Post by thread:Radio Shack, electrolytic caps, polarity, poor lab

I know... I'm dumb. But I gotta know... I just bought a big old 1mF electrolytic cap at Radio Shack to clean up any possible power supply fluctuations in my Scenix SX52 test circuits (since the SX52 is a-ffrrreakeeennn) and opened it to find that the only indication of the polarity is a white band down one side (by the shorter of the two leads) which is broken into arrow like sections by a ">" with a box like shape (trying to be a minus?) in the center of each section. There is no + sign, no - sign (unless the box means minus) and I am tired. This must be another one of the many electronics engineers insider only things. Us software/digital logic guys are just S.O.L. The guy at Radio Shack smiled condescendingly and said "the shorter lead is always positive." If he is right I'm going to feel really stupid. So... which lead goes to Vcc and which goes to GND? I ask this question just to show that I can be more annoying than Andy and his Internet Clean-Up. ;) James Newton, webmaster http://get.to/techref spam_OUTjamesnewtonTakeThisOuTgeocities.com 1-619-652-0593 phone

THE LONGER LEAD IS POSITIVE ON ELECTROLYTICS..........<G>..............RADIO SLACK....... ----- Original Message ----- From: James Newton <.....eplus1KILLspam@spam@san.rr.com> To: <PICLISTKILLspamMITVMA.MIT.EDU> Sent: Wednesday, July 07, 1999 1:25 PM Subject: Radio Shack, electrolytic caps, polarity, poor label, dumb tech > I know... I'm dumb. But I gotta know... > > I just bought a big old 1mF electrolytic cap at Radio Shack to clean up any > possible power supply fluctuations in my Scenix SX52 test circuits (since > the SX52 is a-ffrrreakeeennn) and opened it to find that the only indication > of the polarity is a white band down one side (by the shorter of the two > leads) which is broken into arrow like sections by a ">" with a box like > shape (trying to be a minus?) in the center of each section. There is no + > sign, no - sign (unless the box means minus) and I am tired. This must be > another one of the many electronics engineers insider only things. Us > software/digital logic guys are just S.O.L. > > The guy at Radio Shack smiled condescendingly and said "the shorter lead is {Quote hidden}> always positive." If he is right I'm going to feel really stupid. > > So... which lead goes to Vcc and which goes to GND? > > I ask this question just to show that I can be more annoying than Andy and > his Internet Clean-Up. ;) > > James Newton, webmaster http://get.to/techref > .....jamesnewtonKILLspam.....geocities.com 1-619-652-0593 phone >

On Wed, Jul 07, 1999 at 01:25:22PM -0700, James Newton wrote: > leads) which is broken into arrow like sections by a ">" with a box like > shape (trying to be a minus?) in the center of each section. There is no + this is indeed a minus sign. The short lead is negative. Just like LEDs. The anode is the long lead. Valves (vacuum toobs for the Yanks) were easy, the anode was the cap on top. In days of yore, electros always had a plus sign on the positive lead. Some many years ago I noticed that they now had the negative lead indicated by minus signs, and nothing on the positive lead. I have no idea why the convention changed, but it did. Axial lead electros also used to have (still do AFAIK) an indented ring at the positive end, but that doesn't help much with single ended ones :-) > The guy at Radio Shack smiled condescendingly and said "the shorter lead is > always positive." If he is right I'm going to feel really stupid. Ask him if they'll replace it if they're wrong :-) Cheers, Clyde -- Clyde Smith-Stubbs | HI-TECH Software Email: EraseMEclydespam_OUTTakeThisOuThtsoft.com | Phone Fax WWW: http://www.htsoft.com/ | USA: (408) 490 2885 (408) 490 2885 PGP: finger clydespam_OUThtsoft.com | AUS: +61 7 3355 8333 +61 7 3355 8334 --------------------------------------------------------------------------- HI-TECH C: compiling the real world.

