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'[OT] Just had to relate this..'
1999\07\05@145656 by ShadeDemon

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 I was junking a dictaphone transcriber thing (a
secretarial pool kind of device, must have been 5K when new,
around 92 or so, but now they just use PC's) that I got for
$10 from the local university surplus.  I picked it up
because it had a nice 4x40 backlit LCD display built in and
it came up and worked..  It was incredibly overbuilt, small
tight tech for the time, with passive backplane and XT hard
drive controller and 3.5" hard drive to store the voice on.
The backplane had some nice caps etc, but was about to throw
it away when I noticed that the three nice black filter caps
with gold lettering said "gold cap" on them.  Sure enough,
those numbers really said 2.3v 10F, big F, no pesky little u
in there!  Charged it up to 1.93v and put a superbright red
led and 1K resistor on it, and it's still glowing well four
hours later.
 I can't wait to see how long I can get them to run a PIC
doing some low power data sampling.  Definitely an
alternative to batteries for some low power apps, about 1/2"
shorter and 1/8" less diameter than an AA cell.  A bit
pricey, $7.50ea from DigiKey in singles, but not as bad as I
was expecting, and drops to around $3 each at 1K, probably
less from some other distributors.  And the current version
is rated 2.5v, so you only need two to start out with 10F at
5v.  I'm only 30, but I remember how they used to say it'd
take a railroad car size to have a 1F cap not so very long
ago, much less 10F.  Neat to have a small train's worth of
cap powering your PIC..

1999\07\05@165823 by Kevin

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Back around the same time (92) I used one of these in a product. Worked
great as a short term battery backup. When I lost power, I would use one
of those to maintain it for a specified time period (I think it was
about 8 hours max). It's been awhile, but a cautionary word - make sure
the discharge curve fits your intended application. Having it work, and
work reliably can often times be two seperate issues.

Cheers,

Kevin

Alan King wrote:
{Quote hidden}

1999\07\06@020135 by Gaston Gagnon

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I heard the term "SUPER-CAP" once is that it?

Alan King a icrit :
{Quote hidden}

1999\07\07@135102 by Gaston Gagnon

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Is this what is sometime called a "SUPER CAP" ?

<..>
> 5v.  I'm only 30, but I remember how they used to say it'd
> take a railroad car size to have a 1F cap not so very long
> ago, much less 10F.  Neat to have a small train's worth of
> cap powering your PIC..

Oups! I think I owe some apology to someone ;-)
I did not think so much capacity could be enclosed in so small a format
either.

Gaston

1999\07\07@141004 by Dave VanHorn

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> > 5v.  I'm only 30, but I remember how they used to say it'd
> > take a railroad car size to have a 1F cap not so very long
> > ago, much less 10F.  Neat to have a small train's worth of
> > cap powering your PIC..


I guess it's old tech now, but I've got a 2.2F cap that looks exactly like a
lithium coin cell. About the size of a nickle.

1999\07\07@141627 by Wagner Lipnharski

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Yeah, well, a little lithium coin cell is also a kind of capacitor...
and it should be several Farads of equivalence... :)
Wagner.

Dave VanHorn wrote:
>
> > > 5v.  I'm only 30, but I remember how they used to say it'd
> > > take a railroad car size to have a 1F cap not so very long
> > > ago, much less 10F.  Neat to have a small train's worth of
> > > cap powering your PIC..
>
> I guess it's old tech now, but I've got a 2.2F cap that looks exactly like a
> lithium coin cell. About the size of a nickle.

1999\07\07@142248 by Dave VanHorn
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> Yeah, well, a little lithium coin cell is also a kind of capacitor...
> and it should be several Farads of equivalence... :)
> Wagner.

> > I guess it's old tech now, but I've got a 2.2F cap that looks exactly
like a
> > lithium coin cell. About the size of a nickle.

No, I mean a real supercap, fabricated in a battery sized case.

1999\07\07@165531 by Walter Banks

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----------
> From: Dave VanHorn <spam_OUTdvanhornTakeThisOuTspamCEDAR.NET>
> > Yeah, well, a little lithium coin cell is also a kind of capacitor...
> > and it should be several Farads of equivalence... :)
> > Wagner.
>
> > > I guess it's old tech now, but I've got a 2.2F cap that looks exactly
> like a
> > > lithium coin cell. About the size of a nickle.
>
> No, I mean a real supercap, fabricated in a battery sized case.

