22 Aug
2005
22 Aug
'05
2:53 p.m.
[ELektor GBDSO]
My thoughts exactly. I don't usually build stuff
when the firmware sources
are unavailable. It also seems to be quite limited - high AF at best, not
much good for anything other than debugging audio gear.
Actually, a low-bandwidth scope is still useful for looking for power
supply ripple, looking at motor drive signals, SMPSU waveforms, etc. This
one, like the Velleman LCD 'scope that I have, has the advantage that
it's not connected to the mains, so it can be 'floated' (taking great care!)
for looking at signals on the mains side of an SMPSU.
[...]
I'm also toying with the idea of building a 40MHz
version of the GBDSO. The
hard bit is finding amplifiers that are fast enough, and learning about the
analogue side of things - I've never really done any analogue design.
From what I rememebr, Burr-Brown did some nice ones,
Analogue Devices did
some with very misleading data sheets.
Be warned that hogh-speed analogue design is not easy. 'Strays' (PCB
inductance nad capacitance) matter even more than for high speed digital
design. Op-amps misbehave, it's not at all uncommon for there to be
significant phase shift at high frequencies -- enough to turn -ve
freedback into +ve. If you're trying to get a low gain out of an op-amp
-- that is, you've applied a lot of -ve feedback -- it's likely the darn
thing will turn into a nice RF oscillator.
-tony