audio recording on IC -help wanted

[Dave Platt]

They will do this in DC circuits if installed backwards,
or if excessive valtage is applied.
I have used 2 to replace 1 NP cap in DC circuits but
have never attempted it for a pure AC circuit.
Did you measure the AC waveform P-P or RMS?
P-P would be the only way and allow a large spread
between peak and cap voltage rating, like 2X.
Your test may not have allowed for excessive voltage
or it may do the same again.

I'd guess that it wasn't a matter of overvoltage - it was a matter of
ripple current, and the resulting heat dissipation.

Running a large AC current through a 'lytic cap is generally a bad
idea. Aluminum electrolytics have a relatively high dissipation
factor... their equivalent series resistance is fairly high and
they'll heat up rapidly if high currents are run through them.

I'd guess that the OP didn't puncture the dielectric (as an
overvoltage would have done) - he boiled the electrolyte into steam.

--
Dave Platt <dplatt@radagast.org> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Jeff]

I just tried the same "test" with the same value caps
and a 5 ohm resistor it has been sitting at 11V AC RMS
for a lot longer than 10 seconds. (varriac)
Very little current draw and nothing getting hot or
exploding, RMS voltage across each cap ~5.5VAC
Now for the surprise, DC reading across each cap
6-7VDC polarized + and- with each capacitor.
Jeff

"Robert Monsen" <nospam@nowhere.com> wrote in message
news:2WDTa.130452$Ph3.16933@sccrnsc04...

Actually, once I started cleaning up the mess from the explosion, I
realized
that BOTH had exploded. The reason I didn't notice is that one only
sprayed
electrolyte. The CAN exploded on the other one. This is NOT a good way to
hook up capacitors, and will serve as a lesson to me to be careful with
polarized electrolytics during circuit failure modes. It took less than 10
seconds to blow it up.

Regards,
Bob Monsen

"Robert Monsen" <nospam@nowhere.com> wrote in message
news:qPDTa.130389$Ph3.16509@sccrnsc04...
I just tried to do your experiment, since it seemed absurd to me (how
could
one side charge without passing charge the wrong way through to the
other
side?) 14v of AC (off of a step down transformer) across two back to
back
(positive side out) 100uF 25v polarized capacitors.

I should have been wearing safety goggles. I was just about to hook up
the
oscilloscope to check out this mysterious DC bias, when one of the 100uf
capacitors exploded right in front of me. I've never seen that before!
Its
amazing how much stuff sprayed out all over the place. They were both
brand
new. The electrolyte got all over my new tek probes and superstrip!

Regards,
Bob Monsen

"Jim Meyer" <jmeyer@nektonresearch.com> wrote in message
news:21ede509.0307230831.68589965@posting.google.com...
"Robert Monsen" <nospam@nowhere.com> wrote in message
news:<6W1Ta.115655$ye4.85380@sccrnsc01>...
From what I can determine by searching the web (references below), I
believe
that nonpolarized electrolytic capacitors are actually electrolytic
capacitors in which the dielectric oxide layer has been formed on
both
the
anode and cathode during the manufacturing process. In a polarized
electrolytic capacitor, only the anode has this dielectric oxide
layer
(actually, the cathode has it also, except its too thin to withstand
more
than about 2V. This, I gather, is for protection in the case of an
accidental reverse bias.)

Thus, I believe its probably not a good idea to put electrolytic
capacitors
back to back, as suggested previously.

Regards
Bob Monsen

This comes up about once every two or three years.

It *IS* OK to put two polarized caps back-to-back to make an AC
cap out of them. The reason is that there is a tiny bit more leakage
in the reverse biased cap. That leakage charges the "properly" biased
cap in the right direction to keep it happy when the current reverses.
Since the circuit is symetrical, each cap's leakage protects the
other.

Do a test with real capacitors (or even a SPICE simulation). You
will find that after only a couple of cycles that each cap will have a
DC voltage across it that is of a magnitude and polarity such that it
will be completely protected from reverse voltages.

