On Sat, 7 May 2016 00:02:40 -0700 (PDT), Phil Allison
wrote:
Jeff Liebermann wrote:
After some provocation by Phil Allison, I ran a temperature test on
various electrolytic capacitors:
http://802.11junk.com/jeffl/Electrolytic-cap-test/
Simple setup:
http://802.11junk.com/jeffl/Electrolytic-cap-test/test-setup.jpg
** You went to lot of trouble to see the obvious.
Cap-B was one that had failed with high ESR. There was plenty of data
and anecdotal evidence on how a normal capacitor would act. I wanted
to see how a defective capacitor acted. I also wanted to see how the
ESR meter functioned with small value and size (0.22uF 50v) caps,
which was Cap-D. The change in ESR with temp was far less radical
than the others.
http://802.11junk.com/jeffl/Electrolytic-cap-test/Cap-D.jpg
I also found as similar problem with high capacitance values (1800uF
6.3v) which was Cap-A, where the lower limit capability of the ESR
meter (about 0.03 ohms) also caused the graph to flat line. I didn't
mention this in your previous discussion on the matter, but I was
trying to determine if it made sense to use a fixed 100KHz sine wave
signal, and whether higher or lower frequencies might help test a
wider range of capacitance values. I have a pathological aversion to
accepting the obvious, and will take the time to test the obvious,
which invariably produce surprises.
All I did was try a few 450V electros, heat them with a hot air
gun until they were darn uncomfortable to hold and note that in
every case the ESR reading had plumeted by 5 to 10 times.
I wasn't interested in high voltage electrolytics. There are usually
two of those in a typical ATX power supply. They never seem to fail.
It's the low voltage electrolytics, that inhabit the output filters
and regulator circuitry that fail and were of interest to me. I
probably could have done it using your method, but I thought a hot
water bath was more interesting and accurate.
There are a number of different ESR meters available.
** I use the same one as in your pics - the Bob Parker design. He
lives not far from me and we have conversed about that an many
other electronics matters.
Yep. It's an impressive instrument, quite accurate, but a little
tricky to build (Dick Smith kit version). Methinks the later "blue"
variety might be better.
http://anatekinstruments.com/products/fully-assembled-anatek-blue-esr-meter-besr
Have you tried your meter to test the ESR of cells ?
Easy to tell if a Lithium memory cell is good or not - also good on
NiCds, NiMH and alkalines.
One of the common modifications to the original ESR meter is to add
two back to back power diodes across the input to protect the meter
from residual voltages. The problem with doing that is that the
diodes short out the battery. Since I expected to be testing far more
capacitors than batteries, this made sense.
I also have a Capacitor Wizard ESR meter that I picked up cheap at a
flea market:
http://anatekinstruments.com/products/capacitor-wizard-esr-tester-cap1b
http://anatekinstruments.com/products/capacitor-wizard-esr-tester-with-capsvr-module-cap1b-capsvr
The CapSRV model has the same diode protection circuit making it
useless for battery measurements. There's nothing particularly
wonderful about this meter except that it's very fast and convenient.
One problem is that I seem to have misplaced it and can't seem to find
it. Argh.
I also have a Peak Atlas ESR70 "purple" ESR meter.
http://www.peakelec.co.uk/acatalog/jz_esr70.html
It has a built in discharge resistor to help deal with charged
capacitors and therefore is useless for testing battery ESR.
Bottom line is that I don't use any of my ESR meters to test
batteries. I probably should build or buy something specifically for
the purpose to see what I'm missing. All of my battery testing
involve small rechargeable batteries, a discharge tester, and
computized graphs such as:
http://802.11junk.com/jeffl/LiPo/Ultrafire%2018650%20test.jpg
http://802.11junk.com/jeffl/LiPo/Ultrafire%20LiPo%203000%20ma-hr%2018650%20test.jpg
However, I'm getting into larger cells and sealed packs, where an ESR
tester is quicker and probably more useful.
Also reads low value resistors, even if there is an inductor or
transformer winding across one.
Yep. I've used that to determine the value of a charred resistor.
Usually, it's a wire wound resistor with a break somewhere along the
winding. I measure from one lead to the middle of the winding. One
end is usually open, while the other end reads half the resistor
value. However, testing electrolytics is my main use for an ESR
meter.
.... Phil
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558