Kenwood L-1000T , 1990

[baron]

Baron Inscribed thus:

Baron Inscribed thus:

David Inscribed thus:

I would concur with William. I have a 0.22F @ 5v on my desk at
the moment, it holds its charge for many days.

Best Regards:
Baron.

Lets get things correct here. Memory backup capacitors can have
very high capacitance values and extremely low leakage. That is
not in dispute. The term supercap does not refer to the typical
memory capacitor installed on consumer electronics equipment.
That is a different type that has high series resistance. If you
have a ESR meter, measure one for yourself but discharge it first
for a long time.

David

Thanks for your note.
Yes the cap I have is intended for memory retention service. I do
have an ESR meter but it hadn't occurred to me to actually measure
it,
though I do take your point about discharging it first. I did
discharge it some time ago and was surprised by how much the voltage
had recovered the following day.


Just and update: I got the marked value wrong, its 2.2F @ 5v. There
is
no indication of the manufacturer. I've currently got a 4.5v 60ma
torch bulb connected across it to discharge it. It took a few seconds
for the bulb to stop glowing. Anyway I'm going to leave it overnight
and check its ESR tomorrow. It should be well and truly discharged by
then.

Following up: The ESR measures 10-11 ohms (last digit can't make up its
mind). Peak charge current from a 5v 0.5ohm source hits 480ma (AVO 8
on 1A range) before rapidly dropping to zero. Four hours later the
terminal voltage is still 5V (Advance 10Mopv meter).

--
Best Regards:
Baron.

 

[baron]

N_Cook Inscribed thus:

Cydrome Leader <presence@MUNGEpanix.com> wrote in message
news:i90gcu$2ra$1@reader1.panix.com...
William Sommerwerck <grizzledgeezer@comcast.net> wrote:
Lets get things correct here. Memory backup capacitors can have
very high capacitance values and extremely low leakage. That is
not in dispute. The term supercap does not refer to the typical
memory capacitor installed on consumer electronics equipment.
That is a different type that has high series resistance. If you
have a ESR meter, measure one for yourself but discharge it first
for a long time.

I'm not sure what the "typical" memory capacitor is. With respect
to my
Lux
5T50, the cap was one I selected and installed.

for something like that from 1990, it would most likely be a cap made
by Elna (quite likely dark blue) NEC (possibly green) or Panasonic
(all sorts of colors). Standard Oil was even making them at the time.

Also, they didn't have 'low' ESR supercaps like they do now, so
ignore any crap off wikipedia or comparisons to modern datasheets for
products that look the same.



I discharged overnight an NEC U6 265 green, 0.2F, 5.5V and got an ESR
of 5.6R

That's about half of the value I measured.

--
Best Regards:
Baron.

 

[David]

"baron" wrote in message
news:i91jrh$810$1@news.eternal-september.org...

Baron Inscribed thus:

Baron Inscribed thus:

David Inscribed thus:

I would concur with William. I have a 0.22F @ 5v on my desk
at
the moment, it holds its charge for many days.

Best Regards:
Baron.

Lets get things correct here. Memory backup capacitors can
have
very high capacitance values and extremely low leakage. That
is
not in dispute. The term supercap does not refer to the
typical
memory capacitor installed on consumer electronics equipment.
That is a different type that has high series resistance. If
you
have a ESR meter, measure one for yourself but discharge it
first
for a long time.

David

Thanks for your note.
Yes the cap I have is intended for memory retention service.
I do
have an ESR meter but it hadn't occurred to me to actually
measure
it,
though I do take your point about discharging it first. I did
discharge it some time ago and was surprised by how much the
voltage
had recovered the following day.


Just and update: I got the marked value wrong, its 2.2F @ 5v.
There
is
no indication of the manufacturer. I've currently got a 4.5v
60ma
torch bulb connected across it to discharge it. It took a few
seconds
for the bulb to stop glowing. Anyway I'm going to leave it
overnight
and check its ESR tomorrow. It should be well and truly
discharged by
then.


Following up: The ESR measures 10-11 ohms (last digit can't
make up its
mnd). Peak charge current from a 5v 0.5ohm source hits 480ma
(AVO 8
on 1A range) before rapidly dropping to zero. Four hours later
the
terminal voltage is still 5V (Advance 10Mopv meter).

--
Best Regards:
Baron.

You have a good one with 10 ohms. The 10 - 15 year old ones had
much higher ESR even when new but still low leakage.

David

 

[baron]

David Inscribed thus:

"baron" wrote in message
news:i91jrh$810$1@news.eternal-september.org...

Baron Inscribed thus:

Baron Inscribed thus:

David Inscribed thus:

I would concur with William. I have a 0.22F @ 5v on my desk
at
the moment, it holds its charge for many days.

Best Regards:
Baron.

Lets get things correct here. Memory backup capacitors can
have
very high capacitance values and extremely low leakage. That
is
not in dispute. The term supercap does not refer to the
typical
memory capacitor installed on consumer electronics equipment.
That is a different type that has high series resistance. If
you
have a ESR meter, measure one for yourself but discharge it
first
for a long time.

David

Thanks for your note.
Yes the cap I have is intended for memory retention service.
I do
have an ESR meter but it hadn't occurred to me to actually
measure
it,
though I do take your point about discharging it first. I did
discharge it some time ago and was surprised by how much the
voltage
had recovered the following day.


Just and update: I got the marked value wrong, its 2.2F @ 5v.
There
is
no indication of the manufacturer. I've currently got a 4.5v
60ma
torch bulb connected across it to discharge it. It took a few
seconds
for the bulb to stop glowing. Anyway I'm going to leave it
overnight
and check its ESR tomorrow. It should be well and truly
discharged by
then.


Following up: The ESR measures 10-11 ohms (last digit can't
make up its
mnd). Peak charge current from a 5v 0.5ohm source hits 480ma
(AVO 8
on 1A range) before rapidly dropping to zero. Four hours later
the
terminal voltage is still 5V (Advance 10Mopv meter).

--
Best Regards:
Baron.

You have a good one with 10 ohms. The 10 - 15 year old ones had
much higher ESR even when new but still low leakage.

David

Wow ! Thanks.
Apart from playing with it yesterday, its sat on my bench for weeks
looking for something to do...

--
Best Regards:
Baron.