You can guild the lilly with a couple of diodes. One diode
across each cap in a direction that will prevent the cap's voltage
from going more than a diode's drop reverse biased. The diodes are
not necessary but may give you that belt and suspenders feeling of
confidence.

Jim

 

[Robert Monsen]

One of the earlier posters suggested that there is some kind of leakage
effect that pumps the junction between the capacitors up to a high dc level,
high enough to prevent the AC voltage from causing a reverse bias.

Given a diode over one of the capacitors pointing towards the junction, I
can see that it would get pumped up to the highest voltage, minus the .6
drop on the diode. If the diode was pointed away from the junction, then the
opposite would be true, ie, the junction would drop to the lowest voltage +
the .6 PN drop.

If there is asymetrical leakage of current, then this would also happen
without the diode, one way or another. If the asymetric leakage is toward
the junction, then the junction would pump up to the highest voltage. If its
away from the junction, then the junction would drop to the lowest voltage.

Given the above mentioned posting, my guess was that it will leak current
from - to + more readily than + to -. Thus, I put on goggles, and tried the
experiment again, this time joining the + leads rather than the - leads.
Also, I used caps with a higher voltage (50 VDC) rating. The maximum voltage
pp at any one time is about 40v, so I guessed that it should be better able
to handle the stress.

The first experiment was with a diode from the - to + terminal of one of the
caps. The DC voltage between the caps grew to 16vdc, as expected.

Next, I discharged the caps, and tried it again without the diode. The caps
did not explode, but the dc voltage seemed to land at a random place
initially, and then slowly climb. Thus, its probably true that the leakage
is greater from - to + than from + to -, at least with these new caps.
However, it seems to take a long time for these 100uf caps to charge up to a
value that will protect them from being charged with incorrect polarity
(without the diode, anyway). I let the caps charge for 30 seconds, and it
looked like they were charging at about 2v per minute. Thus, the 'bad'
polarity charging would occur in my test setup for about 7 minutes, albeit
with smaller and smaller negative voltages all the time.

I did not repeat the experiment with the caps connected in the other
direction, although by symmetry it should simply charge the negative
junction to a large negative value over time. However, I'm still pulling cap
stuffing out of my hair from the last experiment, so I though I'd leave
things as they stand... Any brave souls who want to give it a try might
email me the results at rcmonsen @ comcast.net

I'm guessing that the explosion from before occured because the leakage
current wasn't fast enough to prevent a big negative overvoltage of the
caps, or perhaps one of the caps had a big leak in the wrong direction.

I'd say that in order to replace nonpolarized caps with polarized caps, I'd
use a diode to quickly charge the junction between them up (or down). Point
the diode from the - to the + terminal over one of the caps. Not using the
diode risks an explosion, or at the least degradation of the caps over time
due to reverse voltages for a time while the system charges up.

The other point is that since the caps are in series, the total value is
C1*C1/(C1+C2), so not only do you need two caps, you need twice the value
that the original non-polarized cap had (in addition to the diode). Also,
both of these caps need to have a dc rating at least twice the peak to peak
AC voltage expected.

Regards

"Robert Monsen" <nospam@nowhere.com> wrote in message
news:2WDTa.130452$Ph3.16933@sccrnsc04...

Actually, once I started cleaning up the mess from the explosion, I
realized
that BOTH had exploded. The reason I didn't notice is that one only
sprayed
electrolyte. The CAN exploded on the other one. This is NOT a good way to
hook up capacitors, and will serve as a lesson to me to be careful with
polarized electrolytics during circuit failure modes. It took less than 10
seconds to blow it up.

Regards,
Bob Monsen

"Robert Monsen" <nospam@nowhere.com> wrote in message
news:qPDTa.130389$Ph3.16509@sccrnsc04...
I just tried to do your experiment, since it seemed absurd to me (how
could
one side charge without passing charge the wrong way through to the
other
side?) 14v of AC (off of a step down transformer) across two back to
back
(positive side out) 100uF 25v polarized capacitors.

