When a Light Bulb is better than a Fuse

[@TheColinputer]

I did this on my DIY electric scooter when i was a early teen. Didnt have the money for a variable speed controller so i just had a high current contacter that gave the motor full voltage all the time. After burning out a couple of motors and never managing to find a fuse value that seemed to work the guy at my local electronic store suggested trying some bulbs. Worked a treat. I had some car high beam bulbs that would come on when you turned it on. And slowly get dimmer as you got upto speed. Never burnt out another motor again. And the fuse remained but just for dead short protection.

[@ElectromagneticVideos]

Yet another application for the variable resistance in a incandescent bulb! I never thought there would be so many varied uses. Reading your post I just realized it might have worked for a model train set I had as kid - the engine's motor would often overheat. A bulb might have solved that issue! Thanks for posting.

[@fedgeno]

Yep. A fuse wouldn't have helped, either. They either conduct or blow

[@ElectromagneticVideos]

@@fedgeno After seeing you describe it that way, it I guess they are "digital" - either "on" or (permanently) "off" :)

[@tomschmidt381]

Yup I've used an incandescent bulb as a current limiter since prehistoric days as a kid back in the 1960s. As others have posted it saves on fuses and its brightness gives you an indication of power consumption.

[@filanfyretracker]

so basically if that lamp comes on like it would in a normal light socket in the ceiling, switch it off quick because something is probably shorted or near its release of magic smoke?

[@tomschmidt381]

@@filanfyretracker The lamp limits current so even under most fault conditions no magic smoke is released. Think of the light as a fuse with a rather high resistance.

[@compwiz101]

@@filanfyretracker Yep. So if you have a 60W bulb at 120V, that's a 0.5A limiter. If you had a dead short circuit in your device under test, it would light up like normal but would prevent the current from exceeding that 0.5A

[@nathan.mullin]

I've used basically this setup as a truck mechanic for diagnosing intermittent shorts for years and it's been great. Hook it in place of the fuse and massage the harness and sometimes find the shorts pretty quickly. A bright light is often easier to watch while massaging than a multimeter but the multimeter definitely has its place.

[@ElectromagneticVideos]

There are few things harder to diagnose than something that is intermittent. I don't do much work on my car but I will remember comment if I ever have an intermittent fault. I'll bet your comment will save many people a lot of time and frustration. Thanks for mentioning that!

[@rupe53]

@@ElectromagneticVideos ... this is probably the oldest trick in the book for finding a battery killer. Put a test light between a battery cable and a battery post, then start disconnecting things till the light goes out. Just be aware that certain newer components have a built in residual draw. (ex: memory in the radio)

[@ElectromagneticVideos]

@@rupe53 I'm certainly going to remember that trick! Good point about the residual current - and possibly wiping out all stored stuff like favorite radio stations if the battery is momentarily disconnected.

[@rupe53]

@@ElectromagneticVideos ... it's not that hard to write down the stations and reset the clock, but there's a few other things like the delay timer for the dome light that will throw you a curve ball. Same goes for memory storage in the engine computer, although that will not usually give you full brightness on the bulb. What I do is pull those first to see if I need to do more. BTW, today I changed my battery in the car and used a booster pack to maintain everything during the switch out.

[@ElectromagneticVideos]

@@rupe53 I just looked at your VW restoration channel - what a cool business! The old VW bugs were great - I learned to drive on a VW 411 we had brought back from Germany but never was lucky enough to drive a bug!

[@fredashay]

I have a friend who is an actual electrician. He told me that, back in the days of actual fuse boxes, he would screw light bulbs in the fuse sockets instead of fuses while working on circuits.

[@ElectromagneticVideos]

A while back someone else mentioned a similar thing. I guess it must have been quite common back then.

[@Qui-9]

I was wondering why the fuses used the same base. Maybe that was the reason?

[@ElectromagneticVideos]

@@Qui-9 The base I believe came from Edison light bulbs and I think they just reused it since it was good enough and already in production. I read somewhere in the early days they even used the same base to attach the first electrical appliances. I think it was Hubbell who later invented the first practical plug.

[@johnalexander7490]

@@ElectromagneticVideos One needs to check out all the different Light Sockets in play in the early days. Many differing ones. Is actually quite interesting!

[@ElectromagneticVideos]

@@johnalexander7490 It really is! If your ever in the UK or some for British colonies, look for bulbs with bayonet sockets as a modern day example. Ans also - all the different variants of power plugs we had in the old days.

