In article ,
Dave Plowman (News) wrote:
In article ,
Paul wrote:
That's a dual op amp which seems to take high rails
voltage and is intended for driving 600 ohm or 2K ohm loads.
The 600 ohm value, I gather, was a telephony headphone
value of long ago (suited to the vacuum tube era perhaps).
I might have had such a headphone at home when I was a kid.

It's the output impedance of a cathode follower valve. The lowest
impendence then without using a transformer.

Thinking back to my BBC training many many years ago, it's also the
nominal impedance of a pair of overhead telephone wires reaching to
infinity. ;-)

--
*Why isn't 11 pronounced onety one? *

Dave Plowman London SW
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