Are Your Capacitors Installed Backwards? Build this and find out

If you have been installing, orange dip, brown dip, green dip capacitors over the years, have you been installing them the right way? Even the little yellow ones have polarity in circuit. Find out how to test your capacitors before you install them.... Then build this test fixture to make it even easier.

[@90FF1]

In my 79 years of attending classes, primary, military, and advanced education, I've never had an instructor who presented as well as yourself. Thank you for sharing you time and knowledge.

[@MrCarlsonsLab]

90FF1 Thanks for the nice comment. Glad your enjoying the video's!

[@kenworth176]

I wish I knew what you have forgotten they would call me Mr Einstein or Albert for short I don't know why your head isn't the size of a bowling ball to house your brain thank you so much for being you and the education you put out there for free I know the big guy upstairs is proud of you thanks a million RUCKUSSAY45

[@itme1191]

​@@kenworth176 You probably never heard of Tesla. When Einstein was asked what it was like to be the smartest in the world, he tried to be as honest as possible without snark.

[@GeneralChangFromDanang]

Holy crap, your lab is like a submarine sonar room. I love it.

[@rogerfurer2273]

Wow! I never thought about how the physical construction of a cap would interact with nearby fields. 40 years in electronics engineering and I learned something new from this video! Thank you Mr. Carlson.

[@jamesangelucci5052]

I knew this when I was 12,years old

[@BenState]

40 years and you werent aware of this???????

[@rogerfurer2273]

@@BenState Never came up in analog audio.

[@georgegonzalez2476]

It's only marginally relevant. Paper caps usually are used for their low impedance characteristic. So both foils are at the same AC voltage. So either way is fine. If you're a real purist, just ensure that any plate to chassis capacitor goes in the "right" way or is spaced at least 1/4 inch from any low-level signals. That said, even after 65 years of putting in capacitors willy-nilly I've never seen a radio oscillate or howl due a to "reversed" capacitor. Kudos to anybody that goes that extra distance. Long ago when Heathkits were a thing I would line up all the resistors in the same direction, just to look "right".

[@rusty1187]

I must say, I took electronics in 1980. We started with tube theory and then semiconductors, and your knowledge is light years ahead of any instructors i ever had!!! I'm almost 60 now, and am still learning stuff from you! keep it up!

[@dcolb121]

And yet he mispronounces solder.

[@chrisloh745]

@@dcolb121 RFMAO

[@daleburrell6273]

​@@dcolb121...well, "ya CAN'T please EVERYBODY!!!"

[@normjacques6853]

Hi Mr. Carlson! The U.S. Navy trained me almost fifty years ago (avionics). During that time, and with all of the contact that I have had with engineers and technicians since, nobody else ever pointed out potential polarity issues with non-electrolytic caps!! I stumbled across this video quite by accident, but am so happy (and grateful) that I did! In retirement, the only electronics that I deal with are electric guitars and amplifiers, but you just switched on a bright light...shining on some of the 'mystery noise' issues so common with amplified guitars and basses! Thanks!! As a considerably less 'elegant' alternative to your new bit of test gear, I simply used a DPDT switch, a metal box (shielding, of course), some clear labeling, and physically switch back and forth between 'Normal' to 'Reverse!' I could have added LEDs, a couple of resistors, a battery, and changed to a 4PDT switch, but figured that the O-scope display was plenty! Works fine, was way less expensive, has fewer potential points of failure (like none!), and only took twenty minutes to build! I decided that, at 65, the 'KISS' principle would serve me better! :-) Thanks again....brilliant video!

[@MrCarlsonsLab]

I'm glad you found this useful!

[@Cougar139tweak]

Tweak or Tron God? ( O or I level?)

[@WereReallyRelayCamping]

How can you sit and type that it has zero points of failure when it contains a mechanical switch... Yeah I'm smirking but it's not a hate comment just a smug one.

[@DataWaveTaGo]

@@WereReallyRelayCamping OK, zero failure until 1 million cycles reached (typical switch life). At 10 caps a day tested that's 273 years of service. ;)

[@WereReallyRelayCamping]

@@DataWaveTaGo makes you wonder if switches are so reliable why I get through so many toasters.... Lol just pulling your leg yeah most switches if not $5 for a bag of 100 off eBay should outlive us.

[@JonathanAdami]

This is mindblowingly professional. I'm nowhere near doing any of this but I really appreciate the way it's presented and the thoroughness of your videos! Your work is impeccable!

[@MrCarlsonsLab]

Thanks for your kind comment Jonathan!

