SCADA (was Re: Help to identify a computer?)
ard at p850ug1.demon.co.uk
Sun Feb 18 12:50:47 CST 2007
> process-control equipment. I helped get me through college by
> working as an instrumentation technician summers. Really primitive
I think the main problem is that it's difficult to recreate enough of the
'process' at home to be able to use this equipment, so it would be a
static collection. Of course some meaursing instruments can be used for
other purposes, but then people do collect measuring instruments.
Not quite the same thing, but I did rescue msot of the control system
from, I think, an X-ray diffraction device. All discrete transitors,
status indicators were DM160 indicator valves, configured by a patchboard.
I got the paper tape punch and reader (mechancially the mechanisms used on
the side of a Friden flexowriter, mounted on rack panesl with their own
motors, and the printer, which was made by Victor Comptometer and seems
to be essentially an electromechanical adding machine with solenoids over
the key levers.
> stuff--your basic tools were a portable potentiometer, optical
> pyrometer and your pocket thermometer--and a pen-cleaning wire.
> A lot of the stuff was probably from the 20's. L&N Micromax chart
> recorders/controllers (used a clockspring motor to run the works;
> basically an automatic clamp galvanometer in a wheatstone bridge),
> Askania hydraulic controls. Some of the more modern stuff was Brown
> Electronik (later became part of Honeywell), and L&N Speedomax, using
> mechanical chopper-stabilized amplifiers--and the very newest stuff
I know the Honeywell-Brown 'Continuous Balance' chart recorder amplifier
with the mechnical chopper. It drives a 2-phase induction motor, of
course the output of the amplifier is phase-related to the chopper, which
is phase-related to the mains (the choopper coil was driven by the heater
winding on the mains transformer). One motor winding was driven from the
amplifder output, the other from a winding on the mains transformer. Much
the same circuit was used by various other ocmpanies, I mentioned I haf
an old Houston Instruments X-Y analogue plotter in another thread. The 2
(valved) amplifiers in that unit have mechanical choppers in the input
stage and woek in much the same way.
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