-=> JASEN BETTS wrote to ROY J. TELLASON <=-

 RJT> One is a chip resembling an op amp,  but apparently preconfigured
 RJT> as a unity-gain buffer.  I found it easily enough in my
 RJT> databooks, though I don't know why you'd get these and not just
 RJT> use a standard op amp and configure it as a unity gain part.
 RJT> Maybe some difference in the spec that's not apparent to me, or
 RJT> something...    (Anybody know?)   I suppose I'll think of
 RJT> something to do with these sooner or later

Designed for better wideband response at unity, not so easy to
achieve. Also to reduce output impedence which can alter
the linear response and behavior of subsequent circuitry.

 RJT> The other part that jumped out at me as being a little unique was
 RJT> a 565 PLL chip.  I have heard of this one before,  but have *no*
 RJT> idea what you'd do with it.  Any of you guys have any thoughts on
 RJT> the matter

A fairly low frequency demodulator chip IIRC.
Likely about the same as you could with a CMOS 4046 which I've
more experience with.
Built a Hi-Fi audio link that used a 4046 PLL at either end.
Got well over 1,000 feet range with just a LED and a 3" glass
lens at one end and far smaller lens at transmitter end.

 JB> ISTR that a PLL is a kind of frequency follower, other than using it in
 JB> a frequency synthesiser (in a radio tuner) or frequency multiplier etc
 JB> I don't know what you could do with it,

 Provides a voltage output from it's filter that's proportional
 to it's center frequency and incoming frequency.             
 I used this in my lightwave communications link feeding the voltage
 follower on that filter directly into an audio amplifier.
 Remote telemetry is another use such a circuit suggests to me.

 The filter supplies the voltage that drives the tracking VCO
 and that filter must be responsive enought to keep the phase
 shift between input and VCO between limits or
 the phase lock loop loses lock.

 The 4046 I messed with had stable lock at 90 degrees of
 shift between input and VCO and could go to just shy of
 zero or 180 degrees before losing lock.

 JB> HMM, maybe you've got a parallel-port radio tuner kit there.

 -=> Bye <=-

 JB> ---
 JB> (3:640/1042)
 
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