[@tenrabbits3069]

Join us for a great day

[@tenrabbits3069]

SSS 10 BOMB

[@tenrabbits3069]

UPDATED : SSS 13 BOMB

[@Shanaigins]

I find it hard to understand why over 150 people could have marked this video with a thumbs down. I for one found this educational and important. thank you for sharing.

[@tevya017]

that's 150 sad and envious people.

[@pmac2056]

Holy Cow!! 52 years as an electrical/systems/test/hobbyist engineer (analog and digital) with a BSEE and MSCS and I NEVER KNEW THIS. An outstanding explanation that explains why a troublesome noise issue is occasionally fixed by simply replacing what appears to be a perfectly good capacitor. If the band marking is only randomly the outer layer (and it's obvious in retrospect that it happens because the marking is being done last on caps that are dumped onto various conveyor belts during manufacturing - Duh!!) I'm astounded that sensitive circuits work as well as they do. I doubt that one engineer in a hundred knows this. Thanks for the great explanation, great design process and an outstanding little test tool.

[@pepecohetes492]

Great video! More than 35 years in electronics and I did not know this. Cheers.

[@MrCarlsonsLab]

+pepe cohetes Glad you enjoyed the video pepe!

[@Satchmoeddie]

+Mr Carlson's Lab I knew about it, and I suspected those lines were erroneously placed on the components, possibly at random. It is a good thing they don't mark diodes for a living! I have a very nice LCR bridge, and the O Scopes, but that little test jigger could be rather handy. I usually run all my caps on the LCR just for GP, and a piece of aluminum foil in hand will verify the shielded lead, or outer foil, by showing a higher C reading on the LCR between the foil and one lead over the other.

[@MrCarlsonsLab]

Thanks for your comment Seth!

[@JimTaylor42]

+pepe cohetes Similar with me too, only it's 55 years. Mr Carlson, would you sell me one of these gadgets? Excellent video - I will subscribe.

[@MrCarlsonsLab]

Hi Jim, If I had more, I would. I'm going to make a self contained unit (no scope needed) in the future. At that point I may make some extras. Thanks for your comment.

[@echobot]

Over 40 years in electronics and I didn't realise that the markings were useless. There you go... always something to be learned. Love your material !!

[@simonlinser8286]

i swear I've built circuits and double triple check as in looking up to make sure i didn't get it wrong in terms of the markings on electrolytic caps. but somehow they still don't work. but i never know because the caps might be too old, maybe they're fake (more recently when i bought some on Ebay...i always struggle with electronics and it's really discouraging because ive built good circuits before, but it just seems like i always screw it up somehow and even if i check the schematic over and over and over i can't find why my circuit doesn't work. but i don't have good test equipment. somehow i still think it's worth it though.

[@xminusone1]

@@simonlinser8286 Many parts are fakes these days. I have old equipment and my circuits and repairs are working. I buy my parts from reputable dealers only. Especially transistors and capacitors.

[@foobarmaximus3506]

They are not worthless. Buy quality parts / caps - and don't worry about it. Unless you're planning on manufacturing capacitors, this is not relevant.

[@paullesho]

I love to hear these old tube radios work as they did when they were new. I am always looking for them to rebuild and play again. I have spent hours watching these very informative lessons you produce. Patrion, yes ! Thank you for your help Sir.

[@martinkuliza]

I'm convinced that with each passing video Mr Carlson is actually getting younger

[@lgregg2478]

I was viewing your video for the second time, and continue to amazed how valuable this video is to so many people. I have enjoyed their comments about what they did in their jobs, and what they have learned.

[@502deth]

this is awesome. easily one of the best electronics tutorials i have ever seen on youtube.

[@tonygriffiths2485]

I have seen this before, but for some reason I was able to concentrate more this time. I always remember the instrument you created for sensing dysfunctional components or parts of a live circuit. You make electronics so pleasant to learn/refresh, even to previous electronic engineers who have spent many years off the bench, like me ! Thanks :)

[@Nirky]

I just tried this with a $50 USB oscilloscope & a variac. IT WORKS! I just sat next to my variac, turned up to like 25 volts but nothing was plugged in, connected scope leads to a capacitor and injected a sine wave signal through my fingers. Switched leads and sine wave was bigger. Ya! I'm not going to build the tester, I'll just check all the film caps as I go building an amp. Thanks Mr. Carlson!

[@jeffroberts3136]

I had no idea this was even an issue. After watching this video, it makes perfect sense. Thanks for education!

[@MrCarlsonsLab]

You're welcome Jeff!

[@BertGrink]

I had the exact same reaction. I don't even mind admitting that i felt a little stupid for not realising this on my own. After all, it's so obvious in hindsight. ;) A *BIG* thanks to Mr Carlson's Lab.