I should have been wearing safety goggles. I was just about to hook up
the
oscilloscope to check out this mysterious DC bias, when one of the 100uf
capacitors exploded right in front of me. I've never seen that before!
Its
amazing how much stuff sprayed out all over the place. They were both
brand
new. The electrolyte got all over my new tek probes and superstrip!

Regards,
Bob Monsen

"Jim Meyer" <jmeyer@nektonresearch.com> wrote in message
news:21ede509.0307230831.68589965@posting.google.com...
"Robert Monsen" <nospam@nowhere.com> wrote in message
news:<6W1Ta.115655$ye4.85380@sccrnsc01>...
From what I can determine by searching the web (references below), I
believe
that nonpolarized electrolytic capacitors are actually electrolytic
capacitors in which the dielectric oxide layer has been formed on
both
the
anode and cathode during the manufacturing process. In a polarized
electrolytic capacitor, only the anode has this dielectric oxide
layer
(actually, the cathode has it also, except its too thin to withstand
more
than about 2V. This, I gather, is for protection in the case of an
accidental reverse bias.)

Thus, I believe its probably not a good idea to put electrolytic
capacitors
back to back, as suggested previously.

Regards
Bob Monsen

This comes up about once every two or three years.

It *IS* OK to put two polarized caps back-to-back to make an AC
cap out of them. The reason is that there is a tiny bit more leakage
in the reverse biased cap. That leakage charges the "properly" biased
cap in the right direction to keep it happy when the current reverses.
Since the circuit is symetrical, each cap's leakage protects the
other.

Do a test with real capacitors (or even a SPICE simulation). You
will find that after only a couple of cycles that each cap will have a
DC voltage across it that is of a magnitude and polarity such that it
will be completely protected from reverse voltages.

You can guild the lilly with a couple of diodes. One diode
across each cap in a direction that will prevent the cap's voltage
from going more than a diode's drop reverse biased. The diodes are
not necessary but may give you that belt and suspenders feeling of
confidence.

Jim

 

[Dieter Wiedmann]

Jerry West schrieb:

OOPS! I made a boo boo. The device is actually marked AY-1-5051
Sorry!

This is a 4 stage frequency divider made by GI, datasheet is available.
Interested in some scans?


Regards,
Dieter

 

[Jerry West]

OOPS! I made a boo boo. The device is actually marked AY-1-5051
Sorry!

Jerry

Jerry West <westerby1@lycos.co.uk> wrote in message
news:bfn0e9$adm$1@newsg4.svr.pol.co.uk...

Can anyone identify this component. It is a 10 legged device similar to an
old power transistor in shape[round silver can with a small tab]
It is one of three on a tone generator board from an electronic accordon.
It
is marked GIM

Thanks inadvance
Jerry

 

[Lewin A.R.W. Edwards]

Aha! This is something I'm not doing. I keep CE# low all the time.

Let me know if it works out!

 

[William P.N. Smith]

shoppa@trailing-edge.com (Tim Shoppa) wrote:

But I'm looking for the state-of-the-art in charging good old lead-acid
batteries (i.e. deep-cycle marine batteries and/or gel cells).

Those two different battery types are going to have somewhat different
charge voltages and current limits, but the basic idea is about the
same.

Ask in one of the alternate energy newsgroups (alt.homepower, etc)
about multi-stage battery chargers. They call them three-stage:

Constant current to a specific voltage (say 14.4V)
Constant voltage at that voltage till current drops below some
setpoint (say 200 mA)
Constant voltage float at a lower setpoint (say 13.8V).

Note that the first two "stages" are just a current limited power
supply.

Also, there are a bunch of different types of lead-acid battery, from
the standard type, to those with calcium grids, gel cells, AGM
(absorbed glass mat, essentially Gates Cyclon technology), etc. Each
has peculiarities (you have to be especially careful not to overcharge
gel and AGM batteries, as they can't be topped off) but those are
details.

