Before electronic counters, like the
HP vacuum tube neon 500 series that used the
AC4A
decade counting module analog mechanical methods were used.
This
prrticular model is DC powered and counts in milli seconds.
The
6,000 RPM (100 Rev/sec) 27 VDC motor is geared down by 50 times so
the
fast hand moves at 2 Rev/sec. The slow hand counts in half
seconds up to 15 seconds.
There are 4 electromagnetic components:
- The DC motor with a govener
- The clutch
- Two relays
The instructions say to let the motor run for three minutes before
making a measurement. Depending on how the two toggle
switches
are set you can make different types of measurements. With
both
switches off the clutch engates when +27 volts is on terminal "I"
and
stops when the input stops, so measures pulse width. With
both
switches on the timer starts like before, but the relays latch and
hold
so the timer keeps running after "I" goes low. It stops when
input "II" goes high thus making a time interval measurement.
If you know of any applications where these were used by the Air
Force (Army Air Force?) or have a manual please
let me know.
Although made in 1951 it still functions, although I haven't
checked
the calibration. It makes a sound that I remember hearing in
movies, maybe of atomic bomb tests or some other scientific
experiment. It has a distinctive sound.
There is some type of soft fuzzy off white substance on some of
the
shiny metal surfaces. For example the zero lever going from
the
lower left post up and to the right is completly covered with
it.
The screw in the lower right has it's head covered. The
screws on
the back of the relays are shiny and clean. It wipes off
easily,
but if not cleaned will come loose and get on the dial or other
parts.
I think it's possible to dissassemble the clock work while leaving
all
the electromagnetic items connected to thier wires. That
would
allow cleaning the mechanical parts and putting fresh modern
lubricants
on.
If you have any maintanance information
let
me know.
