15 Jun
2006
15 Jun
'06
10:25 p.m.
[Analogue .vs. ditial multimeter]
(grin) Agreed. I've got a Fluke 8840A and it is
really hard
to NOT wait for every digit on the display to settle down!
OTOH, if I pull out my Simpson 260P, the needle ballistics
are damped enough that you get a pretty quick "feel" for what
the number is.
Yep. Trying to get some voltate to maximum or minimum is a right pain
with a digital meter :-)
Oen other point. Most good digital meters are autoranging. Make sure you
can lock it on a particular range (or seleect the ranges manually, or
both). Habing it switch ranges and shift the desimal point halfway
through a measurement will drive you insane. As will waiting for it to go
from the highest resistance range to the lowest when
you're doing
continuity checks (think about it...)
>>> 2) A logic probe
[...]
Of course, it really works best with traditional TTL
instead
of newer logic families (but, it's good enough to give you
a quick indication of "dead" lines, etc.
One of the advantages of the LogicDart is that you have selectable
tresholds on the inputs. OK, all three channels have to be set to the
same threshold (it's actually quite rare that this causes a problem). The
insturemtn has pre-defined thresholds for TTL, 3.3V and 5V CMOS and ECL,
and you can also select your own (I used it to debug the -15V discrete
transistor logic in the HP9100, for example).
]...]
Problem with most logic analyzers is getting all the
microhooks
(or easyhooks) that go with it. Without having to sell a kidney!
Tell me about it. Unless you're insane (as I am), don't get a logic
analyser without the 'pods'. Making those is an interesting exercise in
high-speed analouge design. And only consider doing it if you know --
exactly -- the input spec of the main analyser unit
As regards the clips, I was lucky, Greenweld (back when they were in
Southampton) had some at a silly price (\pounds 1.00 for 10 or
something). I bought their entire stock [1] and passed them on to
friends, etc (no I don't have an more left, only the ones I need for my
own alanyser)
[1] I did the same thing when they had brand new, boxed, Emulex Q-bus
SCSI cards foe \pounds 10.00 each. I bought one, showed it to the system
manager wehre I was working (he was a serious DEC heed), and he basically
told me to go back the next day to buy the rest. I did. Again, I only
have a couple left for my own PDP11s....
-tony