--
William Smith wpns@compusmiths.com N1JBJ@amsat.org
ComputerSmiths Consulting, Inc. www.compusmiths.com

 

[Jonathan Kirwan]

On 24 Jul 2003 13:57:04 -0700, shoppa@trailing-edge.com (Tim
Shoppa) wrote:

Maxim and others now have lots of chips for "smart charging" Ni-Cads, Li ion,
and NiMH batteries. The "smart" battery packs have chips that seem to not
only sense cell temperature but have other characteristics (accumulated
charge/discharge, etc.)

But I'm looking for the state-of-the-art in charging good old lead-acid
batteries (i.e. deep-cycle marine batteries and/or gel cells). In particular,
for long-term UPS usage. The battery manufacturers I've gotten technical
data from (Panasonic and Gates/Hawker) seem to still recommend constant-
voltage float charging for this application, sometimes mentioning a temperature
coefficient for float voltage depending on cell temperature and usually
specifying a maximum charge current (not important for the 99.9% of the time
the UPS is just floating the batteries, but certainly important for
initial start-up and recovery after an outage).

Is there anything new to know beyond this? Last time I looked into the
subject (over a decade ago) it seemed pretty much the same. With all the
other battery technologies up-and-coming, are lead-acids still the same
old boring story?

I'll add one note I didn't see posted to sci.electronics.design,
yet. Many years ago, there was an article about lead-acid
battery charging for motorcycle and car batteries. In it, the
author spent a lot of time talking about closely watching the
charging process and observing the little bubbles forming on the
electrodes and that these bubbles stay small enough long enough
to interfere with the plating back process for the lead. He
claimed that this cycle, repeated over and over, yields filar
structures, excessive surface area, possible bridging (if
something else isn't there to prevent it), and operation quite
different from design parameters, eventually.

So, the author designed a circuit which provided a hard charging
current interrupted periodically with a sharp reverse to "knock"
the bubbles off the sides. Then forward current again. Like
that.

Made sense to me and so I built it and tried it. Worked okay.
I also saw just what he'd said I see, the little bubbles forming
and slowly getting larger and eventually rising on their own,
without the "bump circuit" operating. And tiny bubbles barely
getting the chance to form and suddenly knocked off and gently
rising up to the surface every few seconds with the reversing
circuit engaged.

Jon

 

[Dave Platt]

In article <ecp0ivo5h3fn92mj8e0s63qe296hgkru4a@4ax.com>,
Jonathan Kirwan <jkirwan@easystreet.com> wrote:

So, the author designed a circuit which provided a hard charging
current interrupted periodically with a sharp reverse to "knock"
the bubbles off the sides. Then forward current again. Like
that.

Made sense to me and so I built it and tried it. Worked okay.
I also saw just what he'd said I see, the little bubbles forming
and slowly getting larger and eventually rising on their own,
without the "bump circuit" operating. And tiny bubbles barely
getting the chance to form and suddenly knocked off and gently
rising up to the surface every few seconds with the reversing
circuit engaged.

A similar sort of "burp" charging has been recommended for NiCd
batteries as well, for similar reasons.

Another option along these lines is the a charger with a high-voltage
pulse generator - one which creates an inductively-generated voltage
spike periodically. These seem to be popular as "desulphators" - the
high voltage can reportedly break up the normally-insoluble crystals
of lead sulphate which form on the plates. From what I've seen of the
pulse-generation circuits, its waveform almost certainly goes negative
briefly, and might serve to knock off the gas bubbles as well as break
up the sulphate crystals.

--
Dave Platt <dplatt@radagast.org> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

 

[Michael A. Terrell]

Duncan Walters wrote:

I am looking for a source of the MSM5525RS chip.
This is a frequency counter and display driver housed in a 40-pin DIL
package manufactured by OKI.
They ceased making these in the early 1990's.
I wonder if anyone can help?
Do you have one of these gathering dust in your boxes
of chips?
It is needed to replace a faulty one fitted in a shortwave receiver digital
display board.
I have searched the web to no avail, apart from coming up with semiconductor
brokers who only deal with big
companies (not individuals) and who demand a huge minimum order fee.
Any assistance will be greatly appreciated.

