sci.electronics.repair@googlegroups.com

Today's topics:

* Power transistor question... - 6 messages, 3 authors
http://groups.google.com/group/sci.electronics.repair/t/48e3a91c572ef00c?hl=en
* Wall Warts - 1 messages, 1 author
http://groups.google.com/group/sci.electronics.repair/t/de407a5056a54ee0?hl=en
* NiMH new battery conditioning - 4 messages, 2 authors
http://groups.google.com/group/sci.electronics.repair/t/642feb09361f607e?hl=en

==============================================================================
TOPIC: Power transistor question...
http://groups.google.com/group/sci.electronics.repair/t/48e3a91c572ef00c?hl=en
==============================================================================

== 1 of 6 ==
Date: Mon, May 30 2011 6:16 pm
From: "Phil Allison"

"Jeff Liebermann"
"Phil Allison"
>
> The problem with the Extech 380193 Handheld LCR meter is that it will
> measure ESR at 120Hz and 1KHz. ESR is usually measured at about
> 100KHz. Dave Jones mentions this at about 12-13 minutes into his
> video. This is because electrolytic cazapitors exhibit a minimum ESR
> around 100Khz.
> <http://www.amccaps.com/leaded-capacitors/switch-mode-ceramic-capacitors/esr-vs-frequency.html>

** Gotta pick you up on this one !!

That link shows ESR curves with frequency of a couple of * CERAMIC *
capacitors of unusually high values.

ESR meters intended for in circuit testing of electros by service techs
simply measure the cap's IMPEDANCE at around 100kHz. At this frequency -
all but the lowest value electros have their minimum impedances and the
values obtained are very close to ESR values at the same frequency. This
allows one to compare electros for (high frequency) ESR and pick out faulty
examples very easily.

OTOH, the Extech meter is designed to measure L and C values for a wide
range of inductors and capacitors and uses to standard test frequency of
1kHz as used in countless other instruments. This means it is NOT intended
to perform in-circuit testing of L and C value as other circuitry that may
be in parallel may spoil the readings.

However, in the case of electros with values from say 4.7 uF and upwards and
fitted to a TV set I would expect readings to be OK and the ESR values
obtained to be useable. It would be a good idea to re-test any electros
that are removed cos the ESR reading seemed high.

IMO - the 120 Hz frequency should only be used for out of circuit testing.

..... Phil

== 2 of 6 ==
Date: Mon, May 30 2011 7:17 pm
From: "Phil Allison"

"Meat Plow"

>> http://www.youtube.com/watch?v=zEA5MfllPdg
>
> Not a bad little meter for the $$$$. Anyone who does work on consumer
> electronics ought to have one or something similar. Removes a lot of
> guess work.

** I disagree.

An LCR meter is more useful for design and production than in servicing.

Many low cost DMMs include capacitance ranges that can measure from a few pF
up to 200 or 2000uF.

A dedicated ESR meter handles electros just fine while in circuit - and
lets you test all kinds of cells too, which an LCR meter often cannot.

Any DMM can read the resistance of an inductor or transformer winding.

The only function left is to measure inductors for value.

.... Phil

== 3 of 6 ==
Date: Mon, May 30 2011 7:29 pm
From: Jeff Liebermann

On Tue, 31 May 2011 11:16:04 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

>> The problem with the Extech 380193 Handheld LCR meter is that it will
>> measure ESR at 120Hz and 1KHz. ESR is usually measured at about
>> 100KHz. Dave Jones mentions this at about 12-13 minutes into his
>> video. This is because electrolytic cazapitors exhibit a minimum ESR
>> around 100Khz.
>> <http://www.amccaps.com/leaded-capacitors/switch-mode-ceramic-capacitors/esr-vs-frequency.html>

>That link shows ESR curves with frequency of a couple of * CERAMIC *
>capacitors of unusually high values.

Oops, y'er right. Sorry(tm).

Oddly, while the ESR of the ceramic caps are much lower than
electrolytics, the curve shapes seem to be similar.

Googling, I find:
<http://www.low-esr.com/esrfreqperfcurves.asp>
Note the dip in ESR and loss tangent at around 100KHz on various
graphs.

