[sdiy] Pocket oscilloscope

[Byron G. Jacquot]

>You get what you pay for though.  It's likely that cheap Chinese scopes like 
>Digimess, Rigol, Tenma, etc, still might not use these tricks, or might cut 
>corners to keep down the memory requirements / cost.

I can concur with Richie.

The good digital scopes made today are pretty darn usable.  The companies that make them have an interest in giving the user the most legible, meaningful output.  If you have to apply extra, expert, interpretation to the visual results ("oh, that's just ringing of the decimation filter...my square waves actually are sharp-cornered"), they're a lot less useful a tool.

I've got a newish Tek TDS2024 that I'm very happy with.  The triggering is rock solid, and I spend a lot less time questioning whether the funny results I'm getting are because my circuits are broken, or my scope is misbehaving.  Tek also have some pretty good direct deals on refurb scopes.

I've also used the cheap imports under the Rigol and Atten names.  On the surface, they feel a lot like the Tek TDS - similar menus, colors and buttons and stuff, but in actual use, their behavior seemed flaky.  Switching timebases one one caused funny behavior (like it would just stop sampling, and you've have to hit "run" after every click), triggering was touchier, getting them to do a one-shot capture took a lot more effort.

A colleague of mine had a DSO-quad that we played with.  It was OK for some things.  I was unable to figure out how to show a small waveform that was riding a significant DC offset.  It wouldn't let me move the ground reference mark for the channel off the bottom of the screen.  I'm guessing it was running the stock firmware - maybe the community firmware solves that?

-Byron Jacquot