Breaking News
Blog

Assessing scope accuracy

NO RATINGS
View Comments: Threaded | Newest First | Oldest First
Bert22306
User Rank
Author
re: Assessing scope accuracy
Bert22306   2/20/2012 9:01:23 PM
NO RATINGS
That's kind of an age-old question. It's not JUST about accuracy. It's also about whether you change the measurement appreciably by just touching probes to the circuit. IMO, every EE who's actually an EE has had this drilled into him throughout school and career, and has been bitten when he ignored the issue. Sometimes the absolute number isn't all that important, but what always matters is whether the scope, voltmeter, ammeter, whatever, is making the measurements irrelevant. Sort of a macro version of Heisenberg's uncertainty principle.

sharps_eng
User Rank
Author
re: Assessing scope accuracy
sharps_eng   2/20/2012 9:57:12 PM
NO RATINGS
You have to be careful when doing differential measurements (x-y) with the iNVERT function, there is no standard for where the summing takes place. Many (all?) cheap LCD scopes just subtract the pixels, so although what you see is what you get, if one of the signals clips the screen edge the diff signal is meaningless. Decent analog scopes (and some were quite cheap also) used to let you have seriously high gains which would overload each channel on their own, but when summed, cancelled the inputs so that you could get a good high-resolution view of a small signal which was superimposed on a large one (like a 100mVp-p crosstalk transient on a 24V DC supply). Its worth checking this on any scope purchase. Of course, you will eventually build a decent diff pre-amp yourself, but until then, a good ADD-plus-INVERT on your scope is very handy.

More Blogs
Incumbent suppliers of power-management ICs have an opportunity to greatly improve efficiency and integration, or lose market to rising stars.
More details about how startup Sarda Technologies heterogeneously integrated power stage module combines CMOS power drivers with GaAs output transistors in the same QFN package.
Solar Impulse II left Mountain View on its next leg of around-the-world journey.
The VENUE Act aims to curb the flow of patent infringement cases to a remote East Texas court, but itís unclear if it has enough support to pass.
Its lack of expertise in SoCs, insistence on its x86 architecture and some bad luck kept Intel from enjoying the smartphone boom.

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
Like Us on Facebook
EE Times on Twitter
EE Times Twitter Feed