[@1903A3shooter]

Learn something new everyday. I had thought that the line still meant the same thing as in the old days, Another great Vid, Dave W4GSM

[@acidfuzzpedals9986]

Thank you Mr. Carlson. Using your jig is so much easier than testing the thousands of caps I've done over the years by hooking each up to the Hantek. This is a great service to the electronics community!

[@DonalKavanagh1963]

Hello there Mr Carlson. I hope you read this comment. I've been a Subscriber for a few years and want to let you know how much I appreciate all you do. You are up there with the best on KZbin in my opinion and I wish you many more years of increasing success. Thank you for your expert presentations and commitment to excellence. Just wanted you to know..

[@kenmacleod9732]

Thanks for this great video. I'm retired from 50 years in the service industry. Always installed these caps with the band considered the outside foil. Wish I knew this years ago.

[@chrispotts2010]

Impressive and very informative video. As a seasoned electronics designer, this subject never occurred to me when using foil type caps in hi-Z circuits. Congratulations on yet another great video. Thanks and keep up the good work.

[@donmoore5716]

My dad worked at Western Electric and Bell Labs, retired in '69. He taught me about the foil. This is a great refresher, and shows the reason it is important. Nice job.

[@MrCarlsonsLab]

Your father was an intelligent fella. So many people do not know this, or fail to see it's importance.

[@derofromdown-under2832]

Once again, an excellent vid and presentation. One valuable bit of test gear and very many thanks for sharing this... 10/10

It's one of the "top secrets of making a noise free tube amplifier". People sometimes doesn't belive when I do some maintenance on their amplifiers and they get it without any noise, humming, etc hahaha.

Mr Carlson, do you have this three way switch that they use in Tube Testers or does know where I can buy them? I'm trying to buy one to repair my tube tester. My switch have A LOT of rust =(

[@MrCarlsonsLab]

Navarro Eletrônica Thanks for the comment Navarro!

Christiaan Baron Yes! You need to take off them before testing! I usually 100% recap even good capacitors cause everything serviced here have 1 year of warranty. In 8 years doing repairs only one single amplifier came back faulty.

Christiaan Baron And doesn't forget to decouple with 100nf plus 100nf and 10ohm the power supply after the retifier! It get some noise out of the supply lines and give more attack for the tube amp.

[@MrCarlsonsLab]

Navarro Eletrônica That may be another video in the making :^)

[@diggerpete9334]

Great video. I could listen to you all day. Thanks for sharing your knowledge.

[@MrCarlsonsLab]

Peter Byrd Thanks for the nice comment Peter! More video's like this to come :^)

[@papaluvspi]

Amazing amount of information in

[@MrCarlsonsLab]

Your welcome!

[@harriemunnik6977]

This makes a huge difference in sound on my soundsystem. Thank you for the explanation.

[@MrCarlsonsLab]

You're welcome Harrie!

[@MrCarlsonsLab]

HEY! The PCB layout, component map, and schematic are now available on my Patreon page. All the information you need to build your very own. Check out the community section to see other Patrons versions as well. Here is the link: www.patreon.com/MrCarlsonsLab P.S. if you like my videos, there are more on Patreon as well.

[@veronicastaturtusca1988]

This seems so obvious. I never knew of or thought about this. Blew my mind. Awesome video

[@kidureza2]

In the beginning, when I was a teenager, I used the phono-ceramic input of my amplifier and watched the volume of the snorer in the speakers ... and it worked well! Greetings from Brazil, South America.

[@towerclimber7277]

Yet another reason this is by far the best channel on KZbin.

[@martinda7446]

I have to thank KZbin auto play for bringing my attention to your channel. As you opened the subject I had a slightly skeptical hat on, but as you continued I began to wonder if there was anything else so basic I had ignored for years? Brilliant video -outstanding,

[@MrCarlsonsLab]

mart fart Thanks for the comment!

[@RetroPlus]

I don't know anything about circuitry but i'm learning so much from watching your videos, this is amazing

[@audiodood]

Yeah this is a good channel.

[@michaelcane3918]

As a 'semi retired' EE, I really enjoy your videos. You are the kind of guy I'd like to sit down with and enjoy a few craft beers and talk nerd junque. Thanks and Regards

[@ronniehaywood2725]

Thank you for posting this I am a newbie to tube radio restoration and grateful for any tips I can get. It seems from the comments I have got on this one from the start when the old hands didn't know about it. Best regards Ron H Lancashire UK.

[@modularmuse]

Great stuff, explained well. I've been looking for this information for years.

[@MrCarlsonsLab]

Glad you enjoyed!

