3 Nov
1999
3 Nov
'99
9:20 a.m.
From: "Richard Erlacher"
<edick(a)idcomm.com>
If you have a diode of any kind which behaves more as a resistor and less as
a diode, i.e. it measures more or less the same in both directions, though
differently on different settings on your DMM, I'd say it's broken.
I'd say you have a modern meter, and neither of you knows how to use
it. The "diode" range on the meter is there because the other
resistance ranges are not useful for testing diodes. Read the manual
for the meter, or buy a curve tracer, or build a continuity tester from
an old flashlight (two-cell preferred), or ...
I'm curious. Have you tried the same family of (mostly misleading)
tests on a known-good, plain-old silicon diode?
> From: jpero(a)cgocable.net
<jpero(a)cgocable.net>
> ...
> says "good" but I know it's very low current also low voltage so that
> would usually not screen out sick diodes.
The current and voltage for the resistance ranges are probably much
lower, which is why the readings are so useless. (Repeat previous rant
here.)
That why I used resistance ranges just to be sure.
This must be some new meaning of "sure".
There are some subtle defects possible in a diode which will not be
revealed by the "diode" test on a multimeter, but that's almost
certainly the best test offered by the meter.
Wizard
Apparently a misnomer.
------------------------------------------------------------------------
Steven M. Schweda (+1) 651-645-9249 (voice, home)
1630 Marshall Avenue #8 (+1) 612-754-2636 (voice, work)
Saint Paul MN 55104-6225 (+1) 612-754-6302 (facsimile, work)
sms(a)antinode.org sms(a)provis.com (work)
3 Nov
3 Nov
10:10 a.m.
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5:47 a.m.
Date: Thu, 4 Nov 1999 00:10:57 +0000 (GMT)
Reply-to: classiccmp(a)u.washington.edu
From: ard(a)p850ug1.demon.co.uk (Tony Duell)
To: "Discussion re-collecting of classic computers"
<classiccmp(a)u.washington.edu>
Subject: Re: schottky diode again..
Have you tried reading the 'manuals' for most
modern meters (or other
test gear)? They're useless for actually telling you what the instrument
is doing. At one time, such manuals contained schematics, simplified
schematics, circuit descriptions, etc. Not any more :-(
Tony as usual is right. I don't read those modern manuals these
days. Except skimming for few areas just to be sure.
Surely the sort of person who buys a multimeter is also the sort of
person who can read/understand a schematic. So the lack of such
information is something of a puzzle to me.
That DMM is built by me in kit form and calibrated it for voltage and
current. Good as any normal DMM should do. Same with ESR. no
calibrating required. Zeroes when shorting and press the button
twice. One push turns on ESR, when on and probes is showing low
resistance or shorted together and pressed button again zeroes it to
account for losses in internal circuits and probe wires. That ESR
meter has real docs because it's kit and info that explains why can
most of time can measure caps in circuit. Came from Dick Electronics
(Aus) for about 40 US. The pot is only there to preset for voltage
cut off to warn of low battery condition.
For this reason, I _always_ test every feature of a new piece of test
gear, often in unconventional ways. I _will_ check diodes on resistance
ranges to see what happens. Often the lower resistance ranges _do_
provide enough current to provide a useful test on diodes, and the
ability to do the check at more than one current sometimes picks up
'rogue' diodes.
Correct as I suspected by playing.
My DMM actually shows better when I move from low res scales to mid
to high ranges. I need to grab another meter to see what it do on my
dmm. :-) Tony inpsired me to this!
-tony
Wizard
11:08 a.m.
On Wed, 3 Nov 1999 sms(a)antinode.org wrote:
Bored, Steve? Off your meds? Or should I just be silent before
the Master and snatch whatever crumbs of Engineering knowledge you
may see fit to bless us with in the future.... couched as they
might be in the sneering disdain of intellectual superiority?
Is there any more concerning Semiconductor Diodes, Their Thoery
and Application, that we grovelling unwashed should try and
understand? Is there anything about the physics... the chemistry...
the electronics... the mechanics... of these devices that you can
somehow help us with? Or are we to just give up and dabble no
further in Things that don't concern us?
In light of the tacit proclamation of your superior Diode
Understanding, I will await your wisdom and try and not pollute the
list with my own mis-understanding... far be it from someone to
*help* me learn.
From:
"Richard Erlacher" <edick(a)idcomm.com>
If you have a diode of any kind which behaves more as a resistor and less as
a diode, i.e. it measures more or less the same in both directions, though
differently on different settings on your DMM, I'd say it's broken.
I'd say you have a modern meter, and neither of you knows how to use
it. The "diode" range on the meter is there because the other resistance ranges are not useful for testing diodes.
Read the manual
for the meter, or buy a curve tracer, or build a continuity tester from
an old flashlight (two-cell preferred), or ...
Ever consider that the people who populate this list come from
many disparate disciplines and experience? Does it somehow escape you
that (gasp!) not all of us are PhD-level engineers? Is it possible
that my newsreader has misplaced the diagrams that you might have
included re: the above devices that you so casually chide us to posses?
I'm curious. Have you tried the same family of (mostly misleading)
The current and voltage for the resistance ranges are probably much
lower, which is why the readings are so useless.
And just *why* is that, O Master? Or do we just take your word
for it and go in silent faith and sin no more...
(Repeat previous rant
here.)
See comments above re: your repeat previous rant.
> That why I used resistance ranges just to be sure.
This must be some new meaning of "sure".
Apparently an ad-hominem *personal* attack on a Listmember who has
given hours of time and patient knowledge to myself and many, many
others on this list of *HOBBYISTS*, Steven... And your contributions
are archived... where?
Man... Steve, old buddy... are you having a Real Bad Day and
just lost your cool, or is this the real Steve?
I certainly won't respond to any more stuff like this from you,
save with a deletion mark, and on to the next... not that you might
care much.
Cheers
John
(Snipped fat sig with much personal data)
I grant you this, Schweda: at least you don't hide behind anything
when you smack people...
Wizard
Apparently a misnomer.
9181
days inactive
9181
days old
3 comments
4 participants
participants (4)
-
ard＠p850ug1.demon.co.uk -
jpero＠cgocable.net -
jpl15＠netcom.com -
sms＠antinode.org