[sdiy] Slightly OT, Logic Analyzers...

[patchell]

   My logic analyzer, an Arium ML4100, uses NE522 comparators in the logic pod
to do the threshold setting.  I would imagine there are better comparators
around these days (Don't even know if the NE522 is made...and oh yeah, this is
a 20 some odd old memory, so the number might be off just a bit).

The Proteus wrote:

> All,
>
>         I've been contemplating designing a very small logic analyzer with
> some Linux software to run it. One of the features I'd like to have is
> support for multiple logic types (TTL, CMOS, LVTTL, etc...). Now, from
> what I'd assume, the logic capture hardware is basically a latch being
> driven at high frequencies, and then that latch data is being stored in a
> buffer memory somewhere. That's all simple to me... the question I'm
> kicking around currently is how to get the input voltages in line with the
> latch. If you've got a 5V latch and the input is a LVTTL signal, how do
> you translate the high, low, and threshold voltages appropriately? This
> isn't a big deal for basic TTL<->LVTTL or CMOS<->TTL type circuitry, but
> when you get down to 1.8V and 1.5V Vcc rails, the appropriate level
> translator could get quite tricky to design - especially in commercial
> logic analyzers where there are 128+ channels.
>         Does anyone have any ideas on a good, low-cost level shifter I
> just described? Yes, my goals are lofty to top out at commercial analyzer
> channel counts, but hey... let a young kid have his dream. ;-)
>
> Regards,
>
> Prot
>
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--
 -Jim
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