[@springwoodcottage4248]

Thank you! This was super useful to me, both in educating me of the need to have the capacitors the right way around and in inspiring me to think and create test jigs. Thanks for sharing!

[@ppanzer7243]

Decades ago I learned all these stuff, even the technology of tube amps. You are absolutely right! Thank's alot for your explanations

[@lukystreik]

Your Channel is amazing. I am a electronic hobbyist since mid eighties and radio amateur. But thanks to your channel I'm in progress to get even better in doing my work. Big thumbs up. Thank You for sharing your knowledge!

[@MrCarlsonsLab]

Glad to share Gustav! Thanks for your kind comment.

[@ultrasparc]

WOW... never heard about this before. Learned this new information from here today. Thank you very much. I really need to buy an oscilloscope..!

[@Joe-xe6ev]

THANK YOU for all these amazing videos! Hopefully the few negative folks on here don't discourage you from continuing doing these. What you're doing is awesome, inspiring, and re-igniting my love of electronics and the love that others have too. PLEASE keep up the good work. ! I just loved the Thordarson T20W40 amp video!

[@MrCarlsonsLab]

+Joe Strabley Thanks Joe!

[@jimmorrison2636]

What an informative video. Like some others I was unaware of the polarity issue, I always thought only Electro caps were polarised. Thank you so much. Cheers from Down Under

[@chriscimino7854]

I been in TV repair business for 35 years and I really enjoy how brilliant you are. I think the foil identifying device you engineered is great. I need to build one but for now I have to use a scope and a signal source. I restored a McIntosh 275 tube amplifier and all of the dy film capacitors we're oriented correctly but I was surprised to find that on eight of the capacitors the band was not marked on the shield and six were. I also found out I didn't have to replace them because they were not the unreliable paper types. One of the electrolytic blew its black tar out and made a mess so it got all new electrolytics. One of the 6550 did not have any emissions. It got all new caps anyway and I tested for foil side and made sure it went to the low impedance side. Now the amp plays beautiful but I was really surprised about the band. I even tested a wax paper I had laying around and it was even written FOIL SIDE with the band and it still was wrong. I wish I could send you those

[@MaxKoschuh]

Hi. I'm really impressed that you were using a vintage Tektronix 547 "for real", and that it's not just for display. And your video was really helpful. Even though I'm quite experienced with capacitors, noise, hum and impedance, it was very interesting to "see" the differences of the polarity. I'm experimenting a lot with coupling caps, but I have never had the polarity (of non-polarized caps) in my mind. Happy to see your next videos. Kind regards, Max (Austria)

[@MrCarlsonsLab]

Max Koschuh Thanks Max! Glad you enjoyed the video.

[@bobsbarnworkshop]

Cool circuit! I worked at Westinghouse, Kodak and a leading university and did a lot of r&d and had to build a lot of simple test circuits and test beds like this! I’m going to build it but just use a dpdt switch to swap polarity and watch the scope! Let the toggle point to the grounded lead. I always thought the caps were marked correctly!!! Thanks for the heads up!

[@NickHumphries-ey5vm]

Yeah a DPDT is fine. Keep it simple!

[@SuEnRoD]

Excellent info and video. 30+ year tech and always noticed the band but never realized the significance. Thank you...Learned something new to file in synaptic storage :-)

[@davidmuriungi4122]

I Love your detailed almost scientific explanations !!! Keep up the good work !!

[@georgelewisray]

VERY helpful and VERY educational . . . thanks!

[@stuarthossack7906]

Yet another obvious thing I didn't appreciate, never knew about, never read anywhere and was never told. I've been building circuits for around 40 years now and I'm now wondering what circuits I can/could go back to and tweak. This could even have been the source of oscillation in some circuits where I'd swapped out a capacitor to cure and now I see I could possibly have left the value the same but reversed the component!! Ya live and learn, what other obvious stuff don't I know??!! Jeez - Thanks for the insight, Cheers Mr Carlson from the UK :o)

[@MrCarlsonsLab]

+Stuart Hossack Glad you found this helpful Stuart. Thanks for your comment!

[@FixItStupid]

+Stuart Hossack Me To Going To Check The Last Amp I Did .... Wow The the manufacturer, miss led us all ..... I was taught that The Line was the ground and/or the foil side

[@williammackie6691]

Stuart Hossack p

[@hahaagi]

Live and learn. Great comment.

