A huge component my New Year’s Resolution to improve my total style process was much better screening. Much better testing is an integral part of better as well as a lot more deliberate layout, yet it suggests having devices that you can rely on which can consistently provide you the outcomes you need.
While I’ve accumulated a respectable little collection of toys throughout the years, I spent a fair bit of time late 2011 figuring out exactly what I wished to include or change on my workbench in 2012 to be able to boost jobs I’m working on. On top of the list was a quicker mixed-signal oscilloscope, followed by a much more dependable bench-top multi-meter, and a decent function generator rounding the large ticket products out.
After spending quite a bit of time selecting a range that matched my spending plan and also demands, and also looking (importantly!) at the ecosystem around that scope, I settled on Agilent’s new MSOX2000/3000 collection– particularly, the Adafruit Xmas Elves chose an MSOX2024a (the screenshot above was handled this scope). These ranges (in my point of view) are an outstanding value for a mid-range scope, and also truly raise bench for the competitors in the $2-5K range. I would love to create a couple of article on the factor behind that choice and the assuming behind the whole list of items over, yet as an initial foray into that I believed I would certainly aim to describe some of the specifics you should bear in mind if you’re thinking of an extent on your own (probably the most beneficial tool on any EEs workbench after a multimeter).
One of the most apparent element when selecting an oscilliscope is data transfer. 50MHz is far better than 20MHz, and also 100MHz is definitely much better than 50MHz, and so on, but just what does that number really indicate, as well as how fast is quick sufficient for your needs? There are currently some excellent sources available that go into exhaustive details on this … but also for the exec recap kept reading.
The biggest influence on the price of a scope is it’s data transfer (50MHz, 100MHz, 200MHz, 350MHz, … 2GHz, etc.) and the number of analog examples per secondly that it can check out (1Gs/s, etc.). These 2 numbers are related, as well as most people know that the examples each second have to go to least 3-5 above the data transfer for exact results (suggesting a 100MHz range must have ~ 500Ms/s, or even far better 1GS/s for trustworthy results).
Yet just what does the 50MHz or 100MHz truly imply? If I purchase a 50MHz scope can I precisely catch and measure 50MHz well worth of information? The answer (like everything else in engineering) is: it depends. You should be able to gauge regularity as much as or even past the maximum rated value, so if figuring out regularity is all that issues (inspecting exactly how precise the outcome of an oscillator is, the pixel clock on an LCD controller, etc.) you can securely increase to the maximum. Where things come to be more blurry is amplitude (the top and also lower voltage worths measured by the scope).
The bandwidth of an oscilloscope actually shows the factor at which the gauged amplitude on an amplitude/frequency graph has actually decreased by -3 dB (or 70.7 %) of the initial worth! Your frequency will excel approximately and possibly even slightly beyond the optimum rating of the range, however at the maximum rated frequency, the amplitude will be ~ 70 % the actual value so you’re 5V signal will really appear as ~ 3.5 V, and 3.3 V will certainly appear as ~ 2.3 V! This could create you to panic as well as assume you have a bad oscilloscope, or that your PCB or circuit is rubbish, simply because you could not have actually been aware of this concept.
As an instance, have at consider the screenshots here. They’re both catching the 3.3 V 40MHz pixel clock of a big (800 × 480) TFT LCD, and also the frequency coincides, but the optimal to peak voltage on them is really various. The Tektronix image is from a 350MHz oscilloscope (using a 500MHz probe because this is likewise important!), and also the other is from a 50MHz Rigol extent (sw ‘upgraded’ to 100MHz) making use of the probes in 1x method (which is limited to 7MHz bandwidth). The optimal to come to a head voltage (VPP) on the Tektronix scope is accurate (it says 3.4 V considering that there is a slight top on the rising side), yet the Rigol only reveals 1.4 V, though both capture the 40MHz regularity appropriately!