Scope intensity markers, why not

You mean that it brightens the trace if it hits that risetime, or you get a dot on the x axis?

The MIL Stds require that all this field technical equipment and accompanying documentation be accessible to anyone with an 8th grade level of education. But even that might be unrealistic.

He has to mean it puts a z-axis tick on the beam at the specified intervals. The user is then relegated to counting ticks, and if they're especially clever, they might even try inter-poh-lation to refine the reading. Geez.

On the digital scopes, you press "measure" then "rise", and it computes and displays it for you. Digital scope is to analog scope as calculator is to slide rule.

John

Avoiding creeping featuritis? I mean, I like a panel full of knobs and switches better than most, but the feature has marginal utility IF you trust your horizontal sweep.

I suspect the Waterman has it as a result of a real or imagined distrust of horizontal sweep scale or linearity. For typical instruments of that day, I don't blame them. The scales were more of a suggestion than actual calibration if it wasn't a Tek or HP :-).

I think some Tek scope calibrators of the 50's/60's would have a Z-axis output that showed pips for use in scope alignment.

Tim.

"Ancient_Hacker" wrote in news: snipped-for-privacy@e56g2000cwe.googlegroups.com:

How did you determine the 10% and 90% points on the test signal? TEK's graticules were designed for easy risetime measurements.

Tek had an option for their 7704A that was an xtal-controlled time-mark generator,but it wasn't very popular.

You could input your timemarks on channel 2,that's how we did some calibrations for other instruments.

--
Jim Yanik
jyanik
at
kua.net

I gues I'm somewhat confused as to how Waterman implemented that in

195?

Seems like the z- axis ticks would need to be synchronized with the start of the horizontal sweep so the ticks wouldn't "crawl." I suppose they could have used a triggered multivibrator, but I can't imagine a technique like that being usably accurate without a lot of complication. Sounds like an awful lot of tubes to make it really work. Actually, I've never seen a Waterman scope with triggered sweep, come to think of it.

I don't have the manual anymore but IIRC it didnt take much circuitry. Your basic R-C blocking oscillator is more than happy to sync up to anything. That only requires one tube.

It was probably a way of measuring time durations on a scope with uncalibrated and not terribly linear sweep.

I had a USN24C back in the early 70's and was sorry to lose it to a shorted power transformer after only a few years of use. It was the best I could afford back then. Cheers, Hank

IIRC, one of the modes of my Tektronix 545 scope uses a z-axis marker to measure time. The 'tick' position is adjusted with a 10 turn pot. setting multiplied by the B time base setting. Its not the same as what JF described, but it does use an intensity marker.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
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Bureaucrat, n.: A person who cuts red tape sideways. -- J. McCabe

A_H wrote: It was probably a way of measuring time durations on a scope with uncalibrated and not terribly linear sweep.

And of course, therein lies the reason others didn't bother. Especially with graticule etched on the inside of the glass, it's as easy to count division as brightness tics. Some later scopes also came with very accurate time measurement capability, and with features like delayed sweep that would let you superimpose two sections of the trace and read out the delay time directly.

Cheers, Tom

Speaking of fancy old-school oscilloscope features... the old Tek analog scopes (e.g., 2465) that actually had *on-screen text read-out* of measurements such as time, frequency, etc... weren't those things designed back in the '70s and early '80s? And as such didn't they probably need some paper sheet-sized board full of tons of digital logic DIP ICs, PROMs, some CPU, etc. to pull off such a task? And did they add a dedicated electron gun for writing the text, or just update it inbetween sweeps? Mighty impressive...

We've got an HP 8594 spectrum analyzer kicking around the office that weighs a ton but has built-in BASIC and will let an externally GPIB-connected peripheral (e.g., a PC) draw directly on the screen using a subset of HPGL commands; also rather impressive given its vintage.

---Joel Kolstad

On forgotten scope features:

Some time ago, I had a "hobby - grade" scope in the office fitted with an Y output. Very convenient, one could connect e.g. a counter, and use the scope as a pre-amp. I usually connected a simple amp with a speaker. It is amazing what an "audio track" can reveal when doing measurements in a prototype.

When measuring datalines on a processor board, you could actually

*hear* the software processes going by, and hear the system hang after a visible & audible glitch somewhere.

Also great in repairing audio systems - seeing and hearing a measurement was extremely revealing. Incoherent waveforms might sound very familiar.

My fancy Lecroy does not have this feature - I still miss it...progress I guess.

--
 - René

Actually by the time of the 2465 (which I personally regard as a "new" scope) good chunks of the functionality were handled by microprocessors. Yeah, there are PROM's and a CPU and NVRAM etc. More notably there are a couple of custom Tek chips.

What I think is impressive are the early-70's-vintage Tek plug-in mainframes where there was no CPU but they did have on-screen readout. There's a "bus" of sorts in the mainframe that modules can use to communicate (via mostly analog levels and time-based multiplexing) results (not just numeric values but very importantly scale) to the character generator (made of a mix of standard analog+logic and custom Tektronix analog-digital stuff) that puts them on-screen. These have two distinct modes, one where the character writing interrupts normal operation of the scope, and another where the character writing occurs in the refractory period between sweeps.

The character generation/selection logic is filled with substantial amounts of cleverness (a lot of it embedded in the Tek chips but the time-division bus is really very clever in terms of compactness and implementability) so that it does not fill sheet-sized PC boards but is in fact rather compact.

For the ultimate in character-generation cleverness, witness the Tek

4010 and 4014 serial terminals, which use storage scope technology every way you could ever imagine. They pioneered affordable computer graphics terminals way before anyone else (there were some stratospherically priced ones from other outfits). One gotcha: the RC-controlled baud rate generator!

Tim.

I think on later Tek scopes this mode was more generally called "A Intensified by B".

I personally was usually confused by all the different modes possible on a dual-timebase scope. Yeah, I made use of most of them at some point or another, but it was never awfully intuitive (unlike most of the other functions on an analog scope, where the knob I was turning made perfect sense in relation to the change in display, to the point where my fingers knew how to get me the display I wanted. A wonderful feeling compared to hitting all the buttons on front of some of today's digital scopes.)

Regarding my confusion: The tek dual-timebase scopes I used had that funky dual-concentric timebase knob and 4 to 6 buttons for mode selection. The confusion I get in using them is minor, though, compared the confusion every time I look at the 140-button DVD remote control!

95% of the DVD remote buttons have zero on-screen effect when I press them! How am I ever supposed to figure out what they do!

Tim.

Or 'B intensified by A'.

Somewhere in Montana, the cover on a missile silo is opening and closing for no apparant reason.

--
Paul Hovnanian     mailto:Paul@Hovnanian.com
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Applying information technology is simply finding the right wrench
to pound in the correct screw.

My keyboard is very relieved that I wasn't drinking anything as I read that line ;-)

in my 7904s, the OSD board is smaller than A5. I'm far too lazy to pull a cover off and measure it though :)

Cheers Terry

pish tosh. there are numerous jobs analogue scopes are better at than digital scopes. Ballast, for example - my 7904s are excellent, but the puny TDS224 weighs less than a wendys super-combo :)

Cheers Terry