>ESR meters intended for in circuit testing of electros by service techs
>simply measure the cap's IMPEDANCE at around 100kHz. At this frequency -
>all but the lowest value electros have their minimum impedances and the
>values obtained are very close to ESR values at the same frequency. This
>allows one to compare electros for (high frequency) ESR and pick out faulty
>examples very easily.
>
>OTOH, the Extech meter is designed to measure L and C values for a wide
>range of inductors and capacitors and uses to standard test frequency of
>1kHz as used in countless other instruments. This means it is NOT intended
>to perform in-circuit testing of L and C value as other circuitry that may
>be in parallel may spoil the readings.
>
>However, in the case of electros with values from say 4.7 uF and upwards and
>fitted to a TV set I would expect readings to be OK and the ESR values
>obtained to be useable. It would be a good idea to re-test any electros
>that are removed cos the ESR reading seemed high.
>
>IMO - the 120 Hz frequency should only be used for out of circuit testing.

Yep. Agreed on all points.

>..... Phil

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 4 of 6 ==
Date: Mon, May 30 2011 8:31 pm
From: "Phil Allison"

"Jeff Liebermann"
"Phil Allison"
>
>>That link shows ESR curves with frequency of a couple of * CERAMIC *
>>capacitors of unusually high values.
>
> Oops, y'er right. Sorry(tm).
>
> Oddly, while the ESR of the ceramic caps are much lower than
> electrolytics, the curve shapes seem to be similar.
>
> Googling, I find:
> <http://www.low-esr.com/esrfreqperfcurves.asp>
> Note the dip in ESR and loss tangent at around 100KHz on various
> graphs.

** I see no such trend for the electros.

The ESR of most electros is almost constant down to about 500Hz, then rises
to a few times its high frequency value at 50Hz. I believe mobility of the
ions in the electrolyte is the cause.

Electros uniquely have very low Q factors - which means their impedance *
stays low * over a very wide frequency range.

A typical 470uF electro has an impedance under 0.1 ohms from 4kHz to 1MHz as
does the 330uF example in the graphs.

High Q capacitors ( film and ceramic) all have sharp impedance dips at self
resonance.

.... Phil

== 5 of 6 ==
Date: Mon, May 30 2011 8:46 pm
From: "Dave"

"Phil Allison" <phil_a@tpg.com.au> wrote in message
news:94j1ebFms1U1@mid.individual.net...
>
> "Meat Plow"
>
>>> http://www.youtube.com/watch?v=zEA5MfllPdg
>>
>> Not a bad little meter for the $$$$. Anyone who does work on consumer
>> electronics ought to have one or something similar. Removes a lot of
>> guess work.
>
>
> ** I disagree.
>
> An LCR meter is more useful for design and production than in servicing.
>
> Many low cost DMMs include capacitance ranges that can measure from a few
> pF up to 200 or 2000uF.
>
> A dedicated ESR meter handles electros just fine while in circuit - and
> lets you test all kinds of cells too, which an LCR meter often cannot.
>
> Any DMM can read the resistance of an inductor or transformer winding.
>
> The only function left is to measure inductors for value.
>
>
> .... Phil
>

Wanted to thank *everyone* for the info and encouragement I have received in
this discussion. Bottom line for me, at least for now, is simply don't test
in-circuit (pop one lead and then test after discharging). Have also found
a ton of material on youtube and the net that convinces me to get a
dedicated ESR meter (or possibly build one.) Anyway, thanks all for a very
enlightening discussion.

Take it easy...

Dave

== 6 of 6 ==
Date: Mon, May 30 2011 8:52 pm
From: "Phil Allison"

"Dave"
>
> Wanted to thank *everyone* for the info and encouragement I have received
> in this discussion. Bottom line for me, at least for now, is simply don't
> test in-circuit (pop one lead and then test after discharging). Have also
> found a ton of material on youtube and the net that convinces me to get a
> dedicated ESR meter (or possibly build one.) Anyway, thanks all for a
> very enlightening discussion.

** This is the one I would buy - if I did not already have two of Bob's
earlier designs.

http://www.anatekcorp.com/blueesr.htm

BTW

Bob is an old mate of mine.

