The Magic Hiding Inside Your Incandescent Holiday Light Strings!

[@MrCarlsonsLab]

To learn electronics in a very different and effective way, and gain access to Mr Carlson's personal designs and inventions, visit the Mr Carlson's Lab Patreon page here: www.patreon.com/MrCarlsonsLab

[@God-CDXX]

the nominal voltage range to trigger the the shunt is about 30 - 70 volts AC PS they are also function as a 3 amp fuse. this is my result of a teat on 30 bulbs. my test rig is a vintage variac transformer in to a 1 - 3 isolation transformer the amp meter reads op to 5 amp in 1 ma increments

[@God-CDXX]

the voltage range changes if air gets in

[@God-CDXX]

my test load is a 60 watt 120 v bulb

[@salihm4268]

How many volts can I power this small bulb? What is the limit voltage?

[@japanskakaratemuva5309]

please next time announce what you are going to do while gripping the glass between the steel vice jaws while holding it with bare fingers. I'm not sure why but it triggered serious 'please wear gloves' which you did .. and everything went fine. so ... next time just say in advance first what's going to happen next and all will be fine. 😅

[@adamdavies163]

Also worth mentioning is that most sets incorporated a safety or fuse bulb, usually identifiable by a white tip. This bulb does not incorporate the 'shunt' wire so is designed to cut power to the set when too many bulbs have failed and the voltage across the remining good bulbs exceeds a safe value.

[@MadScientist267]

The fuse is in the plug 🤦‍♂️

[@kyoudaiken]

@@MadScientist267 Not everyone has these bulky unwieldy ugly but very safe UK plugs with a fuse in it. UK is not the world.

[@matthewbaker6827]

I thought that was a flashing lamp, bimetallic?

[@MadScientist267]

@@kyoudaiken Umm.. They're in the *light string plugs* Reading comprehension not a strong point for you I presume 🤦‍♂️

[@kyoudaiken]

@@MadScientist267 Ours only have mains plugs and that's it. There's no other plug.

[@duroxkilo]

fantastic educational work :) my neighbor is a decoration lighting maniac.. we're good friends, he enjoys scaring me every chance he gets because i jump in the air like a spring... to pay back for his ruthless behavior, i mess w/ his Christmas lights. it brings me great joy. one year i climbed one of his mesquites and inserted one of those intermittent bulbs in the top strand. as soon as he turned the corner coming from work he understood what has happened... so he got a spare bulb, climbed the tree and found the culprit as it's marked w/ a red dot. a few days later i inserted two intermittent bulbs but only one had the red pain scrapped off. he repeated the procedure... but as he was victoriously walking away, the second blinking bulb had reached the working temperature and kicked in... that created a dilemma of sorts or maybe thinking occurs slower while hanging in a tree because he was up there for a minute. i am open to input, anything nondestructive is a go :) happy holidays everyone!

[@richardgoebel226]

Only on Mr. Carlson"s Lab would we discover the secret behind those little bulbs. 2 thumbs up.

[@jrkorman]

Except that Fran Blanche's channel came out with a very similar video on this very subject and "scooped" Paul by about 24 hours. Paul, however, goes into a bit more detail RE: the actual mechanism involved.

[@richardgoebel226]

Yes. i just spotted it

[@leybraith3561]

I Note With A Wry Smile That This Is One Of Your SHORTEST Videos Merry XMas

[@goingjag]

Frans lab discussed this yesterday and someone suggested it would be a good topic for you Paul!

[@vwestlife]

I just watched Fran's video about it. My guess was that the bulb's filament holds the leads under tension, and when the filament fails the leads spread apart and the wire wrapped around them closes the circuit.

[@GothGuy885]

that is how I asumed it worked also. but after watching this video it "Shed a new Light" on the subject

[@1pcfred]

Filaments are usually coiled. The stuff seems to lack any tensile strength to me so I don't see it holding much apart. Plus I'm pretty sure it expands as it heats up too. Which is part of the reason why it's coiled. To compensate for that expansion. I've seen filaments in bulbs move as they heat. We use tungsten as a filament because it handles the heat the best but that still doesn't mean it handles it great. I mean the stuff is glowing so it can't be good for it.

[@turnbullfl4114]

Decidely answered Fran's question.

[@ELECTROxigeno76.]

Incredible video, engineer, I never thought that this was the reason why these lights remained on even though the bulb was blown, incredible. Congratulations, engineer.

