19 Dec
2003
19 Dec
'03
9:12 p.m.
Jochen Kunz wrote:
On Thu, 18 Dec 2003 21:10:49 +0000 (GMT)
ard(a)p850ug1.demon.co.uk (Tony Duell) wrote:
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.))
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.
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