Digital CRO Angst - DC Level

"Paul Norman"

** That is like "graduating" from Heaven down to Hell. ** That is not what normally happens.

Your scope may have a fault.

Despite its many failings, my Rigol knows where the zero line is.

... Phil

On a sunny day (Thu, 22 Dec 2011 08:35:05 GMT) it happened snipped-for-privacy@kendricks.com (Paul Norman) wrote in :

Whatever you do, also hang on to your old CRT analog scope. I got bitten again recently looking for some noise, while one look with my analog scope revealed a RF carrier interfering. On SOME settings of the digital you could see interference...

Digitals are nice to look at stored waveforms, and one time events, but maybe for the rest they may have been imposed on you by the need to sell ever new equipment, that often is worse than the ones it replaces in many aspects, like digital TV is with compression systems like MPEG replacing analog. And, why do not have these new scopes a video player? All the required hardware is there :-)

"Graduate"??? For low-noise analog design, using a digital scope is like trying to fold origami with your elbows. Digital scopes have their place for slow and one-shot events, but for general troubleshooting they aren't the best choice. Hold on to that Tek analog scope!

Which didn't have any of those readouts!

Frankly, when you buy the cheapest possible instrument, you can expect it to behave that way.

The Rigols are good. My 1052E works great. It's my default bench scope, and I have about 50 oscilloscopes of all sorts. My other favorite is our Tek TPS2024, with all four channels and the trigger input fully isolated.

John

I've used a couple HP scopes (54600 series) that aren't bad. The software actually works, unlike any new Tek, where you have to wade through menus that take seconds to load (no kidding, it can take seconds to chug the kpoints on the scope display before it gets around to displaying any new information). The older ones, like the 54600 itself, are simple, point and click (well, point and press), not very impressive (100MHz bandwidth, equivalent time sampling below, get this, 20us/div, which I think puts it around only 20MSa/s!). The 54622 is newer and has some neat improvements (digital phosphor to some extent, more math, more samples). The newest scopes, of course, have color screens and all that, but the soft key icons are all per-pixel identical, give or take a little antialiasing or gradient to spruce them up.

Analog scopes - old Tek. Digital scopes, HP/Agilent, or maybe Lecroy and others, depending on how much you want to spend? Bottom basement, Rigol (it's as slow as a Tek, but you don't get your hopes up because it's not brand name!).

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms

Thats absolute nonsense. Its just a matter of getting a decent DSO. There is a huge difference in trigger (sensitivity) and how signals are displayed.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico@nctdevpuntnl (punt=.)
--------------------------------------------------------------

"Nico Coesel"

** Fraid it is an absolute fact.

** Right - one that performs just like an analog one.

Those are very expensive ....

** Completely off with the fairies ....

.... Phil

ever new equipment,

Amen to that!

--
"For a successful technology, reality must take precedence 
over public relations, for nature cannot be fooled."
                                       (Richard Feynman)

Ahem ... I do believe HP was selling rebadged Rigols, at least at one stage.

From what I gather, Atten is more or less last generation Rigol.

Paul