At 13:31 8/07/99 +1000, you wrote: >On Wed, Jul 07, 1999 at 01:25:22PM -0700, James Newton wrote: >> leads) which is broken into arrow like sections by a ">" with a box like >> shape (trying to be a minus?) in the center of each section. There is no + > >this is indeed a minus sign. The short lead is negative. Just like LEDs. The >anode is the long lead. Valves (vacuum toobs for the Yanks) were easy, >the anode was the cap on top. > >In days of yore, electros always had a plus sign on the positive lead. Some >many years ago I noticed that they now had the negative lead indicated by minus >signs, and nothing on the positive lead. I have no idea why the convention >changed, but it did. Labling reasons, just like why active becomes brown and neutral blue, no printing error or slight rubbing off can make a -ve look like a +ve where a +ve can look like a -ve. Hard to come to grips with, but seems reasonable. By the the way what is a toob? I know what a chewb, a tube and a chube is :) Dennis

On Thu, Jul 08, 1999 at 02:38:45PM +1000, Dennis Plunkett wrote: > By the the way what is a toob? I know what a chewb, a tube and a chube is :) American for tube. Americans (especially Californians) make do with only about 3 vowel sounds. -- Clyde Smith-Stubbs | HI-TECH Software Email: @spam@clydeKILLspamhtsoft.com | Phone Fax WWW: http://www.htsoft.com/ | USA: (408) 490 2885 (408) 490 2885 PGP: finger KILLspamclydeKILLspamhtsoft.com | AUS: +61 7 3355 8333 +61 7 3355 8334 --------------------------------------------------------------------------- HI-TECH C: compiling the real world.

At 09:28 PM 7/8/99 +1000, you wrote: >On Thu, Jul 08, 1999 at 02:38:45PM +1000, Dennis Plunkett wrote: > >> By the the way what is a toob? I know what a chewb, a tube and a chube is :) > >American for tube. Americans (especially Californians) make do with only >about 3 vowel sounds. In New York City and Boston they discard various consonants, or they replace them with new vowel sounds. In the South they discard certain harder consonants. Like sentence becomes "senence," Saturday becomes "Saurdee" (still three syllables). At least we don't have weird accents like those aussies and sheep-chasing new zealanders. <G> Andy ================================================================== Andy Kunz Life is what we do to prepare for Eternity ------------------------------------------------------------------ RemoveMEandyTakeThisOuTrc-hydros.com http://www.rc-hydros.com - Race Boats spamBeGoneandyspamBeGonemontanadesign.com http://www.montanadesign.com - Electronics ==================================================================

... by the rule of the thumb (rule of stripe here), white band is positive side and long lead is to ground... for sure... except if it is reversed... :)... confused?... me too. Wagner. Matt Bonner wrote: {Quote hidden}> > James Newton wrote: > > > > I just bought a big old 1mF electrolytic cap ... and opened > > it to find that the only indication > > of the polarity is a white band down one side (by the shorter of the two > > leads) > > > So... which lead goes to Vcc and which goes to GND? > > > The white band indicates the positive side, ergo: short lead to Vcc and > longer lead to Gnd. > > --Matt

Clyde said: >signs, and nothing on the positive lead. I have no idea why the convention >changed, but it did. I noticed that, too. Seems like it wasn't that long ago; a decade or so. Somebody, somewhere must know the reason for the change. Any capacitor industry insiders on this list? > >Axial lead electros also used to have (still do AFAIK) an indented ring >at the positive end, but that doesn't help much with single ended ones :-) On aluminum electrolytics, the crimp holds the seal in place. It's not explicitly for indicating polarity, but the can is the negative terminal so for axial caps the open end where the positive lead emerges is always the crimped end. For radial caps the can may not be part of the circuit at all; I don't know why this is. Reg Neale