[@donmoore7785]

Love that you used a vintage capacitor tester to demonstrate the breakdown voltage - brilliant!

[@MrCarlsonsLab]

Glad you liked it!

[@chungaleta1234]

I wish you'd been my electronics teacher. You explain things in a way anybody can understand

[@dave1135]

I remember the old versions, if it burned out, the whole string went out. So you had to spend a hour taking a known good bulb and substitute every bulb with the good one until you found the bad one. Worked great unless you had more than one bulb bad. Sonetimes it was easier just to buy a new set. You could find the bad one if you had one of the little bulb testers, but you still had to pull every bulb

[@MatthewHolevinski]

I remember one year stringing them all out on the kitchen floor and going through them with my grandma, doing just that. While swapping out bulbs, somehow, someway, I accidentally jammed my finger down in a socket, I think maybe i'd dropped it and I was just picking it back up and the whole strand spun on me. But as soon as my finger went inside that socket my hand and face exploded, it was awesome, my face looked like someone had thrown a bunch of soot on me and my hand was black. Ahh, the good times, I sure do miss my Grandma.

[@SPINNINGMYWHEELS777]

anyone old as dirt remembers that 😂

[@rwfrench66GenX]

I remember looking for the bad bulb only to find out the bulb I was using was also bad! D’Oh!

[@JB-fh1bb]

Funny “if I knew then” I could have used an ohm meter and binary search to find the bad bulb in a minute or two.

[@keithv708]

Same here

[@kristyskirt9015]

That IS a Bright Idea. Must say Mr. Carlson knows really knows his test equipment too.

[@McTroyd]

Yay! Fran Blanche did a video on this but it was kind of inconclusive. Looking forward to the Carlson treatment of this question. 2:47 - No need for cringing. I've never seen a working vise that looked pretty. Even machinists seem to mar them up, as long as they aren't the precision surfaces marred. 9:45 - Love the use of the old leakage tester for this. And this video reminds me... I still haven't implemented your diode dropper trick on our incandescent lights. This needs... rectification... 🤓👍

[@adrianoragazzo1321]

There's not that much to understand and Fran explained everything so nothing about "inconclusive" .

[@JCWise-sf9ww]

Goes to show how much more Mr Carson's knows technology.

[@McTroyd]

She seemed to be leaning in the direction of the wrapped wire being a mechanical contact. I didn't see how that would work without prematurely breaking the filament. This makes more sense. @@adrianoragazzo1321

[@BloodAsp]

Apparently Fran isn't too happy that her explination video she was gonna post next got sniped. In fact, she posted about it on the community tab, and removed her original video.

[@dosgos]

@@BloodAsp Fran's original video was brilliant! I hope she puts it up again.

[@terrylindsey3294]

Dude, I am almost 60 years old and never knew this. That is so awesome, thank you.

[@BretFrohwein]

FranLab just had a video about these.. thanks for your demonstration!

[@anthonyshiels9273]

Wishing you Paul, your family, friends and everyone at Mr. Carlson's Lab a Very Happy, Peaceful and Holy Christmas and best wishes for the New Year.

[@MrCarlsonsLab]

Merry Christmas to You and Yours as well Anthony!

[@tomohlsson9045]

OK, nice presentation and great explanation. I'm assuming you'll follow up tomorrow with a video demonstrating the complete restoration of the bulb you opened up, correct?

[@pedrodepacas4335]

Seriously, you and franlab both doing a video on tricky light bulbs.

[@larryh8072]

Mr C didn’t use a hammer to reveal the secrets inside the bulb:)

[@kb1kos]

I LIKE your drill press vise. The little bits of slag and other scars on the jaws add character.

[@jonelectronics510]

Scary how Fran at Franlab did a video on this yesterday!

[@redace01]

You and FranLab are vibing the same wave! :D

[@michaelardai9703]

Back in the 1880s, a similar system (the film cutout) was used with streetlights. A high voltage supply and series connected bulbs, with a self-shunting socket. See patent 818253. This used a thin insulator between two spring contacts in the socket that would arc through when exposed to the high voltage

[@georgemoore5307]

We used that in a string of 300V bulbs (6 I think ran very dim)used to limit grid current in a 1 megawatt induction heater. Porcelain base had clip to hold the shunting fuses that you could replace if the bulb failed. used a saturable reactor and 15000v dc supply

[@tedmoss]

Nice, I had to give up on incandescent bulbs a few years ago, and switch to LED's. The old bulbs worked well for many years, replacing candles and saving many many house fires at Christmas time.