.... Phil

==============================================================================
TOPIC: Wall Warts
http://groups.google.com/group/sci.electronics.repair/t/de407a5056a54ee0?hl=en
==============================================================================

== 1 of 1 ==
Date: Mon, May 30 2011 6:18 pm
From: Jeff Liebermann

On Mon, 30 May 2011 15:14:17 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> wrote:

>"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
>news:a4u7u69f03pb04a2o3j3jjbdh9msv9r4ih@4ax.com...
>
>> I also use NiMH batteries in my various cameras (Canon S5IS etc) all
>> of which use AA cells. I'm seeing the typical 1%/day self-discharge
>> rate. I keep two sets of batteries in the bag. It's not unusual for
>> me to find the spares to be nearly dead after about 2 months.
>
>> Your NiMH milage may vary, but mine sucks.
>
>Weird. Which brands do you use? I use mostly MAHA (PowerEx).

Yeah, I know I'm weird. I use a random assortment of whatever I
blunder across. Costco has Sanyo Eneloop, so I have a pile of those.
I just found several 4 packs of Energizer 2300ma-hr NiMH cells, so I
guess I'll use those. I have no idea what's in the camera or in the
bottom of the bag, but I'll guess is some no-name brand I picked up at
a ham radio flea market. I just found some Duracel 2050ma-hr cells.
Oh swell, a pair of Lenmar NoMem Pro 1500 ma-hr cells in my emergency
bag. Nice mess (and proud of it).

I've been running some battery tests on the new batteries for the last
4 hrs to see if I can find any "conditioning" effects. Stay tunes.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

==============================================================================
TOPIC: NiMH new battery conditioning
http://groups.google.com/group/sci.electronics.repair/t/642feb09361f607e?hl=en
==============================================================================

== 1 of 4 ==
Date: Mon, May 30 2011 9:18 pm
From: Jeff Liebermann

Per a previous discussion, I decided to test whether new NiMH
batteries need to be conditioned or charged several times before
reaching their rated capacity. Apparently they do.

The test setup is a West Mtn Radio CBA-IIv1 battery analyzer.
<http://802.11junk.com/jeffl/NiMH/cba-II.jpg>
I didn't want to wait 20 hrs per test to get the official rated
capacity, so I elected to run the tests at 1C which resulted in about
a 45 minute test, but also resulted in a much lower capacity result.
It also caused some unexpected errors. The design of the CBA-II does
not include a Kelvin probe connection to eliminate any losses in the
cables and connectors. It measures the voltage at the load, instead
of at the battery. This is not a problem at low load currents, but at
2 amps, results in considerable error.

Two new (out of the package) batteries were used. An Energizer NiMH
2300 ma-hr cell, and a Duracell 2050 ma-hr cell. Between tests, the
batteries were quick charged in a Radio Shack 23-1305 NiMH quick
charger (15 min). Each battery was discharged 3 times and the
discharge curves plotted.

Note that the Energizer package says 2450 ma-hr, while the battery is
marked 2300 ma-hrs.
<http://802.11junk.com/jeffl/NiMH/energizer.jpg>

The Energizer cell showed no change in capacity between discharges.
<http://802.11junk.com/jeffl/NiMH/Energizer-NiMH-2300.jpg>
Using 1.0VDC as the end point, the measured cell capacity is:
Run 1 1785 ma-hr
Run 2 1890 ma-hr
Run 3 1895 ma-hr

The Duracell cell showed a larger change.
<http://802.11junk.com/jeffl/NiMH/Duracelll-NiMH-2050.jpg>
Using 1.0VDC as the end point, the measured cell capacity is:
Run 1 1200 ma-hr
Run 2 1270 ma-hr
Run 3 1385 ma-hr

The net improvement over 3 charge-discharge runs is about 10% for the
Energizer and 15% for the Duracell. Not huge, but certainly
measurable. Whether it is worth the effort conditioning the battery
before use, is debatable.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 2 of 4 ==
Date: Mon, May 30 2011 9:37 pm
From: "Phil Allison"

