Gould Biomation K-105D Logic Analyzer Available

From: Brent Hilpert <hilpert_at_cs.ubc.ca>
Date: Sat Dec 20 05:12:57 2003

Jochen Kunz wrote:
>
> On Thu, 18 Dec 2003 21:10:49 +0000 (GMT)
> ard_at_p850ug1.demon.co.uk (Tony Duell) wrote:
>
> > I picked up a K100D rather cheaply without pods.
> [...]
> > Well, 99% of my work is at
> > TTL levels, and it didn't take too long to wire up some 10124 TTL to
> > ECL level shifters to make a TTL-only pod.
> I did the same with a Dolch Logic Instruments (DLI) Logic Analyzer. A
> 300 MHz LA for nothing out of a dumpster is nice. It took some time to
> get the TTL=>ECL chips, but this machine is worth the time to make new
> pods.
> --

I can't say I have done it, but an alternative to using (and finding) TTL->ECL chips would be to use standard voltage comparators. Devices such as the LM319 (dual high speed (80nS) comparator) could be set up with the comparators' ground at -5.2V and their supply at +5V (10.2V total supply for the comparators). One input to a comparator is a signal input, the other wired to a common voltage divider setting a switching threshold (hysteresis might be added with some more resistors, or use the threshold from the analyser). A resistor or two should should complete the interfacing between the comparator output and ECL input.

This would have the added advantage of placing a far smaller load on the signal lines being tested. (A comparator input is a high impedance compared to the (rather large) load of a TTL input. (In the absence of ref data at hand I'm presuming TTL->ECL converter inputs are one TTL load.))
Received on Sat Dec 20 2003 - 05:12:57 GMT