[@TomNimitz]

You remember candles on the tree? Well, you are an old timer.

[@mortimergladbreath]

Wow! I'm 67 and have always known about the shunt wire inside the lamps, but until today had no idea how it worked! Why didn't it short out the string? Thank you for such a nice demonstration!

[@PlanetaryThoughts9861]

Yep, I just assumed that the filament was designed to melt itself into a short. I always preferred the C7 or C9 bulbs even if they are energy hogs.

[@vortexan9804]

According to Franlab, every shorted bulb makes the others brighter, so will shorten the other bulbs' life.

[@Rev22-21]

​​@@vortexan9804That's true. Think about it. Fewer bulbs equal smaller load equal more voltage going to each bulb equal brighter lit bulbs equal shorter life. 😊.

[@MrCarlsonsLab]

You are welcome!

[@curtisroberts9137]

I always wondered how those worked. As a kid, I remember having to check an entire string of bulbs many times as one bulb would cause them all to fail. Neat little trick they used there.

[@KeritechElectronics]

A nice, straightforward and science-backed explanation! Insulation breakdown makes sense to me as when the bulb goes open, the mains voltage will appear across it, and as demonstrated, it's high enough for the insulation breakdown. One more thing is the temperature resistance coefficient. A cold filament's resistance is lower than hot filament's; the bypass resistance - as Fran demonstrated - is lower than cold filament's.That's a big problem when those bulbs start failing. Blowing a single bulb won't really change anything, but the more of them go out, the higher the current through the string, the more power dissipation per bulb, and the higher risk of any remaining bulb going out. It will accelerate over time, so if you see a dead bulb, replace it or else you'll have a lot more to replace than just one. Hell, in an extreme case the whole string will get blown and act as a low resistance formed by bypasses, tripping a breaker or burning down if it doesn't happen.

[@Scott-Ferguson]

This shunt is why the light keeper pro is a handy tool to have. Sometimes the the shunt doesn't 'fail' into place (the insulation holds up) and thus the string goes out. The light keeper pro sends a momentary high voltage 'shock' through the string to 'fail' any shunts on burned out bulbs. Pretty ingenious. I've since moved to LED lights but still have my light keeper pro. (please forgive my undoubtedly wrong terminology)

[@jeffclark2725]

Agreed, I didnt realize the second circut in the bulb that has to be shorted before it will connect

[@StealthParrot]

@fersusoncomputing Me too, I bought this this tool a couple of years ago not really giving it much credibility at the time. I thought it might be snake oil but it really does work ... and now it makes complete sense why it works.

[@gorak9000]

light keeper, or any piezo igniter from any bbq your neighbors tossed out over the last year - that's all it is

[@jp040759]

@@gorak9000 I made my own Light Keeper sparker with piezo igniter. Works great. LED bulb strings are a pain in the arse to fix compared to the incandescent. I once worked on a string of LED Christmas lights where all the LEDs failed. As each LED failed short all the rest started going until they all avalanched to death. Strangely there were blinking LEDs in the string and those are the only ones that survived.

[@gorak9000]

@@jp040759 increasingly we're getting the European style LEDs here now too that are all soldered together, with no replaceable bulbs at all. If an LED dies, you toss the whole thing into the landfill and drive your car down to buy-n-large and buy another one. I guess the only saving grace for those ones is they tend to have a low voltage wall wart that fails before the LEDs do. I have an exorbitant amount of Christmas lights, but most of them are of the programmable (WS2811/WS2815) variety - there's a whole other set of issues you run into with those. So far this year I've only had a couple of pixels fail, which is pretty good, but to replace them, you have to chop out the old ones and solder new ones into the string with watertight heatshrink. The price you pay to be a nutcase with programmable Christmas lights synced to music :)

[@inspector1794]

I've wondered many times exactly how that worked, thanks for the clear explanation and demonstration. Enjoy the season and all the best for the new year.

[@MrCarlsonsLab]

Thanks, you too!

[@LutzSchafer]

Hahaha same topic as in Fran Lab. I just wonder what isolation material breaks down at around 100V ???

[@TobiasThede]

You solved my oldest electric mystery,thanks for that,mr carlson.merry christmas.