Duncan

Ask the brokers for names of companies they have sold the parts to.
Maybe one of them can sell you a single chip.
--


Michael A. Terrell
Central Florida

 

[Peter Gottlieb]

"Tim Shoppa" <shoppa@trailing-edge.com> wrote in message
news:bec993c8.0307240527.5ce2685c@posting.google.com...

The "smart" battery packs have chips that seem to not
only sense cell temperature but have other characteristics (accumulated
charge/discharge, etc.)

I have a patent on perhaps the first of these, and it goes back a while. I
had a micro which read voltage and current going into a battery pack of
lead-acid batteries. The way it worked was to wait for the voltage to get
high enough and the charge current small enough and then it considered the
battery charged. Then when the pack is discharged the micro integrates
current to determine state of charge. As the pack discharges (there may be
many in parallel) certain voltage "checkpoints" are reached and the micro
then looks at how many amp-hours the pack contributed to get to that voltage
and makes a determination as to whether or not the pack is good (i.e.,
meeting a certain minimum number of AH). An eeprom stores parameters such
as count of charge/discharge cycles and the pack capacity as of last
discharge so that the percent of charge remaining at the next discharge may
be determined. This was a number of years back when I originally filed the
patent (more than 10, maybe 15, I'd have to go look) and at that time the
recommended charge method was simple constant voltage float and we were
seeing battery lifetimes which the manufacturers said were all we could
expect to achieve.

Peter

 

[Tim Shoppa]

William P.N. Smith <wpns@compusmiths.com> wrote in message news:<fsj0ivsemhu001dlbom58d9cvqdba1dn6d@4ax.com>...

They call them three-stage:

Constant current to a specific voltage (say 14.4V)
Constant voltage at that voltage till current drops below some
setpoint (say 200 mA)
Constant voltage float at a lower setpoint (say 13.8V).

Note that the first two "stages" are just a current limited power
supply.

I've seen others recommend something similar to the first stage, but
they then apply that higher voltage once a week or so during float to
"equalize" charge. I'm not sure exactly what's unequal that requires
this... I do realize that not all cells will be identical but I'm not
sure how these differences are overcome by overcharging, as all the
currents in the series string are guaranteed to be identical.

And if at all possible I'd like to see these recommendations rise from
"old wives tales" to actual documentation by the battery makers. (As
opposed to sales hype by the charger makers!)

Tim.

 

[Pat Ford]

"Tim Shoppa" <shoppa@trailing-edge.com> wrote in message
news:bec993c8.0307250353.74c40c15@posting.google.com...

William P.N. Smith <wpns@compusmiths.com> wrote in message
news:<fsj0ivsemhu001dlbom58d9cvqdba1dn6d@4ax.com>...
They call them three-stage:

Constant current to a specific voltage (say 14.4V)
Constant voltage at that voltage till current drops below some
setpoint (say 200 mA)
Constant voltage float at a lower setpoint (say 13.8V).

Note that the first two "stages" are just a current limited power
supply.

I've seen others recommend something similar to the first stage, but
they then apply that higher voltage once a week or so during float to
"equalize" charge. I'm not sure exactly what's unequal that requires
this... I do realize that not all cells will be identical but I'm not
sure how these differences are overcome by overcharging, as all the
currents in the series string are guaranteed to be identical.

And if at all possible I'd like to see these recommendations rise from
"old wives tales" to actual documentation by the battery makers. (As
opposed to sales hype by the charger makers!)

Tim.

speaking of lead acid battery old wives tales, the tale about not leaving a
lead acid battery on concrete, fact or fiction??
Pat

 

[Glenn Ashmore]

You are talking about equalization. As a lead acid battery cycles
through charge and discharge lead sulfates build up on the plates. In
regular use a deep cycle battery should be put under higher than normal
charge voltage for a few hours to remove that sulphate and prolong
maximum capacity. It is not a weekly procedure however. Usually it is
monthly or so.