This is not always true. Gabriel -----Original Message----- From: Lynx {Glenn Jones} <TakeThisOuTjones_glEraseMEspam_OUTEFN.ORG> To: RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU <PICLISTEraseME.....MITVMA.MIT.EDU> Date: Thursday, July 08, 1999 3:10 PM Subject: Re: Radio Shack, electrolytic caps, polarity, poor label, dumb tech {Quote hidden}>for LED's I always check which lead is connected to the metal cup, cause >thats always the cathode. > >On Wed, 7 Jul 1999, Roland Andrag wrote: > >> The short lead is the NEGATIVE. And that box like arrow shape thing is >> trying to be a minus. This goes for LED's as well - short lead negative. >> >> Cheers >> Roland >> -----Original Message----- >> From: James Newton <EraseMEeplus1san.rr.com> >> To: RemoveMEPICLISTEraseMEEraseMEMITVMA.MIT.EDU <RemoveMEPICLISTspam_OUTKILLspamMITVMA.MIT.EDU> >> Date: 07 July 1999 23:08 >> Subject: Radio Shack, electrolytic caps, polarity, poor label, dumb tech >> >> >> >I know... I'm dumb. But I gotta know... >> > >> >I just bought a big old 1mF electrolytic cap at Radio Shack to clean up any >> >possible power supply fluctuations in my Scenix SX52 test circuits (since >> >the SX52 is a-ffrrreakeeennn) and opened it to find that the only >> indication >> >of the polarity is a white band down one side (by the shorter of the two >> >leads) which is broken into arrow like sections by a ">" with a box like >> >shape (trying to be a minus?) in the center of each section. There is no + >> >sign, no - sign (unless the box means minus) and I am tired. This must be >> >another one of the many electronics engineers insider only things. Us >> >software/digital logic guys are just S.O.L. >> > >> >The guy at Radio Shack smiled condescendingly and said "the shorter lead is >> >always positive." If he is right I'm going to feel really stupid. >> > >> >So... which lead goes to Vcc and which goes to GND? >> > >> >I ask this question just to show that I can be more annoying than Andy and >> >his Internet Clean-Up. ;) >> > >> >James Newton, webmaster http://get.to/techref >> >RemoveMEjamesnewtonTakeThisOuTspamgeocities.com 1-619-652-0593 phone >> > >>

>>> >I ask this question just to show that I can be more annoying than Andy and >>> >his Internet Clean-Up. ;) I would just like to get more bandwidth. The SYSOPS on this and other lists have enjoyed the posting. Not the zillions of replies, but the concept. Andy ================================================================== Andy Kunz Life is what we do to prepare for Eternity ------------------------------------------------------------------ EraseMEandyspamspamBeGonerc-hydros.com http://www.rc-hydros.com - Race Boats RemoveMEandyKILLspammontanadesign.com http://www.montanadesign.com - Electronics ==================================================================

Lynx {Glenn Jones} wrote: > for LED's I always check which lead is connected to the metal cup, > cause thats always the cathode. *BONG!!* Missed out on that one! Next contestant please. That used to be true of the "super-dim" LED technology 20 years ago. Whilst not universally true, the current "efficient" LED technology uses a process whereby the light emanates from the other side of the die (I'm no expert by any means) and the "header" is the positive lead. Reginald Neale wrote: > the can is the negative terminal so for axial caps the open end where > the positive lead emerges is always the crimped end. For radial caps > the can may not be part of the circuit at all; I don't know why this > is. I can give a clue here. The process of oxide formation on the foil is called "anodizing", i.e., it occurs on the positive electrode. This process is applied to the foil but of course cannot be performed on the casing, so the casing must either be isolated, or the cathode. -- Cheers, Paul B.

Lynx {Glenn Jones} wrote: > for LED's I always check which lead is connected to the metal cup, > cause thats always the cathode. "Paul B. Webster VK2BZC" wrote: > *BONG!!* Missed out on that one! Next contestant please. Some LED's don't even have a flat surface on the cathode side of the plastic moulding either. Testing the thing is probably the safest way to go, if you are a low end user like me. It can be frustrating when that little LED does not light when it's supposed to, especially when you expect the worst from your new design :-) -- Best regards Tony 'The Engine' - Design your own programmer. http://www.picnpoke.com Email picnpokeSTOPspamspam_OUTcdi.com.au