[@RestorationsbyKennyFidler]

I really like the Christmas video! Merry Christmas

[@MrCarlsonsLab]

Thanks! You too!

[@2packs4sure]

Wow,, I just Googled this a few days ago trying to find the answer to how they keep lit AND not act as a dead short when the fillment is good ! A long time subscriber thanks you Mr Carlson !! It explains the situation I had when I first put my lights up where I had a section that was completely down but after a few minutes it all came back with one dead bulb,, so that resistance wire in that particular bulb must have been slow to react...

[@lqueryvg666]

Using a cap checker to test the "function" of that bulb - Totally awesome!!! Brilliant!!!!

[@laidman2007]

A genius design! Thank you for the explanation!

[@rtronicslab1253]

how incredeble few days ago i watched same type of video on fran labs channel .......cristmas miracle😄....lot of love

[@chrisreynolds6331]

Yes I saw fran doing it yesterday. Christmas miracle indeed. I'm sure us technicians seem to be an advanced species!

[@AgentOrange96]

I saw her video recommended yesterday, but I was headed to bed. I saw this recommended just now and decided to go watch Fran's then Mr. Carlson's back to back. This is a good order to watch them in. Fran poses a question which Mr. Carlson answers. Pretty cool.

[@Rob2]

Oh she is making technical videos again? I unsubscribed some time ago when all she did was whining and complaining...

[@mediaplayer1594]

​@@Rob2That is what Fran did again, he had a hissy fit and took his video down. Fran mostly makes frants (complaining videos) and old films (then complains more when copyright claims against them, he doesn't own the copyright).

[@kenwezeman7827]

Great video. One comment: I noticed that toward the beginning you mentioned that the short in the burned-out bulb caused shorter life for the rest of the string. I guess you assumed that your viewers are able to figure out that that is because the loss of resistance in the filament of the burned dead bulb caused the current in the rest of the string to increase slightly. If you stated that I missed it.

[@hestheMaster]

Fantastic explanation and demonstration of a Christmas tree light bulb and how it works,and doesn't stop the circuit from lighting when it burns out. Merry Christmas Mr. Carlson!

[@MrCarlsonsLab]

Merry Christmas to You as well!

[@W1RMD]

Looks like this a response to Fran's video. I discussed this over there and mentioned your diode modification you did years ago. I've done this to my lights and they're a little dim, but I like that it saves the bulb. My wife thanks you for convincing me to go back to incandescent Xmas lights. Although I still have leds as well. I've always thought that the spreading of the filament holder when the filament opens is what made that wire at the bottom short out the bulb, but this really clears this up for me. It took me a minute to figure out that the bulb would actually see 120 volts with open circuit condition (blown bulb) for a second and it's THAT high voltage that jumps through the insulation.

[@rsdandy]

I have known for some time how the setup works but it was fantastic to see it happen. Thanks !

[@steveoshaughnessy3736]

Thanks so much Mr. C. I always wondered how that worked.

[@MrCarlsonsLab]

Any time!

[@wackojacko3962]

Really cool to know! Two cameras one with high magnification too see the filament breaking down would be equally cool too see. 🙂

[@tritonmole]

Its so simple, and it works almost perfectly. I remember from my childhood that if you let several of those linger in this bypass mode, then it accelerated the burning of the rest of the bulbs :D So we always made sure we replace the first few in time.

[@louf7178]

In case you didn't know, its because the balance of the bulbs have to consume the all the power, thus eventually overpowering their design limit, and catastrophic failure will begin.

[@tritonmole]

@@louf7178 Thanks, but i knew why others failed quicker. When multiple bulbs are shunted, the rest must handle the whole voltage drop thus individual bulb voltage increases as some bulbs are shorted

[@TheSimoc]

​@vortexan9804 Yep, I remember my grandparents having really old christmas light string, and its instruction manual warned about such, advising to replace a burned out bulb as soon as possible.

[@DigitalMediaCanada]

Wow. This is awesome! I love learning little secrets like this. Thanks.

[@MrCarlsonsLab]

My pleasure!

[@Broken_robot1986]

Great minds! Just watched FranLab on these lil magical bulbs.

[@NOWThatsRichy]

I've known about the shunt in these 'permanent contact' bulbs for decades, but was never sure exactly how it worked, I've often looked at that little turn of wire inside these lamps but didn't realise it was insulated wire, thanks for this explanation!

