Re: Are low/lower cost USB Oscilloscope's any good?

"news.valornet.com" <nospam38925@xxxxxxxxx> wrote in message
news:8ed43$45805409$d861a4c3$27629@xxxxxxxxxxxxx
I just don't know if I could part with the money for a portable scope like a
fluke 123 however just for playing around.

I wouldn't. You're much better off getting something cheap, playing with it
for awhile, and then -- if you're motivated to go further -- getting the
high-end Fluke stuff.

1. Do most scopes have decent voltage input on them? For example, can you
hook most of them up to line power (120vac or 240vac)?

No! It depends a lot on the scope, of course, but most don't want to see more
than "some tens of volts" directly.

You can, of course, easily build yourself "high voltage" probe that are just
resistive dividers.

2. I also see a bunch of references to X10 probes. Are these used to
reduce the voltage to something a scope can use, for example 240VAC -->
24VAC ?

x10 probes are actually used more to not load down the circuit being probe
than to bring 240V->24V. This is done because heavy loading kills a circuit's
frequency response -- the idea probe would have *no* influence on what was
being measured, but a good approximation of this becomes difficult to do
(especially *inexpensively*) when you start getting into the hundred MHz and
up ballpark.

3. Do you have any recommendations for a scope that works on a notebook
that is relatively low cost that has decent features (keep in mind I have no
idea what features you would want in a scope).

I've been impressed with these guys: http://www.cleverscope.com/ -- they seem
to have a solid understanding of what terms like "noise" and "jitter" mean,
unlike many of the cheap scopes out there.

These guys: http://www.bitscope.com/ ...are popular (they're one of the
original players), but their performance seems a little lacking these days.
In their older models, you couldn't sample both channels simultaneously (well,
"chopped") without decimating the sampling rather either... uggh!

I would even consider some of these scopes that are free based ones that
work with a sound card, but my question is, what type of voltage input can
you get with a microphone jack???

I'd guess something under a voltage.

---Joel


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