[@ronb6182]

I was taught the line was negative but these china parts did not mark the capacitors right. I had friends that took electronics in high school and they helped me in hobby electronics, I wanted to take electronics but my math skills were poor. I can use the computer to get math questions solved now. he he

[@towerman75]

Where was Mr. Carlson when I was in college. To be so young, and have so much knowledge, and able to explain everything in a way that anyone can capture his meanings. As an Engineer (retired NASA), watching his video's are not only informative, but enjoyable. I'm 74 years old, and when first starting my career, everything was tube technology. I had to learn with the changing of times as we moved into germanium, to silicon, and some SMT (luckily, I retired before it got to heavy). The transition wasn't easy for me, the professor's I had moved at a very fast pace, and you either got it, or with help from other students in the class, did the best you could. The actual knowledge came from the field where you used what little you had learned, and hands on taught you. I hope Mr. Carlson stays on line, I really enjoy the video's and his skills.

[@janiwindsor]

Your channel became my favourite one. Subscribed and supported via Patreon. After 16 years of "experience" I have a feeling that from now I can learn some really useful stuffs from you. You are Legend Sir. Thank you.

[@cny02253]

Clever Paul! I like it. I have a little rig using a DPDT switch in an Altoids tin that I use for this -it works and ends the unwanted capacitor juggling. Low part count, no IC's to zap. Sans LEDs -the switch lever points to the Lo-Z lead (foil out lead) . Circuit and concept is basically same as yours, just more caveman.

[@MrCarlsonsLab]

cny02253 LOL, Caveman made me chuckle! Hey, what ever works right. Thanks for the comment....LOL

[@robertcalkjr.8325]

cny02253 Instead of caveman I call it Flintstone.

[@russellhltn1396]

Thanks cny02253, I was going to say that a simple DPDT switch would seem to work just as well - and never worry about having a battery go bad right when you need it.

[@markgigiel2722]

Watch out, the Altoids generate a lot of heat.

[@alanlevin167]

I wondered about this--why the circuit, battery, led's..............I'd go with the DPDT switch in the box, every time!

[@amj5909UTUBE]

Awesome information & presentation. I knew the importance of electrolytic polarity. I never knew in my 40 years of electronics since the USAF of this and now appreciate learning of the difference in non electrolytic capacitors circuit orientation. You would logically think a capacitor manufacturer would understand this and come up with a standard and manufacturing process to identify the band end. It seems they may not know what you do and that would not be too surprising. You are a special person!

[@gianlucavessio3562]

You're a real genius! I'm learning so many things looking to your video lessons. that's what a teacher has to be... thank you! 🤗 🤗

[@alengregorin8366]

Hello, i just subscribed. Thank you for doing this. I'm 30 and didn't had a chance to get such education so i'm learning now. It really means a lot that i have a chance to learn from yout videos. Kind regards from Slovenia.

[@hds0405]

Outstanding explanation. Learned something new and extremely useful. I'd like to try a 556 configured as a D-type flip-flop (manually push button triggered instead) along with the CD74HC4066 since I'm using through-hole PDIP components to reduce the parts count and circuit footprint. What a great project, thank you! You've gained a new subscriber :), cheers!

[@marvinbrando]

Great channel. Learning lots. As a guitar tube amp guy, I wondered what other people are doing to test for polarity of supposedly non-polarized caps and found Acid Fuzz Pedal's channel's video on their capacitor polarity checker. Using just a fuzz pedal and a guitar amplifier, he just touched the capacitor leads to the signal tipe and ground sleeve of the the instrument cable and you can clearly hear that one direction is much quieter than the other direction. This seems to be the same noise test as Mr. Carlson is addressing, but I'm wondering if it's as reliable/good as Mr. Carlson's tester. (I see some discussion in the comments about why a simpler tester using a switch might not be reliable, but I didn't follow. I'll have to watch this video again and read through the comments.). Really like this channel.

[@theofficialdiamondlou2418]

That’s a great idea. I was wondering if ways to do this with what I already have (not wanting to buy an oscilloscope as I’m just a player looking for “my sound” ) Having recently changed the caps in my guitars , one guitar started to have a BAD hummm . Now I know why , AND how to test it and most likely fix the issue. Thanks.

[@tiger12506]

This is fantastic! A concept I wasn't aware of, and a gadget build that I would find useful. Sweet!

[@CraigHollabaugh]

Mr. Carlson, I've been a EE for 30 years and never thought about what you covered in this video. Excellent coverage, will start paying orientation attention during all future amp builds. Thanks for the excellent tip. Craig

[@MrCarlsonsLab]

+Craig Hollabaugh Your welcome Craig!

[@camarol88]

Thank you very much for the video, I noticed that something was happening on one of the channels of my Headphone vacuum tube amp because I had hum from somewhere, then I did the inverting of the cap that goes to the plate and not any more problems.

[@MrCarlsonsLab]

George T Glad to hear this helped George. Thanks for your comment!