[@romjone4801]

Thanks, I always wondered how that works. I just wish you would have measured the resistance of the shunt and the resistance of the filament. Merry Christmas!

[@samuelfellows6923]

Particularly when testing them with a multimeter, as the “shunt” can fool the continuity function and you think the bulb is working

[@imark7777777]

Fascinating demonstration.

[@coot1925]

I used these bulbs as street light bulbs and to illuminate the inside of buildings on my model railway layout back in the 70s. I found out purely by accident that they ran perfect on a 12V DC transformer and I could dim or brighten them. Looked amazing with the main light switched off, especially as the setting was all steam age and they gave a lovely warm glow. I must have made about 300 lamp posts out of modellers brass tubing and roughly 50 buildings had lights inside. 5 years later and I was still working on it. Truly remarkable little things. ✌️❤️🇬🇧

[@donl1846]

This was so cool and fun, thanks Professor Carlson!!

[@MrCarlsonsLab]

My pleasure!

[@JenkinsUSA]

0:53 - Refrigerator lights magic brother. As a kid I always wondered how that Christmas light worked. 🎄

[@danielgasparek8196]

Merry Christmas and thanks for all the great content you provide…including this Christmas light explanation!

[@MrKeithsplace]

Awesome demo, just went through this on another’s YT channel, with questions asked. My main question you can probably answer, is how do the “holiday lights” testers work. The ones that some how sends a pulse on the string that indicates the shunted/defective lamp? The one I’m referring to, “Lightkeeper Pro, and now LED keeper also.

[@rty1955]

It uses a peizo elec crystal that gets struck and emits a high voltage momentarily to break down the insulation. Lile a static shock.

[@nathkrupa3463]

My dadpurchased this type series bulbs 💡 on year 2003 wow nice colours 👌you remembered my old days sir thank you so much sir 😊 ❤❤❤ you are really good engineer sir😊😊😊😊

[@MrCarlsonsLab]

Thanks for your kind comment!

[@mouseyou12]

I just want to say without people like you sharing what you know is a gift thank you.

[@denisdespins1127]

I had wondered tremendously for a long time about that Paul. Thanks for for the Christmas treat !

[@MrCarlsonsLab]

My pleasure!

[@buddyfafard8846]

Great demonstration.

[@JMOUC265]

I have an idea for another Christmas tree light video. I switched to LED lights a few years ago on an artificial tree when the difficulty of getting a live tree became too much for me to handle. However, the number of LEDS on the tree is so great that it overwhelms visually the tree’s ornaments at night (too bright). I have been looking for a dimmer controller that would dim the LEDs effectively and without damaging them. Any suggestions or ideas for one? I haven’t found one that is made for strings of LED Christmas lights.

[@JB-fh1bb]

This is a great consumer-level request and unfortunately a complex request when you get to the details of how LED strings work. For example: Some LED strings run directly from 110/220V. Some of those only take the “peaks” of the AC wave, some of them rectify the wave, and some just power the LEDs from the top and bottom of the wave. Some LEDs strings convert AC to DC somewhere after the AC outlet and they could go anywhere from 3V to 24V with multiple different ways of doing that. Of those they could be using constant current or constant voltage to achieve the brightness level. Some LED strings even have circuitry in each LED to allow for better uniformity, longer life, and/or effects. So TL;DR: There are way too many variables to make even a half-dozen “common dimmer devices” and in some cases it’s not even possible without cutting wires.

[@Rev22-21]

It might surprise you to know that they actually make LED strings that are dimmable, but usually they're on the "Pre- Lit" artificial Christmas trees as it were. Typically they have a (or come with) a variable button select box about the size of match box that you simply push the switch button to select 'cool lit', 'natural lit or 'bright' along with optional twinkling and speed control. My wife is using one right now.😅 Merry Christmas.

[@JMOUC265]

@@JB-fh1bb Thank you very kindly for your reply and useful information. I discovered a few of the things you mentioned when I first looked at finding a solution last year. So, I stopped, realizing that I would have to modify my lights and end up worse off.

[@JMOUC265]

@@Rev22-21 Thank you for your helpful reply. I examined my lights last year (they came with the artificial tree we purchased) and I didn’t find anything more than the on-off foot switch. I emailed and called the company where I purchased the tree, but they were not helpful at all, which was a surprise to me at the time. Merry Christmas to you and your family!

