Hello
folks,
This past February I picked up a unique instrument, an
LA800D WWV comparator, at a hamfest. Ever since then
I've been fascinated by it
-
one might say obsessed. The instrument in question
has a small CRT in it, which it displays a circular
pattern drawn by the beam
being
deflected synchronously with the WWV-derived
frequency. The intensity of the beam is modulated by
a user-provided frequency. The resulting
display
is that of a semi-circle which is stationary when the
user's frequency is the same as the WWV frequency. As
the user's oscillator drifts,
the
semi-circle begins to turn at a rate proportional to
the frequency error. It's a fascinating and
brilliantly elegant use of an
instrument-integrated
CRT.
This got me to wondering about what other sorts of
"non typical" CRT displays might exist out there and I
thought I would mine the HP and
Tek
groups's expertise for suggestions. Can anyone
suggest other instruments which have an integrated
CRT, but use it in a manner OTHER THAN
then
the usual Voltage vs. time of an oscilloscope?
Alternatively, if the x-axis is time, is it
integrated in some unique way?
I list below some examples that I either own or that I
have found, that fit into this category. I'd like to
expand the list.
1)
FR-4/U frequency meter part of AN/URM-79 or AN/URM-82.
An example is here (no affiliation):
I actually have one of these things. I can't
remember where I got it though. This is a really neat
instrument. The gist of it
is
that you mix an incoming frequency with a harmonic of
a 1.25 MHz crystal oven-derived source. After setting
up a Lissajous pattern on the
small
built in CRT, you look up the dial settings in an
attached book to get the frequency, accurate to 1 part
in 10^5. It covers 100Khz to
20
MHz.
2)
A similar example is probably the HP 100C and 100E
oven-stabilized crystal oscillator. These had
built-in CRTs to display the
dividing
ratio in Lissajous patterns.
3)
the only example of an integrated X-Y scope that I
have is one I built myself based on the Amateur
Scientist in the May 1963 issue of
Scientific
American. In this case a pair of crossed loops picks
up the impulse generated by a lightning strike and
displays them on the
x-y
axes of a scope. The z-axis is modulated by the
detected electric field so you get a vector in the
direction of the strike.
4)
I've recently been turned on to the
integrated-display Quad receivers, of which the
Marantz 4400 is the epitome.
acts
as an x-y scope to display the outputs of each of the
4 speakers, but can also be switched to tune the
receiver, so it
serves
as a simple spectrum analyzer.
In
later receivers, the separate box was integrated into
the communications receiver chassis, but either way it
counts.
Essentially,
these are spectrum analyzers with the displayed center
frequency tuned to the receiver's frequency.
I'd
love to have a Panalyzer with a 455 KHz IF to hook up
to my standard AM/FM receiver.
...I
think that's a CRT in there, though I am not sure how
this thing works. I am presuming that the HV for the
CRT comes from the spark itself.
7)
Loran Receivers - I know some of these had built in
CRTs. I am not sure what they displayed exactly. Too
bad Loran has been silenced.
8)
chuck Harris pointed me is this direction - the very
earliest computer systems used a CRT to display the
innards of the computer's operation.
Connect
a DAQ to the address bus and display it on the X-axis
and another DAQ to the data bus and display it on y.
The resulting display will
show
which addresses are accessed most frequently and if
the program is stuck in a loop, the display will
literally show a loop on the screen.
The
middle CRT appears to be the output of a Williams
tube, but the other two appear to be displaying
address space on the X-axis.
It
seems this would be an awesome project for something
like an IBM PC.
10)
RADAR - certainly a non-typical display. One example
that comes up a lot on the net is a reconstruction of
a German RADAR,
...which
has very detailed descriptions of the various circular
scope traces.
11)
??
Does
anyone know if line CRTs (i.e. CRTs with only one
deflection axis) were ever used for something other
than scanning documents?
I'm
curious to hear what other suggestions folks may have.
Dan
