Products > Test Equipment
Best Brand Name for an Oscilloscope?
nctnico:
--- Quote from: BillyO on November 30, 2022, 09:05:07 pm ---
--- Quote from: tautech on November 30, 2022, 08:25:25 pm ---Are you making these Billy ?
--- End quote ---
I may, once I have them where I want them and there is enough demand for them. Otherwise I can just make the files available.
--- End quote ---
Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't. The only proper way to measure the bandwidth of an oscilloscope is to sweep the input using a levelled RF generator.
BillyO:
--- Quote from: nctnico on November 30, 2022, 10:56:43 pm ---Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't. The only proper way to measure the bandwidth of an oscilloscope is to sweep the input using a levelled RF generator.
--- End quote ---
I wouldn't say nothing. Neither would Tektronix. Neither would physics. It's not absolutely accurate, but it will let you find out if your FNIRSI is more like 30MHz than 100MHz or your SDS1104X-E is more like 120MHz than 100MHz.
Of course the proper way is to sweep the frequencies, but not everyone can afford a 500MHz AWG to check out their 200MHz scope. However, they could probably swing $5 or $10 for a handful of readily available components and a PCB.
A small few of the folks around here ( ::) ) are not fixing heart-lung machines or calibrating self-guided nuclear missiles. They just want to have a little fun with electronics and their lab kit. Knowing the BW or their $600 scope to +/- 10% might be enough.
All that said, please rest assured I'll check myself before I wreck myself and not get too wound up. :-+
nctnico:
Well, you can buy a simple function generator to check the bandwidth of an oscilloscope. Like one from Uni-t or Feeltech. That is a lot more useful compared to wasting money on a device that just outputs a square wave. And likely the 1kHz calibrator output of the oscilloscope already has steep enough edges.
bdunham7:
--- Quote from: nctnico on November 30, 2022, 10:56:43 pm ---Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't.
--- End quote ---
"Nothing" is a bit overstated--risetime gets you in the ballpark for bandwidth and whether the factor is 0.35 or 0.45 is a detail. And I'd say that in a lot of cases, perhaps most, where the factor does significantly diverge from 0.35, the user may actually be more concerned about rise time than actual bandwidth.
BillyO:
--- Quote from: nctnico on December 01, 2022, 12:25:42 am ---Well, you can buy a simple function generator to check the bandwidth of an oscilloscope. Like one from Uni-t or Feeltech. That is a lot more useful compared to wasting money on a device that just outputs a square wave. And likely the 1kHz calibrator output of the oscilloscope already has steep enough edges.
--- End quote ---
A cheap 30MHz FG is not going to tell you much about the BW of your 200MHz scope unless it has a rise time of less than 2ns. They don't. No probe compensation calibrator I know of does either.
The fact is the transient response of a system is directly related to it's bandwidth and with careful measurements you can get a very close determination of that bandwidth.
Here are some articles on it. If these don't give you enough information, there dozens.
https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=9817
https://www.signalintegrityjournal.com/blogs/12-fundamentals/post/853-back-to-basics-bandwidth-and-rise-time
https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Operational_Amplifiers%3A_Theory_and_Practice_(Roberge)/03%3A_Linear_System_Response/3.05%3A_RELATIONSHIPS_BETWEEN_TRANSIENT_RESPONSE_AND_FREQUENCY_RESPONSE
Besides, a high slew rate pulse generator has many other uses.
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