[@jeffclark2725]

That explains a lot, your mehod is fully understandable, go home and test out the possible dead strings myself like you did, Thanks for sharing, Thumbs up, great video

[@CliveTrezona]

Thanks for the explanation Paul. If one had some form of current limited supply, the rest of the bulbs shouldn't suffer any further?

[@mistermac56]

Several years ago, I bought several strands of mini LED Christmas tree lights to replace old mini incandescent ones. The strands I bought have a little box that allowed dimming. I haven't had any luck finding any that have the dimmer. Should have bought more when I bought the original ones.

[@elmofeneken4364]

Merry Christmas Mr. Carlson. This was the most interesting Christmas video I've seen this year and I'm not alone because as I'm typing this, I can see the "Thumbs Up" counter increasing.

[@MrCarlsonsLab]

Thanks, and Merry Christmas to you as well!

[@24kJames]

I plainly love your videos. Thank you so much for sharing.

[@FranklinPhan]

Does that shunt have a lower resistance than the filament (after the insulation has been removed)? If so, does that lower resistance allow a higher current flow to the other bulbs? If so, can that higher current flow burn out the other bulbs?

[@TheSimoc]

Yes, it will. Shunted bulb does shorten the life of others and if left so long that second bulb fails and shunts, it doesn't take long for them all to burn out. Have experienced that, and some light strings used to have warnings about this.

[@raveG244]

Love the video, didn't know about the shunt. But, you mentioned a "catch" that shortens the lifespan of the remaining bulbs. Is that because of the lower resistance of the shunt, increasing the voltage/current per individual bulb? My feeling is that once one bulb is out, the others will go sooner.

[@MrCarlsonsLab]

As a bulb fails, it increases the voltage across the others. The more bulbs that fail, the higher the voltage goes across the remaining bulbs. This is why when you spot a dead bulb, you replace it as soon as possible.

[@ianbutler1983]

Yes, the line voltage is divided equally among the bulbs. When one goes and the shunt is activated, that socket is shorted, so there is one less for the line voltage to be divided among, so the voltage applied to each remaining bulb increases. One is not too bad, but if a few go, they start to cascade. That is why when one bulb goes, it should be replaced, even if it is not noticeable. A small increase in voltage can significantly shorten the bulbs life. Long life bulbs are simply 130 volt bulbs. They run slightly left efficiently, but being over-rated by only 5 volts or so, can increase the bulbs life by 5 to 10 times.

[@scose]

Why can't they design the shunt to have the same resistance as the filament?

[@radio-ged4626]

The Christmas light un-fuse. The fuse, in reverse. I like it. I used to put a diode inline with the live lead to give a little twinkle to the light and maybe improve the lifetime of the bulbs.

[@kenromaine2387]

Learned something today about the Christmas tree light bypass function. I had thought the opening of the filament caused one side of the filament support to move making the connection with the wire loop at the based of the two filament supports. (( Like the arm moving on a Grasshopper Fuse. )) Did not understand how the insulation burned of the wire loop to make the new circuit contact. Thank you..!

[@111000100101001]

I love the detail you go into in explaining how the bulb works. A few times I’ve seen a faulty shorting device in a bulb where the bulb flickers and a small arc occurs at the device for a second or two. Then the bulb goes dark as the device has shorted.

[@terrym1065]

Great explanation! Thanks Mr C👍 Merry Christmas to you and yours.

[@MrCarlsonsLab]

Merry Christmas to you and yours as well Terry!

[@Clyde_Lewis]

many thanks for this informative video! I had always wondered about this and how products like the "light keeper pro" would re-activate the light circuit. I have a set of lights in which each bulb has 2 filaments (and the glass is painted 2 different colors, giving the 2 color effect for each bulb, which I love). I wonder if the 2 filament bulbs work the same way? my set hasn't worked in years, and unfortunately, it's hard to find replacements.

[@andysims4906]

These old lights look far better than these lifeless LED type . Hence why I still use sets over 50 years old. I wonder how long this new sets will last

[@johnbellas490]

Who ever thought of that idea to keep the other lights going in the string certainly had a GREAT IDEA with this design, it is a good one!! it was also a nifty idea to use the old capacitor tester to trigger the bypass wire insulation to degrade on cue!! To Mr Carlson I am wishing he and his family has a VERY MERRY CHRISTMAS, and A HAPPY NEW YEAR!!