[@mfx1]

I used to use a firework firing system that used car headlamp bulbs as current limiters in case of an output short circuit (which was fairly common after an igniter had fired).

[@ElectromagneticVideos]

Interesting! I just looked at your Tesla coil videos - did you make the giant ones and somehow modulate them to music? That is incredibly cool!

[@timmack2415]

I'm retired now, but I still restore tube radios as a hobby. If people don't have a Variac, they can start with a low wattage bulb, allowing it to run for a little while and stepping up to higher wattage bulbs as they go. Great video!

[@ElectromagneticVideos]

Glad you liked the video. Good point about starting with lower wattage bulbs. What a neat hobby restoring tube radios. I always liked tube radios and TVs - when I was a kid I started taking them apart for parts and later fixing them. That was the time when they were easily available as people were replacing there old stuff with "modern" solid state radios and TVs. I still have quite a few tube radios from back then - mostly German ones which were always so nicely built.

[@janwesten1317]

At the audiovisual company I worked for, we had a professionally developed test panel with a red indicator light that lit up when a devive was connected wit a short. Later I found out that behind this very small red window was a 150W 220V light bulb. :)

[@ElectromagneticVideos]

Must have been a letdown to discover how simple the technology behind the window was! You sure cant beat simplicity like that!

[@manuelvillanueva3753]

A shorted or leaky bridge rectifier diodes can be detected, also a defective or shorted regulator inducates a bright light... Very useful and effective device...

[@ElectromagneticVideos]

Yes! It really is amazing what all this simple device can help detect and do!

[@nonsuch]

Working on Vacuum Tube gear as I do, it's definitely a must along with a Variac. I ended up buying a case a few years ago of 24, 300W 130V bulbs that should last me for the rest of my life. You can still buy these at hardware stores like Lowes and Home Depot.

[@ElectromagneticVideos]

I'll have to look for them next time I'm at one of those stores. If they don't have them here in Canada (inventory in those store is slightly different from the US) I'll have to remember to pick some up next time I'm in the US. Thanks for posting where you can still get higher wattage bulbs - I dont have any 300W ones. By the way - just subscribed to you channel - when I get a chance I will look at your tube videos!

[@nicklikesradio]

@@ElectromagneticVideos they're halogen now

[@snaj9989]

How are you using them with vacuum tubes. I hace a giant radio vacuum tube waiting to be tested and I would like to know if there are safety measures like that.

[@nonsuch]

​@@snaj9989 You plug in your device under test (your giant radio) into the current limiting dim bulb circuit you create which gets plugged into the AC outlet. This will limit the current through the device depending on the wattage of bulb you use. I recommend no less than 200-300 watts. The bulb will not light up or be extremely dim if there are no shorts. If the bulb lights up bright immediately, you have a short somewhere in the radio. If that happens, unplug it/turn it off and troubleshoot starting with the power cord, then transformer, etc.

[@nonsuch]

@@nicklikesradio No, the 300 watt bulbs I buy are incandescent.

[@martehoudesheldt5885]

they used them in battery chargers for years as a current limiter.

[@ElectromagneticVideos]

Interesting! I didnt know that! I can sure see how they would have been a great in that application before cheap power electronics.

[@jeffkardosjr.3825]

Please explain more!

[@ElectromagneticVideos]

@@jeffkardosjr.3825 If you hook a battery charger to a dead battery you could run into the situation where it appears almost as a short and burns out the charger. Also drawing a lot of current while charging can damage a battery or reduce its long term service life. You could use a resistor to limit the current, but it would drastically show down charging an almost full battery ie when going from 90% to 100%. The great thing about a light bulb is that its resistance changes with temperature. So i in the first situation of an almost dead battery, the large current draw will heat the bulb and make it glow. The high temp will increase its resistance limiting the charging current. At at the battery's charge increases, it will naturally reduce the current drawn, and the bulb will dim and eventually not even be warm enough to give off even a dull light. At that point it will be so cold its almost like a wire and will let the battery get up to 100% nice and fast.

[@martehoudesheldt5885]

@@jeffkardosjr.3825 Automotive chargers from the 50s used them to limit the output current. Some had more than 1. As in 1 for 10 amp, 2 for 20 and so on. I have repaired several for people.

[@REWYRED]

We have and still do wire an incandescent bulb into a standard lighting and receptacle circuit if we have a fault.... Can then go trace the path if the fault current...

