A few weeks ago I asked the Hackaday community for some. Thank you very much to those of you who responded both here online and in person among my friends closer to home. I followed the overwhelming trend in the advice I received, and bought myself a Rigol DS1054z, an instrument with which I am very happy. It’s a nominally a 50 MHz scope, but there’s a software hack that can bring it up to 100 MHz. How fast can it go? My trusty Cossor, its 2 MHz bandwidth as yet unverified.

I am looking for a new oscilloscope and I am considering an Owon sds7102. However, with a little extra effort and a USB connection you can download a much. Your computer using free software such as the Python Scientific package. You cant go wrong with the hack, you will have a first class scope.

This question became a mini scope-shootout after a conversation with my Hackaday colleague [Elliot] about measuring oscilloscope bandwidth, and then my fellow members producing more than one scope for comparison. You know who you are, thank you. I found myself with ready access to several roughly equivalent models and one very high-end one in specification terms representing different strata of test equipment manufacture, and with the means to examine their performance.

I thus had a chance to look at what the extra money secures in performance terms when you buy an instrument, and gain some idea of whether a more impressive badge is worth the outlay. So what follows is not quite a review of oscilloscopes because I’m not going to dive into feature comparisons, but an evaluation of the bandwidth performance of scopes from several different manufacturers.

Bandwidth vs Everything Else You might think that what matters in a scope is its timebase; that its quickest setting will tell you how high a frequency it can display. And in a sense you’d be right, but if the scope’s internal electronics are only able to resolve a signal at 50 MHz, it doesn’t matter that the screen can trace out faster signals than that — it will just smear the same 50 MHz signal across more squares of its graticule. If you’re looking for wiggles at a higher frequency than that, they just won’t show up. A scope’s _bandwidth_, the highest frequency wiggles that it can resolve, is what we care about with respect to “speed”. How does one measure the real bandwidth of an oscilloscope then?

The simplest way is to give it a voltage transition so fast as to far exceed its capabilities, and measure the extent to which it has trouble catching up. If you feed it a rise time measured in picoseconds and count the nanoseconds of the rise time that it reports, there is a handy formula to derive the 3 dB bandwidth of its electronics from that figure. Bandwidth (Hz) = 0.35 / measured rise time (S) In practice it’s convenient to remember that for a rise time in ns the formula returns a bandwidth in GHz. The Hackaday avalanche pulse generator. Analiticheskaya himiya uchebnik dlya farmacevtov. The fast rise times used for the tests in this article come from following a design from, producing roughly 500ps rise time pulses.

It uses the ubiquitous 2N3904 general-purpose NPN transistor, and since it requires well over 100V for the transistor to enter avalanche mode it incorporates a small switching inverter using parts scavenged from a scrap ATX power supply. The whole device is built dead-bug-style on the back of a surplus PCB from a prototype run, and connects to the scope with the shortest possible BNC lead. In this realm of measurement the slightest stray capacitance can cause a significant lengthening of the measured rise time.