One amp of current into a 1 farad cap will yield a voltage rise of
1 volt per second. ( amp = coulomb / sec )


A 2.2F cap charged to 1.5 volts has 3.3 Coulomb's stored in it.
Voltage will drop linearily with current draw, Pick a point where
the voltage is no longer useful say 1.0 volts then you can draw
1.1 amps for one second more conventionally 18.3 milliamp hour.

Walter Banks

1999\07\07@183719 by paulb

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face
Dave VanHorn wrote:

> No, I mean a real supercap, fabricated in a battery sized case.

 He probably wasn't questioning that it was.  Since the technology
AFAIK is a variant of conventional electrolytic capacitor manufacture
which uses rolled-up foil, the alternative of using the foil as punched-
out discs and stacking (instead of rolling) these into such a case,
sounds quite straightforward.

 The only problem I could see is making the connections to the layers.
--
 Cheers,
       Paul B.

1999\07\07@211344 by Mark Willis

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Paul B. Webster VK2BZC wrote:
>
> Dave VanHorn wrote:
>
> > No, I mean a real supercap, fabricated in a battery sized case.
>
>   He probably wasn't questioning that it was.  Since the technology
> AFAIK is a variant of conventional electrolytic capacitor manufacture
> which uses rolled-up foil, the alternative of using the foil as punched-
> out discs and stacking (instead of rolling) these into such a case,
> sounds quite straightforward.
>
>   The only problem I could see is making the connections to the layers.
> --
>   Cheers,
>         Paul B.

 I'd try using sort of "Lollipop" shaped electrodes, with "-"
electrodes all on the left & "+" electrodes all on the right, have the
insulators between layers keep the leads from shorting to the case, and
then have an insulator on top & on bottom of the stack - just stick all
the layers of electrode together, all "+" ones on the 'bottom', the rest
on the 'top', with the insulators compressing to make things fit, should
do just fine.

 But, I don't claim to be a supercap expert <G>  Just that I have a
deviously creative mind.

 Mark

1999\07\07@221706 by Sean Breheny

face picon face
I seem to remember a discussion a while back on the very subject of how
they make > 1F caps, and that they were not made like regular
electrolytics. Instead, they had granular carbon or another material with
TONS of surface area as one of the electrodes. Then, something (like a
liquid? I can't really remember) formed the other electrode or the
dielectric. In fact, this was given as a reason why they have really high
ESR (compared to regular electrolytics, whose ESR usualyl goes DOWN as
capacitance goes up).

Sean

At 06:12 PM 7/7/99 -0700, you wrote:
{Quote hidden}

| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
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1999\07\07@223145 by Sean Breheny

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I think that the ultimate limiting factor for the energy stored in a
capacitor is the dielectric strength. One way to think of the energy stored
in a cap is to think of the electric field. IIRC, the electric field
strength cubed times the volume it is contained in,times some constant,
gives an estimate of the enegry stored. So, if you know the dielectric
material's breakdown field, then you can place an upper limit on the stored
energy. It is kinda humbling to see how even a SUPERCAP pales in comparison
to a weak little button cell.

This is also a reason why batteries have much higher energy densities than
caps. In a battery, there is no requirement for a high electric field
permeating the storage volume. The energy ultimately comes from the
potential energy of the chemical bonds. An electric field is still involved
at the molecular level, but the "dielectric" is provided not by matter, not
even by a vacuum,but instead by the allowed states of the electrons,as
dictated by quantum mech.

The upper limit then becomes the electronegativity difference between the
elements involved (how strong the reaction between them is). I'd still like
to see a Francium-Floride cell <VBEG>

The next step beyond this,of course,is to harness the nuclear strong force,
and its potential energy. Anyone ever seen nuclear batteries? I have seen
pictures, but never one in person. The theory behind the ones I've seen was
using a target to absorb the particles emitted by the source,which turns
the energy into heat,which is used by thermocouples.

Sean


At 04:45 PM 7/7/99 -0400, you wrote:
{Quote hidden}

| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
shb7spamKILLspamcornell.edu ICQ #: 3329174
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1999\07\07@224841 by Dave VanHorn

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> The next step beyond this,of course,is to harness the nuclear strong
force,
> and its potential energy. Anyone ever seen nuclear batteries? I have seen
> pictures, but never one in person. The theory behind the ones I've seen
was
> using a target to absorb the particles emitted by the source,which turns
> the energy into heat,which is used by thermocouples.