[@mikerama4724]

Why didn’t I know this? I learned something today 👍

[@RadioWhisperer]

Great info, well explained, and the production quality is top notch. Thank you for what you do! Would love to see more on the diagnostic process. I'm looking for the ones you already have, I'm sure there are several at least..

[@medhawk4885]

All I can say is "WOW" ........I'm going to try to build one of these and it makes perfect sense to me the way you have explained and demonstrated it. Thank you again.

[@MrCarlsonsLab]

Thanks for your comment!

[@rosshollinger8097]

So, do you ever take apprentices? I can sweep a mean floor and make great coffee. :) I watch everything you do very closely and learn a lot. I feel fortunate that, as a newbie, I'm learning things at the same time as old timers are. Doesn't get better than that. Thank you.

[@paullesho]

I know what you mean sir.

[@dave-d]

So, a particular equipment model may have different signal to noise figures depending on what day / who assembled it etc. Very interesting indeed. Thank you. (P.S. I would pay just to sit in that lab!).

[@scotthuber7261]

Thanks so much for your terrific work and great explanation of the operation of all the components. As a self taught electronics fan, your videos are a true treasure chest of information....now back to my world domination machine...

[@rogerkerr5745]

Great video, pleasant, concise, and complete! Always a pleasure learning from you.

[@MrCarlsonsLab]

+Roger Kerr Glad your enjoying the video's Roger. Thanks for the kind words!

[@MichaelBeeny]

For people without a scope, one could also use a very simple circuit that uses a small but sensitive audio amplifier with a diode on the O/P connected to an analogue meter. This should clearly show which way round the capacitor needs to be by how large or small deflection is. It might even be possible to replace the meter and diode with a loudspeaker and hear the difference. Even a domestic or HiFi amplifier that has as mag input at about 2/3mV should work well as the input is sensitive and has RIAA EQ (ie bass boost) Be careful with levels, you don't wont to damage your loudspeakers!! or just buy a scope!! and make Mr C's tester.

[@MrCarlsonsLab]

Michael Beeny Sounds like another great idea! Thanks for the comment!

[@stevenking2980]

I built one of those! Have to do a video...

[@MrCarlsonsLab]

You should, Then come here and let us know about it.

[@stevenking2980]

My video would be really bad in comparison to your knowledge... Been watching your stuff, wow incredible insight! Good stuff man. Really impressed!

[@MrCarlsonsLab]

Thanks for the very nice comment!

[@frankandstuff]

Can you upload a document with the diagram and the parts you used? It's hard to figure out from the video. (5 mV is the minimum accuracy)

[@amoruzz]

I preached on this subject of outside foil for decades and was called a heretic. "Outside foil to ground" Thank you for this good video! 👍

[@TheSpotmaticii]

I've been doing stuff with solder and wires for over 50 years, I never ever considered this. I tried it and you are right....it works and I cannot be sure yet, but you may have solved a hum problem I've been having. Thank you very much.

[@MrCarlsonsLab]

+Paul Goutiere Glad this helped Paul!

[@cerealexperiments8865]

I like this technique, I finally tried it out in replacing some paper capacitors with film capacitors in an old GR megohmmeter. But I find it easier to get a clear indication of which way is best with a good analog ac voltmeter with a 1 mV range.

[@johnking2551]

I have known for years why we need to know which capacitor lead goes to the outside foil, but I am shocked to learn that we cannot trust the factory marking!

[@peterream9437]

If only i had a neighbour like you Paul. Its awakening my hobby of diy electronics

[@TheRmoroni]

very interesting don't recall seeing or hearing about this before .going to watch all your videos for more secret stuff! thank you!

[@Inquire98]

"Thank You", thank you very much😎 May I have a link to your capacitor test circuit🤔 Let me know, I look forward to hearing from you

[@goodboyringo9716]

This is Mr electric, he can be believed , plain and simple.

[@RickSaffery]

Your video is world class both for superb content and production quality. All of your clips are exemplary and raise the bar high. I look forward to watching all of your content. I will build this test box using through-hole components, easier for me. I may also build a second test box using an Arduino to do the heavy lifting. Thanks for producing the clip and providing inspiration for building a fun and useful piece of test kit!

[@degingerninja]

I came here for a few seconds of information I needed but stayed your voice is so easy to listen to Omg, glad I found you P.s you also know your stuff xD

[@owenaero]

is there a tester you can use that does not require a scope for checking these ?

[@imqqmi]

It should be easy to use and arduino or other microcontroller to sample at a certain frequency and do peak detection on it. With an lc display you can show the levels in each direction. Or connect an amplifier to it and listen for louder/softer volume. Maybe a crystal ear piece provides small enough load to do it without amp.