[@genestatler2514]

Well thanks Paul for enlightening me to what that magic really is. I'd heard that it had a shunt, but didn't know how that worked. All the best to you from Gene in Tennessee.

[@EriksElectronicsWorkbench]

Merry Christmas Paul! Great explanation and demonstration of these seemingly simple bulbs. Recently I have had new light strings totally fail after not much use and I suspect the filaments are not the best quality and the voltage break down of the shunt is not carefully controlled. (just a guess) Older light strings 30 years old still work as they should.

[@MrCarlsonsLab]

Merry Christmas Erik!

[@DarkFlamage]

I was a kid when Mini Lights were a new concept. It was stated on the packaging that each bulb contained a "shunt", (or shunting device) that kept the lights burning even when one or more burned out.

[@lorettacaputo6997]

Thanks for the demonstration and explanation. I always thought it was a bypass circuit in the bulb that kept the other bulbs illuminated. I never knew that it was a fusible switch mechanism. Wonderful innovation, I just wonder if it was applied in any other lighting or power circuitry besides mini bulb strings. I currently have a very long string of lights on my deck railing and just a small portion of a powered string is out that needs investigation and repair. I presume it is now a case of multiple burnouts that made the section die. Investigation will need to wait until I take the string down and have nothing else to do.

[@joverstreet24]

How does the shunt maintain contact? Does it weld itself or is contact simply through tension against filament leads? The shunt almost looks like a tiny spring which would support the tension suggestion.

[@kymlalu]

Yayy, yesterday Fran ( FranLab) had video about same thing.

[@brianredmond4919]

Great - often wondered how that works - question tho - what is that bypass shunt made from ?.

[@AlejandroLopez-qd3xm]

I have noticed the shorting wire on this bulbs without ever realizing IT was 'voltage actuated'! For years thought it was some hi resistance wire in paralell with the filament... it would not have worked that way! 65 years and still learning

[@iamdarkyoshi]

If the antifuse doesn't trip and you do have half a string out, you can remove a bulb from the good half (if it's two series parallel strings) and zap the set with the sparker from a BBQ igniter, and it should make the antifuse trip and short the blown bulb, and the dead half of the string should light when you plug it in again.

[@martinoakley6651]

You mentioned that once a lamp failed and the shunt wire completed the circuit that other lamps would be stressed a bit more. We used to add a dim bulb in series with our holiday light strings to prolong the life. Getting the correct wattage was a bit of an experiment but kept the lights glowing!

[@stephenh.bunkybyrd2024]

Thanks. I learned something about a curiosity.

[@USAMehdi]

Great video, Thanks. What a great invention , so simple yet effective. I want to know who came up with that so I'd shake his hand. lol. Thanks very much for explaining it 👍 I'd have never seen it and it was a mystery until now. ❤

[@betterl8thannvr]

Great use of the capacitor tester, and this answers a long standing question of mine - why I still see continuity on dead bulbs when I check them with the DMM

[@jp040759]

Original approach to explaining this!!! Thumbs Up!!! I was hoping you would show it on a close up closing the circuit on the bulb leads. Expecting a slight spark possibly upon connecting. It is probably not visible though.

[@BjornV78]

These lights bring back memories of my first encounter with mains power. Every few years these Christmas lights strings broke and the supplied spare lights ran out, and a new Christmas light string were purchased, and if they broke, they were repaired with the working lights of the old strings. When I was 5 or 6 years old, I had cut off a socket with 1 light from the old Christmas strings and with short pieces of wire attached to the socket, i stripped the ends of these wires with a scissor,and while holding the green plastic socket,i pushed the 2 wires in the socket (230V). Not knowing that these lights had to be connected in series. The result was sparks and a loud pop, and the light flew a few meters out of the socket. There i stood with that socket between my fingers,the wires still in the socket and my face as white as a ghost :-) I never saw these "self-healing" lights back then (80s), if 1 light broke, the rest no longer worked either. Each new Christmas lights included some spare lights, and 1 light with a bi-metal contact to make the rest of the lights flash at a low speed.

[@lapub.]

A better pop can be achieve by putting a 24V bulb in a 230V socket, the bulb blow very loudly and vanished at the same time, hope to see this in slow-mo one day ! Of course don't do this at home, My father didn't do this intentionally, it's only because we shift to led that he didn't check anymore if the bulb will not glow at 24V before put a new one .