On Thu, 8 Jul 1999 13:08:29 -0700 Lynx {Glenn Jones} <spamBeGonejones_glSTOPspamEraseMEEFN.ORG> writes: >for LED's I always check which lead is connected to the metal cup, >cause >thats always the cathode. Most infrared and superbright LEDs are exactly the opposite. Looking at the internal parts is not a good way to tell. The standard marking method is based on making the lower flange of the LED's plastic shell not quite round. There is a flat spot next to the cathode lead. Also the cathode lead is shorter than the anode lead, of course that works only for new LEDs. ___________________________________________________________________ Get the Internet just the way you want it. Free software, free e-mail, and free Internet access for a month! Try Juno Web: dl.http://www.juno.com/dynoget/tagj.

>At least we don't have weird accents like those aussies and sheep-chasing >new zealanders. <G> > >Andy That should be "New Zealanders", please. Note that we are good at what we are good at - 1. All English is migrating towards being spoken as she is spoken here (even genuine Brit version, to their horror). 2. The mighty US of A is so scared of our free market unsubsidised sheep farming efficiencies that they have slapped a 9% import tax (called something else) on our lamb imports to protect the poor inefficient uncompetitive US sheep farming industry - sounds like sheep-belly politics to me :-). 3. TO KEEP THIS ON TOPIC :-) A nice trick for checking electro cap (metal can version only) polarity in circuit that I have not seen mentioned elsewhere (I should post this separately perhaps?) - Ground negative meter probe - Operate circuit - Measure voltage on can of working electrolytics. Properly polarised caps will typically show a voltage of from about 0.1 to 0.5 volts. Reverse biased caps will have a can potential much closer to supply. ie the can is not at but is NEAR the potential of the true negative terminal. For a reversed cap in the 10uF - 1000uF range on a 5 volt supply the can is typically at 2 or 3 volts but anything over about 0.5 is suspect. regards Russell McMahon >================================================================== >Andy Kunz Life is what we do to prepare for Eternity >------------------------------------------------------------------ >KILLspamandyspamBeGonerc-hydros.com http://www.rc-hydros.com - Race Boats >EraseMEandyEraseMEmontanadesign.com http://www.montanadesign.com - Electronics >================================================================== >

Well my experience with identifying Electrolytic capacitors be they conventional or Tantalum is that if you see two negative looking bars on both sides start worrying! Sure, Manufacturers seems to take pride in doing their own thing, but if I found a cap with nothing on one side, and a stipe on the other, given that the East decided to change the standard colour code of mains wiring from RED/BLACK/GREEN to BLUE/BROWN/GREEN, I would assume the stripe meant POSITIVE. Can you see the logic in that? As Russell said, use a meter and measure the cap. Its easy to tell the polarity this way. And to wander off topic, this sheep import tax scenario sounds like a payback for Aussie giving the US of A a hard time over the Olympics and Marching Bands to me? Could this be so? Cheers .. Bob > {Original Message removed}

Mike said: >Most infrared and superbright LEDs are exactly the opposite. Looking at >the internal parts is not a good way to tell. The standard marking >method is based on making the lower flange of the LED's plastic shell not >quite round. There is a flat spot next to the cathode lead. Also the >cathode lead is shorter than the anode lead, of course that works only >for new LEDs. > The convention of identifying T1 and T1 3/4 LED cathodes with a flat is the closest thing to universal that I've ever seen. Has anyone ever seen an exception? Reg Neale

>1. All English is migrating towards being spoken as she is spoken >here (even genuine Brit version, to their horror). And as soon as I can figure out how to get Adobe to make a font with :-) and all the others as single characters, I'll be set! >sheep farming efficiencies that they have slapped a 9% import tax The farm coalition in the US is one of the most powerful lobbying segments. Other powerful ones are NRA (National Rifle Association, to protect our Constitutional rights) and the NEA (National Education Association, to protect their jobs). The NEA is so powerful that it is the only union which has an official government department, and it was very openly created as paybacks to the NEA for support of a particular candidate for President. >3. TO KEEP THIS ON TOPIC :-) >A nice trick for checking electro cap (metal can version only) I was looking for a trick, like "charge cap, hand to newbie tech to see reaction as he closed the leads" or such. Andy ================================================================== Andy Kunz Life is what we do to prepare for Eternity ------------------------------------------------------------------ @spam@andy@spam@spam_OUTrc-hydros.com http://www.rc-hydros.com - Race Boats spamBeGoneandyKILLspammontanadesign.com http://www.montanadesign.com - Electronics ==================================================================