[@mr-meek]

Thanks for the description of the non-linear filament resistance. I think you're the first I've come across to mention it, surprisingly. Should have showed the voltage after changing the bulb for completeness =)

[@ElectromagneticVideos]

I think its rarely mentioned because its not the main purpose of a bulb. But its actually a typical characteristic of metals - resistance rises with temperature. Iy has a few common uses - one today is measuring gas flow or air flow and in the mass air flow sensor in cars - two wires have enough enough current flowing though them to heat them. One in placed in the flowing air which cools it, the other is kept in still air. The difference in resistance can be converted to flow rate. And your right - should have showed that. You can do a nice little experiment showing this effect just by heating some wire in flame - will be a future video!

[@Tom_Losh]

Being an old retired Telco tech, many circuits in the old Central Offices had "ballast lamps" (or "resistance lamps") in series with either input or output to protect them.

[@ElectromagneticVideos]

Thats fascinating. So was that on the loop circuits going of to peoples phones? Were they lamps specially made for the purpose?

[@Tom_Losh]

@@ElectromagneticVideos, not so much on the "POTS" loops, but on other circuits that had the potential to put out dangerous or damaging levels of power. DLL units (Dial Long Line signalling range extenders), telegraph, carrier, alarm, etc. They were used on circuits both within and outside the central office. In the Bell System they were made by Western Electric specifically for those different uses, and were sized to fit on standard panel height of 1.75 inch without crowding. Many, many different types and mountings. Here's one: tijil.org/15A-ballast-lamp.jpg

[@ElectromagneticVideos]

@@Tom_Losh I have never heard or seen a bulb like that! How interesting. So if I understand correctly, generally not on the voice but more the signalling pulses? I googled "Dial Long Line signalling range extenders" but was flooded with Wifi range extenders which I dont think are quite the same :) . I'll have to do some searching to see if Northern Electric/Northern Telecom/Nortel made those bulbs up here too. I would love to have seen one of the rooms filled with the old mechanical switch gear in operation. I do have couple of vintage rotary stepper relays (not sure of the correct name) that would have been in one of those switching stations.

[@KenTenTen]

Right. We had them back in the sixties when we had teletype circuits running 120v @ 60ma. Ballast lamp lights up when the circuit gets shorted out somewhere downstream, otherwise it stayed dark. Nowadays, I use a 12v headlight to test 2-way radios in the same circuit.

[@AGB_2000]

@@ElectromagneticVideos Back in the early 90s I worked for AT&T ,Western Electric, as an equipment installer refitting local Bell offices with the new 5ESS switch system which replaced the rotary system with digital. It was always fun checking out the old rotary switching equipment while we installed the new equipment in parallel. Many boring hours spent running wire and testing lines as we went. On the phone lines that I worked on, iirc, the only protection I ever really noticed was the lightning protection on every line coming into the switch, basically a wire wrapped ceramic insulator. One amazing thing was that the 5ESS switch was so small in comparison to the relay banks it replaced!

[@vincentrobinette1507]

Back in the day, I repaired solid state amplifiers. Almost always, they came in with blown fuses, where the customer replaces the fuse, and it immediately blows again. I use this technique, to diagnose bridge rectifiers and power transistors, which almost always fail short. This allows me to apply current to measure across collector/emitter junctions, as well as diode junctions, to tell which device has failed. This apparatus is also a good thing to plug switch mode power supplies (SMPS) into as well. Things like phone chargers and 'laptop' power supplies often use a simple bridge rectifier and capacitor directly on the AC line. These tend to load only the peaks of the AC wave form, resulting in repetitive short duration high current spikes on each crest of the sine wave. Using this as a ballast will reduce the peak current, while increasing the duration greatly reducing stress on the rectifier as well as the capacitor. this type of input circuit is the electrical equivalent of pounding a round peg into a square hole! If you listen carefully you will gear the filament of the light bulb, as it buffers the peak current. It also serves as a 'surge protector', in case a breaker trips, by absorbing the fly back surge, which is a leading cause of SMPS failures. (Size the bulb for ~3-5 volts of drop, for best protection, and best efficiency)

[@BeRight4u]

My inverter fuse aways blows .can we use this technique of bulb .if so how many wats bulb

[@ElectromagneticVideos]

Vincent - sorry I haven't responded to your post sooner. For some reason I dont always see new comments. I really appreciate you taking the time to explain how it can be used with semiconductor equipment. I will have to try listening to the bulb as you describe!

