose I'll think of something to do with these sooner or later.
 RJT> The other part that jumped out at me as being a little unique was a
 RJT> 565 PLL chip.  I have heard of this one before,  but have *no* idea
 RJT> what you'd do with it.  Any of you guys have any thoughts on the
 RJT> matter?

I think that PLL was part of a series of chips (IIRC 564, 565, 566)
which were intended for various frequency ranges and uses. I think the
566 & its cousins was common in project magazine FM radio SCA
projects to decode 76KHz (?) subcarrier transmissions. One was also
used in DTMF decoder projects but with today's technology it would be
a waste of time building as we now have this function in a single
decoder IC. I remember seeing those decoder projects, they used tons
of parts to make the filters using first opamps, later the 565 PLL's,
and finally a single IC. The original Bell labs used a really
complicated switch to connect coils in various configurations to get
the dual touch tones. I still have one of those early push button
switches. What a nostalgic bit of technology. It seems even quainter
than vacuum tubes. The analogy sort of like electronics as imagined by
a plumber. Perhaps you have a project kit to build a 565 tone decoder
to turn on a lamp using the telephone or something like that? :-)

 Mike
 ****

... I worked hard to attach the electrodes to it.
--- Blue Wave/DOS v2.30