-> was done with high powered versions, great howling monsters running
-> at about 20volts, 20 000 amps. Brown Boveri *I think* made these.
Great googly wooglies, Alec!  That's some huge rectifier!  What
frequency did it run?  Didn't the rectifier contacts take a beating?
-> currents caused corrosion of pipeline and phone cables. This
-> amplifier allowed a standard 1mA ink recorder, to put the streetcar
-> traffic cycle patterns to paper.
We have similar instruments in use in the oil patch and along the miles
and miles of natural gas transmission pipelines.  Also lots of
sacrificial anode power supplies run off the power mains with stepdown
transformers and silicon rectifiers now.
-> My first *real* auto radio was a British made hybrid- a few valves
-> and a few transistors. The valves were driven at about 200v dc from a
-> vibrator like you describe, 12v synchronous hummer with contacts on
-> both the primary and secy sides of a step up trannie.
Lord, Alec.  You aint as old as I thought. The ones I'm talking about
were in the late 30's and early 40's cars.  NO transistors of course and
the 6 volt tubes drew about 7 amps of heater current, plus whatever the
vibrator and B+ system required. (Normally about 250 Vdc @ 3-500 ma.)
The OZ4 was a tiny little gas dual diode.(About an inch high Octal) that
was firmly overstressed and thus had a VERY short lifespan.  Lots of us
car radio guys practically made a living changing the little boogers.
This was in the '50's and early 60's.
-> Have you heard of the Man Machine? Or the Biological Engine?
Nope, but we have a very similar man lift machine that we use in grain
elevators where you just jump on or off depending on where you are and
where you're going. (One side is UP and the other side is down.)
The other thing is too gross to consider!  I'd just as soon never have
KNOWN about it!  
-> voltage variations etc etc. Any change in tension would cause the
-> tube to swing, and the grid to move causing a a rapid change in tube
-> gain, and fire up the contol fields of the [DC] main drive motor to
-> compensate.
Again we have a parallel.  Gas thyatrons used to control the bending of
wood being formed for church pews.  The swinging grid is replaced by a
similar but mechanically more stable magnetic field.  Works the same
though....
-> the Genesis of such a lot of current science, that we imagine got
-> dreamed up in Silicon Valley!
Yep!  Just old technology with new names and faces.  (I hope nobody
ressurects the OZ4 though......)
 ^..^
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