There's another route, use an alpha emitter, and a metal target that catches
the alpha particles. Vaccum between. Just how high a voltage did you want?

1999\07\08@010611 by Sean Breheny

face picon face
Thanks for the reply,but I'm not actually "in the market" for these, I was
just curious. That is an interesting method you suggested, though. I forget
what the usual energy of alpha particles is. Why not use Beta particles?
Don't they usually have higher kinetic energy?

Sean

At 09:44 PM 7/7/99 -0500, you wrote:
>
>
>There's another route, use an alpha emitter, and a metal target that catches
>the alpha particles. Vaccum between. Just how high a voltage did you want?
>
|
| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
.....shb7KILLspamspam.....cornell.edu ICQ #: 3329174
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1999\07\08@010622 by Sean Breheny

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I just realized I have a little correction/addendum to make to my own
comments, here. I think technically, nuclear batteries use the nuclear WEAK
force, not the strong. Strong holds nuclei together. IIRC, the weak is
responsible for decay.

Sean

At 09:44 PM 7/7/99 -0500, you wrote:
{Quote hidden}

| Sean Breheny
| Amateur Radio Callsign: KA3YXM
| Electrical Engineering Student
\--------------=----------------
Save lives, please look at http://www.all.org
Personal page: http://www.people.cornell.edu/pages/shb7
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1999\07\08@011852 by Dave VanHorn

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> Thanks for the reply,but I'm not actually "in the market" for these, I was
> just curious. That is an interesting method you suggested, though. I
forget
> what the usual energy of alpha particles is. Why not use Beta particles?
> Don't they usually have higher kinetic energy?

I suppose you could, I don't know if there's any long term effects from beta
bombardment, but alpha's pretty benign. IIRC batteries of this type powered
pacemakers. (maybe still, I'm not in the med field.)  You wouldnt' want to
EAT an alpha emitter, but as long as it's outside you, you're superman, able
to stop a speeding alpha particle with your bare hand. :)

1999\07\08@063932 by Caisson

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> Van: Gaston Gagnon <gagnongspamspam_OUTTOTAL.NET>
> Aan: @spam@PICLISTKILLspamspamMITVMA.MIT.EDU
> Onderwerp: Re: [OT] Just had to relate this..
> Datum: woensdag 7 juli 1999 20:57
>
> > 5v.  I'm only 30, but I remember how they used to say it'd
> > take a railroad car size to have a 1F cap not so very long
> > ago, much less 10F.  Neat to have a small train's worth of
> > cap powering your PIC..
>
> Oups! I think I owe some apology to someone ;-)
> I did not think so much capacity could be enclosed in so small a format
> either.

It can't ...  It's not a real Capacitor.  It's more like a small
rechargable battery.  And it has got a rather large internal resistance
(both to charge and de-charge).  So, no good to make sparks with :-)

Greetz,
 Rudy Wieser

1999\07\27@111059 by wwl

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On Thu, 8 Jul 1999 09:48:29 +0200, you wrote:

>> Van: Gaston Gagnon <KILLspamgagnongKILLspamspamTOTAL.NET>
>> Aan: RemoveMEPICLISTTakeThisOuTspamMITVMA.MIT.EDU
>> Onderwerp: Re: [OT] Just had to relate this..
>> Datum: woensdag 7 juli 1999 20:57
>>
>> > 5v.  I'm only 30, but I remember how they used to say it'd
>> > take a railroad car size to have a 1F cap not so very long
>> > ago, much less 10F.  Neat to have a small train's worth of
>> > cap powering your PIC..
>>
>> Oups! I think I owe some apology to someone ;-)
>> I did not think so much capacity could be enclosed in so small a format
>> either.
>
>It can't ...  It's not a real Capacitor.  It's more like a small
>rechargable battery.  And it has got a rather large internal resistance
>(both to charge and de-charge).  So, no good to make sparks with :-)
>
I recently saw ad ad for some caps from Maxwell - I think about the
size of a cigarette packet, a few farads at low voltages, but designed
for high discharge currents (100s or 1000s of amps) - doubt they're
cheap though!

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