"Jeff Liebermann"
>
> Per a previous discussion, I decided to test whether new NiMH
> batteries need to be conditioned or charged several times before
> reaching their rated capacity. Apparently they do.
>
> The test setup is a West Mtn Radio CBA-IIv1 battery analyzer.
> <http://802.11junk.com/jeffl/NiMH/cba-II.jpg>
> I didn't want to wait 20 hrs per test to get the official rated
> capacity, so I elected to run the tests at 1C which resulted in about
> a 45 minute test, but also resulted in a much lower capacity result.
> It also caused some unexpected errors. The design of the CBA-II does
> not include a Kelvin probe connection to eliminate any losses in the
> cables and connectors. It measures the voltage at the load, instead
> of at the battery. This is not a problem at low load currents, but at
> 2 amps, results in considerable error.
>
> Two new (out of the package) batteries were used. An Energizer NiMH
> 2300 ma-hr cell, and a Duracell 2050 ma-hr cell. Between tests, the
> batteries were quick charged in a Radio Shack 23-1305 NiMH quick
> charger (15 min). Each battery was discharged 3 times and the
> discharge curves plotted.
>
> Note that the Energizer package says 2450 ma-hr, while the battery is
> marked 2300 ma-hrs.
> <http://802.11junk.com/jeffl/NiMH/energizer.jpg>
>
> The Energizer cell showed no change in capacity between discharges.
> <http://802.11junk.com/jeffl/NiMH/Energizer-NiMH-2300.jpg>
> Using 1.0VDC as the end point, the measured cell capacity is:
> Run 1 1785 ma-hr
> Run 2 1890 ma-hr
> Run 3 1895 ma-hr
>
> The Duracell cell showed a larger change.
> <http://802.11junk.com/jeffl/NiMH/Duracelll-NiMH-2050.jpg>
> Using 1.0VDC as the end point, the measured cell capacity is:
> Run 1 1200 ma-hr
> Run 2 1270 ma-hr
> Run 3 1385 ma-hr
>
> The net improvement over 3 charge-discharge runs is about 10% for the
> Energizer and 15% for the Duracell. Not huge, but certainly
> measurable. Whether it is worth the effort conditioning the battery
> before use, is debatable.

** You got something against NiMh cells ?

I would never mistreat NiMH AA cells the way you just have.

15 minute charging is absurd for any cell NOT designed for such abuse - it
causes overheating with new cells and destruction of older ones.

A 1C discharge test will never give the rated capacity figure with NiCd or
NiMH.

IME - the idea that new cells have a "running in "period is a MYTH
invented by retailers back in the 1970s when consumers were first sold AA
and C size NiCds and found their performance disappointing when compared to
alkalines.

The inherent lower terminal voltage and cell mAH capacity were the real
reasons.

.... Phil

== 3 of 4 ==
Date: Mon, May 30 2011 10:38 pm
From: Jeff Liebermann

On Tue, 31 May 2011 14:37:43 +1000, "Phil Allison" <phil_a@tpg.com.au>
wrote:

>** You got something against NiMh cells ?

Yep. I don't like them.

>I would never mistreat NiMH AA cells the way you just have.

I didn't have time to do it the right way (20 hr discharge). I can do
it again with a longer discharge time and lower current. I still have
several of both brand of cells that I haven't mistreated yet. However,
it will take about a week to produce results (plus dragging home a
spare computah to do the test and building a better battery holder).

>15 minute charging is absurd for any cell NOT designed for such abuse - it
>causes overheating with new cells and destruction of older ones.

True for the Duracell, which recommends 205ma for 15 hrs to recharge
printed on the cell. The Energizer Recharge battery doesn't specify a
charge current:
<http://data.energizer.com/PDFs/nh15-2000.pdf>
However, the recommended battery charger is a quick charger:
<http://data.energizer.com/PDFs/ch15mn2.pdf>
with a 15 minute charge time.

I've been testing batteries since about 2005 while working on a
product that I won't discuss. However, I will point out that many
NiCd batteries can be quick charged at ridiculously high rates, as
long as certain (unspecified) conditions are met. If you don't mind,
I'll leave this unsubstantiated.

Incidentally, the Sanyo ENELOOP battery data sheet recommends fast
charging at 2A for 1.1 hrs:
<http://www.eneloop.info/fileadmin/EDITORS/ENELOOP/DATA_SHEETS/HR-3UTGA_data_sheet.pdf>

>A 1C discharge test will never give the rated capacity figure with NiCd or
>NiMH.

I indicated that in my posting as:

> I didn't want to wait 20 hrs per test to get the official rated
> capacity, so I elected to run the tests at 1C which resulted in about
> a 45 minute test, but also resulted in a much lower capacity result.

The purpose of the test was to see if a brand new battery required
several charge-discharge cycles before it would deliver full capacity,
not to measure the actual rated capacity in a 20 hr discharge test.

>IME - the idea that new cells have a "running in "period is a MYTH
>invented by retailers back in the 1970s when consumers were first sold AA
>and C size NiCds and found their performance disappointing when compared to
>alkalines.