Most high quality marine chargers and 3 stage regulators have an
equalization mode.

Tim Shoppa wrote:

I've seen others recommend something similar to the first stage, but
they then apply that higher voltage once a week or so during float to
"equalize" charge. I'm not sure exactly what's unequal that requires
this... I do realize that not all cells will be identical but I'm not
sure how these differences are overcome by overcharging, as all the
currents in the series string are guaranteed to be identical.

And if at all possible I'd like to see these recommendations rise from
"old wives tales" to actual documentation by the battery makers. (As
opposed to sales hype by the charger makers!)

Tim.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

 

[Dave VanHorn]

speaking of lead acid battery old wives tales, the tale about not leaving
a
lead acid battery on concrete, fact or fiction??
Pat

Ancient fact, no longer true.

http://uuhome.de/william.darden/carfaq14.htm

 

[gene ohara]

Should have asked for good/bad recommendations concerning "emitter resistors"

Thanks

Gene


genosmm@yahoo.com (gene ohara) wrote in message news:<9361bb67.0307241227.73d68ecb@posting.google.com>...

Appreciate any recommentations concerning long term stability of
various output resistors? Both Good and Bad.

Thanks

Gene

 

[Bob Adkins]

On Fri, 25 Jul 2003 09:36:05 -0400, Glenn Ashmore <rutu@bellsouth.net>
wrote:

You are talking about equalization. As a lead acid battery cycles
through charge and discharge lead sulfates build up on the plates. In
regular use a deep cycle battery should be put under higher than normal
charge voltage for a few hours to remove that sulphate and prolong
maximum capacity. It is not a weekly procedure however. Usually it is
monthly or so.

Argh! That's hard to do with a little solar panel and controller. :-(

Bob

 

*** post for FREE via your newsreader at post.newsfeed.com ***


Strixner & Holzinger in Munich list up to 100 pieces of MSM5525RS
made by OKI. They serve private individuals, the minimum order without
fee is 25 Euro (plus 15 Euro for oversees shipping). You can download
their 300kB stocklist and ask for prices using an on-line form.

You should also try Dialelec in Great Britain. Their conditions and
prices are similar; but they may be easier to deal with if you are based
in the US.

In the US, to my knowledge, American Microsemiconductor (AMS) do serve
private customers.

Martin.


Duncan Walters wrote:

I am looking for a source of the MSM5525RS chip.
This is a frequency counter and display driver housed in a 40-pin DIL
package manufactured by OKI.
They ceased making these in the early 1990's.
I wonder if anyone can help?
Do you have one of these gathering dust in your boxes
of chips?
It is needed to replace a faulty one fitted in a shortwave receiver digital
display board.
I have searched the web to no avail, apart from coming up with semiconductor
brokers who only deal with big
companies (not individuals) and who demand a huge minimum order fee.
Any assistance will be greatly appreciated.

Duncan

-----= Posted via Newsfeed.Com, Uncensored Usenet News =-----
http://www.newsfeed.com - The #1 Newsgroup Service in the World!
-----== 100,000 Groups! - 19 Servers! - Unlimited Download! =-----

 

[Fred Abse]

On Wed, 23 Jul 2003 23:16:55 +0100, Robert Monsen wrote:

one of the 100uf
capacitors exploded right in front of me. I've never seen that before!

You must be one of the newer fellas

When I was (much) younger, I and a few of the guys used to amuse
ourselves with a piece of pipe closed at one end, a few electrolytic
capacitors, and the AC supply. We called it the "Cap Gun"

--
Then there's duct tape ...
(Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx

 

[Lewin A.R.W. Edwards]

Strixner & Holzinger in Munich list up to 100 pieces of MSM5525RS

"Verehrte Kunden ! Bitte haben Sie Verständnis dafür, dass die
Bereiche nicht mehr zugänglich sind."