My Rigol will go 1000 seconds per cm, which is 2.7 hours per sweep, and you could let several traces overlap without too much confusion.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Usually not, I think. For one example, the popular Rigol DS1xxx family has sweeps that go as slow as 50 seconds/division, so you can sweep for a few minutes, but not hours.
This should be a very practical approach. The Rigol speaks SCPI (I suspect this is a popular approach) via the USB interface. You should be able to trigger a sweep every few seconds, or once a minute, or etc. and then upload as much of the trace as you want (for e.g. filtering/averaging purposes) and store the data and then plot it with e.g. gnuplot.
I did something like this a few years ago to see if the Deltron Battery Tender Jr. worked the way the manufacturer said that it did, when recharging my big deep-cycle battery. In this case I used an old HP DVM with a GPIB interface, which reads out twice a second... I grabbed the data via a Prologix serial-to-GPIB adapter, averaged 30 seconds' worth of samples, and output the result, and then used gnuplot to show the battery terminal voltage over time. The charger worked just as advertised.
Must have some impressive phosphor :) I was looking at some old CRT scopes today including a tiny Cossor not much bigger than the tube itself. I suspect a megahertz would have been too much to ask of that one.
NT
There was actually a CRT phosphor with infinite persistance.
Horrible stuff.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
It can't have produced light indefinitely, was it he one that left a darkened trace line?
The Telequipment Serviscope managed all of 30kHz. But in fairness it was never meant to be a real scope.
NT
Yes, P10 dark trace, erased with heat or UV.
Today's digital color scopes are fabulous, and inflation-adjusted about 50x cheaper than that old tube iron.
A Tek 547 with a decent plugin cost about as much as a Chevrolet.
-- John Larkin Highland Technology, Inc lunatic fringe electronics
range
.
kened trace line?
t much bigger than the tube itself. I suspect a megahertz would have been t oo much to ask of that one.
never meant to be a real scope.
Some of these people are completely out of touch with reality, which is fin e until they reach the point of being unable to assimilate new knowledge.
This little gizmo, which is kinda cheap, has a selectable acquisition rate of 1Hz, streams data in roll mode, and could allow you to record data conti nuously like forever.
More specs:
Roll Mode (Streaming Mode for Low Frequency Signals) Limited only by the computer mem ory available. Roll Mode is allowed when fs ? 1MHz and [Record Length] ? 4
s computer speed and software setting dependent.
page 16 here:
I've never met one of those in the flesh. Or in the glass. Or maybe have but it was switched off.
Progress marches on. My old Telequipment storage scope still has its place though.
NT
The Tektronix 4000 series graphic terminals used a memory-tube architecture; each lit pixel was (after activation by an electron beam) maintained by a secondary power source. The display (about a megapixel) was its own memory buffer. The 4014 was the best graphic output device of its day, at a (monochrome, one-bit) resolution comparable to today's TVs.
The storage-tube CRTs were the parent of those graphics monsters of the 1970s.
Other CRT memory (machine-readable, not visual) was available, up to a few megabytes per tube, before semiconductor memory filled that need.
CRT storage goes way back, used for RAM. A big improvement on mercury delay lines AIUI.
NT
I remember hearing an anecdote about the original MIT "stored program" computer system, which used storage-tube memory of this sort. The tubes suffered from age-related problems - I guess the phosphor layer which acted as the active storage plane tended to "burn" with time, as phosphors do.
The maintenance engineers had program decks that they could read into the computer which would perform pattern tests on the memory, and (I'm told) in those tubes, you could look at them and see which bits or regions were aging - the illuminated bit positions would be dimmer, as the phosphor aged.
One of the grad students decided to be funny, wrote up a new test program, punched it out in binary code form, and substituted it for the maintenance engineer's normal test deck.
During the next maintenance period, the engineers booted the test program... and it immediately froze. They reset, booted it again, and it froze again.
They opened up the machine cabinet to start diagnosing the problem... and there, glaring out at them from the array of memory tubes, was an unprintable four-letter word.
A stern memo was circulated through the department not long thereafter, admonishing the faculty and students that the maintenance program decks were _not_ to be tampered with.
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