[@johnkerley4152]

I mean, your talking about the issue of interference sheilding, but it is not a polarity issue like in DC electronics, therefore marking the line on the one side is not to be confused with the line that would be on one side of an electrolytic capacitor.

[@FozziesRandomReviews]

I've been binge watching your videos for three days now. I think my brain is bigger already. I also start my Masters Degree in electrical and electronic engineering later this year!

[@MrCarlsonsLab]

Glad to see your enjoying the video's!

[@moodyga40]

this is the ultimate bit of knowledge, and it makes the audio circuit work 100% with all hum gone

[@petedazer2556]

You are very gifted sir, and I always learn from your videos, but I must ask, why not just use a simple dpdt switch.

[@esach4136]

Pete Dazer is

[@vicegrip33]

Wow, you sound like my dear departed Dad, he was an electronics guy, I'm a metal worker like his Dad. I use very old Miller tig welders that use two .002 uf mica capacitors in parallel in the H.F. spark gap oscillator circuit. These welders last longer than some humans, but those caps don't! tar leaks out of them. I was given a box of modern alternatives to use, so far two types from Sangamo have worked well. Another wound or layered type he said would work but they are not marked for polarity. I wounder if it will matter, now that I've watched your vid. My guess is it would work either way, but send out H.F. interference more if wired in backwards. Can you advise and educate me further in this application? Thanks. Very neat vid by the way, reminds me of Dad, and I'm 59 so that's back aways.

[@damianjacobs2193]

Thank you Mr Carlson for this golden nugget! This draws parallel to the 'pseudo balanced trick' played in recording studios to reduce hum by cutting shield on the input side of balanced audio cables

[@erichgugle5500]

Very nice test box to determine correct polarity of the capacitor so they can be installed correctly. Another successful demonstration and thanks.

[@Mr71chevyvan]

at 73 i always thought the line denoted outside foil.you showed i was wrong. i'm not building anything as i am satisfied with the earlier experiment showing the where the outside foil is by introducing a signal with your body. i hope my electrolytics are correctly marked :>) barry

[@paulf1071]

Anybody know how close you need to be to a mains source for the 60Hz to be induced into your body? This tester looks to work great, but what if you work in an environment where there's a lot of high-power and high frequency switching gear. Coupling the mains signal to the cap under test via your finger, may lead to situations where it's difficult to tell a small signal from a larger signal on the scope screen...??

[@napalmbatsmusic8352]

and how can i check the proper direction without an occilliscope cause there expensive

[@jordanrodrigues8265]

You can listen to it as long as you have an amplifier with high input impedance and high enough gain. If the amplifier is grounded to the building's wiring there will usually be plenty of power hum on your body. If you can hear it, you can detect it. While holding the capacitor body try connecting it both ways. It's quieter when the outside-foil is connected to the signal ground. A high input impedance is needed, so a FET source-follower circuit will likely improve performance. So you just need a FET, battery, two resistors, one capacitor, a couple alligator clamps, and a way to connect it to the amplifier or input. A Zener diode to protect the FET from static is a good idea but not strictly necessary. A sensitive AC voltmeter also works.

[@andrerouth4253]

What everybody else said!! I also built CNY02253's double-pole, double-throw passive version but without the Altoid's tin! Your solution is useful, professional, AND a great project. Thank You!

[@anathema771]

thanx sir. what a great video. for years I thought these caps dont have polarity or any particular direction and I was wondering why and its very obvious now . very recently I worked on an amplifier circuit and it was picking up some noise regardless of all the efforts to pin point the problem and after watching this video I made those corrections and it became absolutely quite. wonderful!

[@nevillegoddard4966]

The whole idea of the outermost layer of metal foil of even an unpolarised capacitor serving as a shield seems so obvious now that it has been pointed out to me, that I wonder why I didn't think of it before? D'oh! So you have your proof then right there! I just tried it with a coupla 0.33uF/630V new cylindrical yellow capacitors very similar to what Paul uses. I was using a little 200khz 2" colour LCD cro from jyetech that I built. On maximum sensitivity, I could discern a difference in noise when reversing the cro connections! Not as clearly as shown on Paul's cro, but enough to be able to confidently mark the 'shielded' end of all my previous to now non-polarised caps!

[@TERRAOperativeOriginal]

Mr Carlson, would you mind releasing the PCB layout?

[@MrCacciLLo]

Yes, the video is really good also the idea for the project. It would be great to have the pcb layout. Would love to build this tool but me and a lot of people don't have the right knowledge and experience to design a pcb layout for this, although with a pcb we could easily build it. Thanks

[@ronb6182]

you could use vector board instead of etching a circuit board.