[@BjornV78]

@@lapub. those old incandecent christmas lights are much lower then 24V per bulb. I think they where 50 or 100 lights in series in 1 string, so that is only 2,3V or 4,6V per light bulb at 230V mains voltage here in Belgium.

[@lapub.]

@@BjornV78 2-5 v between each pole of a bulb , but when you touch it, the voltage is from ground, so 0 v at one end and 230 at the other, and just 110 at the middle. for ten bulb in serie you have 24V at each but from ground you'll get 24-48-76-96-120-144-168-192-216-240

[@BjornV78]

@@lapub. yes i'm aware of that, but i cutt 1 bulb with the socket from the string, and was holding the bulb with the green plastic socket between my fingers. I didn't get a electric shock, only the lamp popped and flew a few meters away. But like mentioned, you can may a voltage divider with such a christmas string. Useally, they are 50 or 100 bulbs in 1 string.

[@robertcasey2490]

I've used single or a couple of these bulbs on low voltage supplies. Wondered if the shunt could activate if say the total supply was 6V. According to what you demonstrated, this won't happen if the filament did open on my low voltage circuit. Thanks.

[@mikepxg6406]

Very illuminating.

[@PR-fk5yb]

I have been trying to understand what kept the string ON for years. It was obvious it happened inside the socket but still the magic eluded me. Thanks Mr. Carlson.

[@thevoidedwarranty]

I would've like to know what materials are used & how it was made sure at the manufacturing proceses that it wasn't pre shorted .

[@ThriftyToolShed]

I have known about the shunt in the bulbs for many years, but was unsure of why so many times they don't activate. I wonder if the really cheap light strings if there's enough voltage drop to keep them from shunting properly at times or if typically more than one bulb may fail at the same time in which case the shunts would not work correctly? Nice explainination! Merry Christmas to the Carlson's!

[@JCWise-sf9ww]

You did a much better job at explaining and demonstrating how these lights work when they burn out, than what I seen yesterday on another KZbin channel. 👍🌲🏡

[@1pcfred]

This is starting to feel like a response video. I haven't even seen that other video either. But there's a couple comments mentioning it.

[@JCWise-sf9ww]

FYI: the other channel belongs to a Fran B......

[@1pcfred]

@@JCWise-sf9ww we all know.

[@JCWise-sf9ww]

@@1pcfredThat's fantastic, have a good day

[@1960malcolm1]

I enjoy your videos Paul. Compliments of the season to you.

[@kenrolle2338]

I've pondered that mystery for year's. Thank You for sharing.

[@andrewlittleboy8532]

I only use these kind of lights. I don’t like the LED variants so always stock up on replacement bulbs, luckily they’re still available online. The screw-in style are brighter than the push in type. LED lamps don’t light up the room with a relaxing light like incandescent. I often just have the light from the Christmas lights.

[@Mots-mot]

Create a video on Tube amp and frequency response of left and right channel and calibration of left and right channel (to be identical)

[@Jan_Talcott_100]

I knew they shorted out to keep the lights glowing but didn't know exactly how it worked. Thank you! Merry Christmas.

[@MrCarlsonsLab]

Merry Christmas!

[@sparkyprojects]

If one bulb blows the voltage that should go to it will be shared across the string, if more bulbs blow, the voltage to each of the remaining ones will get too high and cause a runaway short circuit You didn't mention the fuse bulb, which is essetially a normal bulb without the bypass, normally has a white cap, and usually found at the end of the string The scary thing about christmas lights in america is the small gauge wire which will not withstand 16A if there's a serious short, at least in the UK we have fuses in plugs which we can use a 1A or less rating A way i used to make my strings last longer was to get another string and take about 6 bulbs and holders from it to solder into a full string, it reduces the voltage to each bulb, and only slightly noticeable dimming.

[@Truckguy1970]

Actually the ones here do have fused plugs, even the larger c7, c9 and bubble light sets all have fused plugs. In the early 80s Kodak made miniature light sets that had fused plugs along with 2 standard fuse bulbs, the tip was marked green on the fuse bulbs and red on the flasher bulbs

[@donwilbanks2226]

Merry Christmas, Paul! Thank you for the years of instruction and entertainment. AE5DW.

[@MrCarlsonsLab]

Merry Christmas to you as well Don!