[Diy_efi] Choice of labscope

Marcello A. Belloli mbelloli at speedymotorsports.com
Sat Feb 26 16:02:58 GMT 2005


Hello Will,

> Hi Marcello,
>
> The problem with a storage scope is finding ways of triggering the thing
> so
> it shows what you are looking for.  The proposed new scope should be up to
> the job, as the minimum timebase sweep duration gives 50 nsec per division
> it
> seems.  This should show events down to 10 nsec, bearing in mind the
> bandwidth
> limitation.

     Now when you are  talking bandwidth, you are talking the 100mhz, or
are you talking the samples per second?  I've trying to understand
this difference.  Now if I'm reading this right....the samples per
second is the rate at which you can get a freeze frame (digital
storage)?  Like the signal you see for but a moment, and want to try
and capture because looking in real time it goes by too fast.  But a
repetitive signal you can just basically look at 100mhz, because
there is no need to capture it.  It is always in front of you.  So
the bigger the storage buffer, and the faster the storage rate will
give you the better chance of glich capture.

>
> Getting it to look for the event you wish to capture **at the time it is
> happening** is the real challenge!  When I was working as an engineer, we
> would
> sometimes write code routines to do a certain step repetitively to catch
> those events, but this is a much more practical proposition if you have an
> E(E)PROM emulator, a very desirable tool.  Much cheaper than a logic
> analyser too.

     Now when you say e(e)prom emulator you are talking about a device
that would plug in place of an eeprom emulating it.  Now I have a
romulator, which does that exact thing.  The funny thing was it
wouldn't work on my last project.  I could set it to emulate a 2716,
which is the exact chip I used in the end.  But it wouldn't work in
the circuit.  Probably because I was modifying the input to emulate
another chip.  It worked as a 27c256 no problem in the past though. 
I'm guessing what you are talking about must do more than what I
have.
     Now if I could get a logic analyzer at a good price would that be
better.  I see an Hp DSO / logic analyzer for sale on ebay that
struck my interest.  It has both in one unit.  Just not sure yet if I
can capture the data to my pc.  The tektronix ones I've been looking
at work with software I already own for doing captures.

Thanks,

Marcello
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