<big snip> >> >The white band indicates the positive side, ergo: short lead to Vcc and >longer lead to Gnd. Sorry, but I must disagree here. The identified lead on all aluminum electrolytic caps *I* have seen in the past 25 years or so is NEGATIVE. Do NOT use lead length as your polarity marking. Tantalum capacitors, OTOH, usually mark the POSITIVE lead. Don't ask me why. dwayne Dwayne Reid <.....dwaynerspam_OUTplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 15 years of Engineering Innovation (1984 - 1999) * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Do NOT send unsolicited commercial email to this email address. My posting messages to Usenet neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email.

easy: Tantalum use longer lead as positive because: from Sumitswu language, talked on Aural Islands at Muriatic Ocean: Tan = Positive Action, Right Thing, Goood Polarity, Right Side, Stay at the Correct group, etc... Talum = Long, Tall, High, Strong, Durable, etc. So, Tan+Talum, means Longer Lead is the Positive one. Easy hum? :) Wagner. Dwayne Reid wrote: {Quote hidden}> > <big snip> > >> > >The white band indicates the positive side, ergo: short lead to Vcc and > >longer lead to Gnd. > > Sorry, but I must disagree here. The identified lead on all aluminum > electrolytic caps *I* have seen in the past 25 years or so is NEGATIVE. Do > NOT use lead length as your polarity marking. > > Tantalum capacitors, OTOH, usually mark the POSITIVE lead. Don't ask me why. > > dwayne > > Dwayne Reid <TakeThisOuTdwayner.....TakeThisOuTplanet.eon.net> > Trinity Electronics Systems Ltd Edmonton, AB, CANADA > (780) 489-3199 voice (780) 487-6397 fax > > Celebrating 15 years of Engineering Innovation (1984 - 1999) > > * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * > Do NOT send unsolicited commercial email to this email address. > My posting messages to Usenet neither grants consent to receive > unsolicited commercial email nor is intended to solicit commercial > email.

>From all the caps i've seen so far (bout 15 yrs) the white line is always negative, i dun bother with the length of their leads tho... Terry At 11:40 AM 7/8/99 -0400, you wrote: {Quote hidden}>... by the rule of the thumb (rule of stripe here), white band is >positive side and long lead is to ground... for sure... except if it is >reversed... :)... confused?... me too. > >Wagner. > > > > >Matt Bonner wrote: >> >> James Newton wrote: >> > >> > I just bought a big old 1mF electrolytic cap ... and opened >> > it to find that the only indication >> > of the polarity is a white band down one side (by the shorter of the two >> > leads) >> >> > So... which lead goes to Vcc and which goes to GND? >> > >> The white band indicates the positive side, ergo: short lead to Vcc and >> longer lead to Gnd. >> >> --Matt >

Terry wrote: > > >From all the caps i've seen so far (bout 15 yrs) the white line is always > negative, i dun bother with the length of their leads tho... SMD tantalums have the line on the positive side. -- Friendly Regards /"\ \ / Tjaart van der Walt X ASCII RIBBON CAMPAIGN TakeThisOuTtjaartKILLspamspamcellpt.co.za / \ AGAINST HTML MAIL |--------------------------------------------------| | GSM Technology for Positioning and Telematics | | Cellpoint Systems SA http://www.cellpt.com | | http://www.wasp.co.za/~tjaart/index.html | | WGS84 -26.0124 +28.1129 Voice +27 (0)11 2545100 | |--------------------------------------------------|