[Noisebridge-discuss] cheap USB Analyzer, or signal integrity tools?

[John E]

I'm not a EE either, but i've been working with electronics since I was a
young child.
It depends on the voltage range. From what I recall, most expensive logic
analyzers will support input swings below 1v.
As long as the swing voltage is above around 2v, then there are ways to
protect it with signal diodes or FETs, so the problem isn't insanely
difficult.

Also, USB buses have more powerful drive circuitry, compared to say the
input pins of recent CPU, so the input stage wouldn't have to be as
sensitive.

John

On Mon, Nov 8, 2010 at 1:22 PM, Andy Isaacson <adi at hexapodia.org> wrote:

> On Mon, Nov 08, 2010 at 01:17:03PM -0800, John E wrote:
> > Are you talking about during assembly or during use?
> > A couple of diodes in the input stage to protect against being blown up
> by
> > static or wrong voltages,
>
> I'm not an EE, but it's my impression that building a decent input stage
> for a 0.5 - 1.0 GHz signal is nontrivial, especially if you want it to
> be able to withstand 12V shocks (for when your hobbyist user
> accidentally touches the probe to the power rail while attaching the
> debugging tool).
>
> Certainly the last time I worked in a lab where others had such
> equipment, they were very careful around the logic probes and protocol
> analyzers (to a degree they weren't around the multi-GHz LeCroix scopes,
> they even let software douchebags like myself use them).
>
> > would solve any fragility concerns during use.
> >
> > The DSO Nano doesn't appear to have any real input protection.
> > http://bbs.e-design.com.cn/bbs/UploadFile/2009-10/20091023176982804.jpg
>
> Like every oscope in my experience, it has auto ranging, and in my
> experience is OK with getting 12V even if it's set to mV range.
>
> -andy
>
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