Post by thread:[OT] Just had to relate this..

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..

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}> > 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..

I heard the term "SUPER-CAP" once is that it? Alan King a icrit : {Quote hidden}> > 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..

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.

---------- > From: Dave VanHorn <spam_OUTdvanhornTakeThisOuTCEDAR.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

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

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}> 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 > | | 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 .....shb7KILLspam@spam@cornell.edu ICQ #: 3329174 ________________________________________________________ NetZero - We believe in a FREE Internet. Shouldn't you? Get your FREE Internet Access and Email at http://www.netzero.net/download/index.html

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}>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 > | | 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 shb7KILLspamcornell.edu ICQ #: 3329174 ________________________________________________________ NetZero - We believe in a FREE Internet. Shouldn't you? Get your FREE Internet Access and Email at http://www.netzero.net/download/index.html

> 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?

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 .....shb7KILLspam.....cornell.edu ICQ #: 3329174 ________________________________________________________ NetZero - We believe in a FREE Internet. Shouldn't you? Get your FREE Internet Access and Email at http://www.netzero.net/download/index.html

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}>> 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? > | | 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 EraseMEshb7spam_OUTTakeThisOuTcornell.edu ICQ #: 3329174 ________________________________________________________ NetZero - We believe in a FREE Internet. Shouldn't you? Get your FREE Internet Access and Email at http://www.netzero.net/download/index.html

> 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. :)

> Van: Gaston Gagnon <gagnongspam_OUTTOTAL.NET> > Aan: @spam@PICLISTKILLspamMITVMA.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

On Thu, 8 Jul 1999 09:48:29 +0200, you wrote: >> Van: Gaston Gagnon <KILLspamgagnongKILLspamTOTAL.NET> >> Aan: RemoveMEPICLISTTakeThisOuTMITVMA.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!