Maybe. There was also quite a bit of effort in the mid 1990's by
manufactures to differentiate their NiMH products from NiCd. For
example, I found a pair of Lenmar NoMEM Pro NiMH batteries, which are
an obvious shot at the alleged NiCd "memory effect". Another
possibility is that some support droid needed a line to get rid of a
complaining customer and invented the "conditioning" for the purpose.

>The inherent lower terminal voltage and cell mAH capacity were the real
>reasons.

Agreed. I went through the mess with alleged "9V" (6 cell) NiCd
batteries, being more like 7.2VDC. With a nominal operating voltage
for 1.2 to 1.3 VDC for NiCd and NiMH, anything designed for a 1.5VDC
alkaline is going to have a problem.

Incidentally, all of the marine radios I helped design were required
to function down to 10.0VDC applied power. They couldn't reach rated
TX power at 70% of rated voltage, but still had to belch at least a
few watts of RF and remain functional.

I'm rather mystified by the results. Although the improvement in
capacity after 3 charge-discharge cycles is minor (10-15%), it still
seems for real. My previous tests didn't show such an increase in
capacity. Instead, it showed a deterioration in capacity. However, I
was testing for something quite different, and was working with a mix
of old and new cells.

--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

== 4 of 4 ==
Date: Mon, May 30 2011 10:57 pm
From: "Phil Allison"

"Jeff Liebermann"
>
>>** You got something against NiMh cells ?
>
> Yep. I don't like them.

** Wanker.

>>I would never mistreat NiMH AA cells the way you just have.
>
> I didn't have time to do it the right way (20 hr discharge).

** The 15 min charging was the abuse - fool.

> I can do
> it again with a longer discharge time and lower current.

** The 15 min charging was the abuse - fool.

>>15 minute charging is absurd for any cell NOT designed for such abuse - it
>>causes overheating with new cells and destruction of older ones.
>
> True for the Duracell,

** True for all of them - fool.

> However, the recommended battery charger is a quick charger:
> <http://data.energizer.com/PDFs/ch15mn2.pdf>
> with a 15 minute charge time.

** They would - since they sell the fucking things.

Energiser sell a whole range of chargers designed to destroy NiMh cells.

Means they sell more cells.

> I've been testing batteries since about 2005

** I've been doing it since 1979.

> However, I will point out that many
> NiCd batteries can be quick charged at ridiculously high rates,

** Only a rare few, specially designed NiCds were designed for it -
Sanyo's red " F " cells being one.

The issue is the HIGH probability of OVERCHARGING and hence over heating
with consequent internal damage.

> Incidentally, the Sanyo ENELOOP battery data sheet recommends fast
> charging at 2A for 1.1 hrs:
> <http://www.eneloop.info/fileadmin/EDITORS/ENELOOP/DATA_SHEETS/HR-3UTGA_data_sheet.pdf>

** Got nothing to do with a 15 minute charge in a cheap POS charger like you
did.

>>A 1C discharge test will never give the rated capacity figure with NiCd or
>>NiMH.
>
> I indicated that in my posting as:
>
>> I didn't want to wait 20 hrs per test to get the official rated
>> capacity, so I elected to run the tests at 1C which resulted in about
>> a 45 minute test, but also resulted in a much lower capacity result.

** Will you admit to being a raving lunatic ???

And save me the trouble of demonstrating it to the world over and over.

>>IME - the idea that new cells have a "running in "period is a MYTH
>>invented by retailers back in the 1970s when consumers were first sold AA
>>and C size NiCds and found their performance disappointing when compared
>>to
>>alkalines.
>
> Maybe.

** Definitely.

>>The inherent lower terminal voltage and cell mAH capacity were the real
>>reasons.
>
> Agreed.

** No elaboration was needed.

> I'm rather mystified by the results.

** Bad science is no mystery.

..... Phil

==============================================================================

You received this message because you are subscribed to the Google Groups "sci.electronics.repair"
group.

To post to this group, visit http://groups.google.com/group/sci.electronics.repair?hl=en

To unsubscribe from this group, send email to sci.electronics.repair+unsubscribe@googlegroups.com

To change the way you get mail from this group, visit:
http://groups.google.com/group/sci.electronics.repair/subscribe?hl=en

To report abuse, send email explaining the problem to abuse@googlegroups.com

==============================================================================
Google Groups: http://groups.google.com/?hl=en