[@besanit]

I bet you can get it from his patreon page

[@DonBonin]

I have a cheap 2 channel, 100mhz digital rigol scope (DS1102E I think it is) and even using a coax cable I can't reproduce the high/low noise effect by touching the cap. I have it set to 5mv per division. I'm not sure what I'm doing wrong. Anyone have any suggestions? The caps I'm testing are 650V orange dips, if that matters.

[@rickgoebel6724]

I am getting the same "no difference results" from both of my scopes, 3 different types of coaxial cable and 2 different locations.

[@lingcod91]

Don, I've the same problem and I see Mr. Carlson didn't answer . . . Did you ever get it resolved?

[@lingcod91]

Rick, I've the same problem and I see Mr. Carlson didn't answer . . . Did you ever get it resolved?

[@RC-Flight]

Don Bonin I have the same scope and same issue. Are you using the stock probe that came with the scope? He uses just wire in this demo no probes with components built into them.

[@garybevis8691]

@@RC-Flight Hi Guys, I know Paul is very busy especially with Patreon and he is making a very good living producing these videos. He responds very quickly to Patreon members as I am one and have had many helpful conversations via PM there at Patreon. As for the problems with the Digital scopes I think it may have something to do with the actual EMI noise in ones shop/lab area. I have read many people having difficulty with this issue regarding inconclusive results with OSFE (Outside Foil End) testing using DSO scopes. The body grounding may be some of the problem but I have a feeling it is the digital scopes and the way that they capture signals. I have no modern digital oscilloscope so I cannot test this theory as of now. With my Tek 2246 I have no issues whatsoever determining the outside foil end of any capacitors I have tested from 47pF to 82uF.

[@Theineluctable_SOME_CANT]

This seasoned, very experienced EE learned something! Well done!

[@peteschreiber9517]

I just found your site. It's GREAT! You are an excellent teacher. I hope you make a lot of money.

[@MrCarlsonsLab]

+Pete Schreiber Thanks Pete! I haven't made a penny off KZbin. One day I may Monetize the channel.

[@Kennynva]

How do you make something similar..that would not require an oscilloscope???

[@sorrylifeless]

Connect capacitor before your amplifier input, orientate capacitor and listen, whenever you satisfy the sound, you got it right.

[@bikingmnviking3801]

Standalone unit is what it looks like from the video thumbnail, too. When he was insisting on a metal box what I thought he was going to do was either amplify the AC hum or more likely use a new test frequency and have the metal box be the antenna for this circuit. This way you don't need to put your fingers on the cap each time OR have it hooked to a huge power-sucking scope that is not field friendly. The signal would just be transmitted to the cap's foil. What you ideally want is an oscillator circuit that makes a signal that has a maximum power transfer to the average size of the cap being tested. (2-4 cm) But probably any frequency would work. Matter of fact I'd probably put a strip of plastic across the top of the box and a wire over that so it is used like a miniature antenna and the metal box would act reflectively to keep the signal directed towards the cap to assist in eliminating false readings. Then have the circuit have an op amp connected to one bicolor red/green LED. When it lights green that is your foil end. Much less fouling around. Tune the op amp input with a simple Twin T oscillator. en.wikipedia.org/wiki/RC_oscillator#Twin-T_oscillator In fact with a dual op amp chip this could all be accomplished and probably with an even lower current draw. As a plus I might add in either a beeper of some kind so even a blind man could use it. I knew a blind guy who could repair tape recorders. He'd probably love to be able to take his hobby further and I do know of several blind people on YT who seem to live for the interaction in the comments. There is even a blind woodturner on YT!

[@PhunkBustA]

just make a scope out of an old crt tv ;)

[@SGspecial84]

You need more oscilloscopes :P . Do you have a recommendation for a good affordable one I can pick up on ebay thats reliable?

[@Leadvest]

If the seller explicitly says it still works, the manual is available online, it's $20-$50, and 20-30 years old, it should be fine. Yes, it's actually going to take some effort to track it down, and yes shipping is going to be expensive.

[@coreychambersmusic]

I bought this one... Got mine off eBay. Works great, especially for someone like me who is only going to be testing caps for my electric guitar and amp. www.robotshop.com/en/seeedstudio-dso-nano-v3.html?gclid=COiGzOOWjdECFQKewAodiIUO-g

[@wildrootsfarm1975]

Amazing device created. I appreciate the thoroughness. Thank you.

[@2wattsout]

Excellent video. Thanks for taking the time to make this!

[@MrCarlsonsLab]

+2wattsout No problem, glad you enjoyed!