My recent Tek, Agilent, and LeCroy oscilloscope fun

Oh. Never mind.

John

Digital or analog? A couple of years ago my employer bought an Atten AT6011 (1GHz + tracking generator) for simple RF stuff and EMC problem finding. It takes some time to get used to an analog instrument but it does work.

Isn't that just how the market works? If there are more competitors prices will drop.

No. When a big company drops their prices below their own cost, to keep a small company from entering a market, that's not sporting, and it's usually illegal. The guys at Los Alamos were deliberately trying to nurture a new source, to compete with the existing one, and LeCroy used their economic power to kill off the attempt. Luckily, they were too blatant about it and didn't get away with it. The customer knew that, if they accepted the half-price bid, we wouldn't be a competitor in the future, and they'd be stuck with a single high-price, low-quality source. So, intelligently, they rejected the lowball bid.

When you sell something below your cost, to kill another source, than's not competition, it's against antitrust law.

John

How's the waveform update rate on those things?

I bought a Tek TDS3014 about 7 years ago for home hobby use. That cost me 2.5 years of my allowance. I don't regret it. At that time, the TDS3000 series was where the price/performance breakthrough was.

I'm considering to get an Agilent DSO7034 350MHz in a few years, then upgrade some time to the digital channels option. People spend a heck of a lot more on Harleys and other useless toys.

I'd like to build a Q-switched YAG laser or N2 laser and do a time of flight speed of light experiment for my daughter when she gets to a grade where that will make sense. Maybe 3rd grade or so ;-) Might even be able to get LEDs to do the job. I could probably measure it with my

Don't recall. Seems fine for 98% of general lab work.

Easier, and more dramatic, might be a spark gap. I think the first cloud bounce work was done with spark gaps and PMTs.

A spark gap can produce a not-many-ns high-power light blip, small enough to focus pretty well, parabola or big honking fresnel lens maybe. That might appeal to a kid. Hey, make your own capacitor!

John

We did that in, Physics 2 or something, using a regular laser diode, a rather slow photodiode, and the hallway. The mirror is moved to set distance. Fifty feet or so makes it easy. The hardest part is aligning the mirrors, and foot traffic making them bounce.

Tim

in:

Below your _marginal_ cost, no?

Cheers

Phil Hobbs

Yeah, we did the same thing, but with an N2 pumped dye laser and a

Trying it with a retro-reflector might be interesting.

That's not a bad idea. Of course, a laser-induced air ionization spark would be fun too!

Some folks are using laser sparks for broadband fast optical sources.

But I am having fun these days employing power LEDs to displace some Xe arc lamps for Schlieren imaging light sources.

My Rigol (Agilent-branded one) updates about as fast as the lcd can display, but then it only have 4k memory.

I just tested how small time difference my 100 Mhz Rigol can detect: about 0.5ns. If I feed both channels same signal they differ about 0.2ns

But my pulse generator is manual one ie. striking wires into solderless breadboard damn fast, and that generates bit ugly signals. Would be interesting to know what the risetime of those pulses is. I am pretty sure it is under 1 ns but how much, that I don't know. Anyone with a real scope wanting to experiment?

-ek

Actually there is no use to update the screen very fast. The human eye can't deal with that. What most scopes with an LCD screen do is combine many sweeps into one image and thereby simulating the good old CRT scope. The oldest sweep has the least influence (displayed using faint dots).

Waveform update rate on oscilloscopes is not the same as display update rate. The latter is not particularly relevant. Waveform update rate is essentially acquisition rate, not the sample rate, but the rate at which triggers may be responded to and result in acquisition records which map to the display.

Some scope architescures, such as Agilent 6000 and 7000 series, can update 100000 waveforms/s. This can be done even if the time to fill the acquisition memory is greater than 10us. For instance, at 4Gs/s, it takes 1 ms to fill 4MB of acquisition memory. But on a 1us/div horizontal scale, the screen represents only 10us of time. The scope can on a setting like this achieve about 50000 wfms/s.

The importance of this is that if you have an intermittent anomaly, such as a glitch or runt in a signal that occurs at 1ppm on a very fast signal such as a memory bus transacting at a MHz, for ex., then if your waveform update rate is only 10wfms/s, you have only a 1/100000 chance of finding it in one second. Ie, it will take 100000 seconds to ensure

However, with a scope that can capture 100000 wfms/s, it will only take

This is one of the things worth paying up for with higher-end scopes.

Interesting, I would have expected much slower response with just a probe and long ground wire. But I can get 3.5ns rise time plugging my probe into a 5V breadboard rail, on a 100MHz TDS3014. Since the rise time of a 100MHz system is 3.5ns, this suggests that the actual input at the probe tip is relatively impulsive (ie, much faster even) compared to the scope front end.

I will try this at work with a 500MHz scope. In a few more weeks, I can try it with the 1GHz scope.

This is clearly convincing me that I may need to go to a full 1Ghz scope for my hobby electronic projects ;-)

i-A series oscilloscopes.

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The new Tek 5000s and the new 4000Bs have new Low-C passive probes standard which you likely won't be seeing on any other scopes, plus the Tek 5000s runs Windows rather than the embedded OS.. I wonder if you'd like Tek much better if you had reviewed one of those 5000s... The 5000 also can do >250,000 acqs/sec like it's big brother the

-Jeff

Wouldn't the 1.5GHz Agilent 1163A probe count as a "low-c passive probe?"

pF and

No way! That probe loads your circut down with 500 ohms! For general purpose debug that would be terrible! I don't want an extra couple milliamps going to ground through the probe when I probe various circuits. I guess if the highest resistor you have in all your circuits is 100 ohms, then you could get your job done with this probe.. This probe is intended for probing 50 ohm envionrments.. The new probes from Tek are 10 Meg ohm 10X passive probes with up to 1Ghz of bandwidth.. Nobody else offers that..

Got a part number?

I was thinking you meant something like the Tek P6158, which is 1k input resistance.

Thanks,

---Joel

The part numbers are the TPP0500 and the TPP1000. They basically are the follow-on to the P6139A or P6139B but with half the probe C (