A good digital oscilloscope?

Shouldn't be wearing a dress? :)

P7 phosphors were very common on all sorts of air search radar (PPI -=20 plan position indicator) displays post WW2. I have seen them on SPS-48=20 and SPS-51 native radar displays.

nearly=20

fancy=20

get

Roger on the beta decay driving the luminescence. But not on the = centuries=20 life, the half life of Radium 228 is only 5.7 years.

Williams"

or=20

photoflash=20

that:

=20

The last time i saw a synchronizer type 'scope was over 40 years ago, it=20 was a neighbors prize possession and 10+ years old even then.

Well, it says "TRIG LEVEL" on the outer knob, but it has this peculiar "STABILITY" on the inner knob.

I never did completely understand the circuit in this thing (I have the kit instructions, so I have all the drawings), it's drawn so as to make a minimum of sense.

Tim

They work similar to an injection oscillator where mildly force-feeding it some signal makes it synchronize to that signal. More or less, depending on how strong you tie them together. Problem with synchronizer scopes is that the user really has to watch it. Crank up the stabilizer knob too much will make it appear rock stable but will distorte the signal that's being shown. IOW, what you see is not necessarily what you get. The X-axis (time) becomes non-linear.

not at=20

=20

least 18=20

uncommon on=20

birthday!

bunch of=20

debt=20

I've=20

=20

Look him up and have a nice dinner with him about that time (provided 'e = is=20 still around). (Or on some chance her).

On a sunny day (Sun, 13 Dec 2009 09:02:40 -0800) it happened Joerg wrote in :

Then the design is wrong. Consider this circuit: -------------- + | | |--- [ ] R2 -->| Q1 | | |--- | | | |-------------------- | [ ] R1 | | -------| |---- [ ] R3 |----\| Q2 UJT | | |---- \| Q3 | | |---===---< Sync pulse === [ ] R3

info_at_cabling-design_dot snipped-for-privacy@foo.com

and,

some

with.=20

which

flat(er)

learn?

these

Since DA took a pass i must ask, does it include probes? Option 1M?

to

never

=20

the

have

look

even

Instek, Rigol, and Hameg are ODM for Agilent, Tek, and Phillips(?); not=20 necessarily in that order.

Wiki claims 1% loss in 25 years, I presume from natural radium.

John

He'd be around 110 years old ;-) ...Jim Thompson

On a sunny day (Sun, 13 Dec 2009 17:46:14 GMT) it happened Jan Panteltje wrote in :

OK, forget it, this is not an injection osc.

I don't think it's nonlinear- the actual ramp generated (I don't have a picture) looks okay. The deflection amp has terrible bandwidth (maybe 1MHz if that?), so the top range (0.1us/div) looks like s*it,

I've probably seen the distortion you suggest, but I'd call it stray coupling, not distortion:

What I really meant by "never quite understood" is, I never looked deeply at the circuit's specific design. It's kinda sorta triggered: I know it has a diff pair input (the +/- trigger polarity switch connects to the pair's collectors), exactly one 74xx logic chip (dual 4-input NAND, I forget what number), and some things that one would expect to see in a triggered sweep generator, like the variable current source and timing caps and discharge transistor (a house marked 2N2369, so they cared about switching speed). It's what's inbetween that I haven't untangled, and I have to wonder if the circuit was drawn so convoluted just to defeat such attempts...

Tim

Older triggered-sweep scopes, like the Tek 545, had a "stability" knob. It usually set the threshold of the Schmitt trigger that followed the trigger discriminator. At high trigger frequencies, one would tweak it for a stable display. Turning the stability knob one way would free-run the timebase (before "auto" was invented), the other way would kill it.

Later scopes, with faster (tunnel diode and such) trigger logic, didn't need this.

John

Ewwww! An UJT!

It's a bad scope, okay, but not THAT bad! ;-)

No, that's a bad way to control stability, you'd want to control dead time or discharge time (the latter isn't possible with an UJT). As shown, you're changing dV/dt, which needs to be in calibrated ranges.

Tim

Yup, I played with one of those in lab once (school lab, for doing real school lab work). The Rigols they hand out suck at X-Y plotting, so I rolled that behemoth on over, plugged it in and away I went.

The first thing I noticed is the knobs are all in terrible positions. I guess they didn't have the luxury of putting things in nice places, since everything is stacked up inside, tubes and terminal strips and all. Not like the 475, where there still isn't a lot of free space, but it's all on PCBs, positioned where it needs to be.

The second thing I noticed is, the "delayed/B sweep" -- which sounds to me like the delayed sweep on the 465 -- I couldn't get to work, at least as I thought it should.

Lastly, the manual (which was convieniently sitting on the cart) includes complete schematics. What madness drove them to hybrid tube/SS circuits, who knows! ;-)

Tim

On a sunny day (Sun, 13 Dec 2009 13:12:54 -0600) it happened "Tim Williams" wrote in :

'Vernier' is the time base speed, or in this case frequency. Actually that circuit needs a comparator so it can only trigger when the sweep is past the most right point. UJTs are cool. Unlike tubes, that get hot. Only synced scopes I have seen were old and had tubes...

The 545-547 scope front panels were wonderful. You could grab a fist full of knob, with serious detents, and wail away. They were a pleasure to drive.

Kids these days.

John