[@vincentrobinette1507]

@@BeRight4u The bulb only helps, if the fuse is blowing because of the inrush current of charging the capacitors, when you first hook up the battery. A lightbulb won't help for a chronic overload condition. If you're blowing fuses during use, check for voltage drop between the batteries and the inverter. Since inverters use pulse width modulation, they will draw more current at a lower voltage, to maintain output voltage into a given load. The more voltage you can maintain on the power input of the inverter, the less current it will draw, and hopefully, stop blowing fuses.

[@BeRight4u]

@@vincentrobinette1507 the inverter design is such a way we can't insert the fuse if it fails.i am looking for a way where i don't have to open the inverter regularly.i don't know where's are problem .any suggestions to solve.

[@LincolnSP150]

In the old homes fuse panels had screw in fuses that were same size as bulbs. Some times when you couldn't find cause for short circuit a bulb was used. When looking for short circuit if the bulb went out, you found the cause of the short circuit.

[@ElectromagneticVideos]

Another neat variation of using a bulb from the old days, although I'll bet its still sometimes done in older houses that have fuse panels (although I'm sure fewer and fewer are left). Thanks so much for mentioning this use!

[@leosbagoftricks3732]

I once saw a circuit using only a lightbulb and some very large inductors and oil capacitors that would oscillate- using the non-linear resistance of the tungsten lamp filament- so cool and fascinating.

[@ElectromagneticVideos]

I have never heard of that - how interesting! Sometime I'll have to see if I can do that!

[@leosbagoftricks3732]

@@ElectromagneticVideos I would start by researching tunnel diode oscillators - very similar concept. The LC tank needs to be resonant at a frequency well below the thermal time constant of the lamp filament.

[@1978garfield]

I remember seeing a vintage train set that controlled the speed of the train by screwing in different wattage bulbs.

[@richardstewart4135]

I am an old time model railroader, but I dont think I have heard of this sort of thing. I can certainly see it used for one of the older AC train sets though. Any idea what make it was?

[@1978garfield]

@@richardstewart4135 No I don't remember the brand. It was owned by Fritz Vantoggen not sure on the spelling. It was featured in one of the TM Lionel DVDs. I will look and see if I can find it online.

[@ElectromagneticVideos]

That neat - probably way cheaper than a variable transformer back then.

[@kittyfanatic1980]

Good explanation of the "poor mans variac" AKA the dim bulb tester. When working with tube equipment especially you start with a low wattage like 15w bulb than go to 25,40, 60,75,100. If at any point the bulb goes bright you have a dead short. This saves both you as well as the equipment under test. Never just plug an unknown condition tube set in the wall from the bat. Especially if its been sitting unused. Always do the dim bulb or a real variac and isolation transformer. May work great may need caps reformed but chances are that youd be in a world of trouble if you fail to properly bring up old equipment.

[@ElectromagneticVideos]

I'm glad you liked it! And very good points and advice for resurrecting or fixing old tube equipment - thanks for commenting. Although I think its actually more than "a poor mans variac" - the great thing about the dim bulb is the limiting current feature - no matter how careful you are at slowly increasing variac voltage, you always have the possibility of a high current short. I have been amazed at how much attention this video has gotten - really shows what a great piece of equipment a dim bulb tester can be.

[@andygozzo72]

@@ElectromagneticVideos i'd consider a bulb limiter far more important, useful, and safer than a variac, have used one for many years, you can also use them as current 'stabilisers' for charging nicad/nimh and lead acid batteries, even direct from mains via a diode if you wish to risk it ! i have an old book that shows accumulator charging from dc mains through a lamp, you would not want to know the 'hair raising' way they said to check mains polarity if you didnt already know it 😲

[@ElectromagneticVideos]

@@andygozzo72 Completely agree! I have never used them for charging a battery but heard stories of what you described. Checking polarity - touch it with your finger like the old electricians used to do?

[@andygozzo72]

@@ElectromagneticVideos actually what the book said was stick the ends of the wires , with a bulb in series with one, in a glass of water with a sprinkle of salt in 😲 the wire that gives off bubbles is negative 😲😲, i've used a small 15w mains bulb plus series diode off the mains for a quick n dirty charger a few times,

[@ElectromagneticVideos]

@@andygozzo72 Practical and simple, but somehow wires + saltwater + 120V seems a bit scary to me!

[@scottthomas3792]

This is an effective old school idea that still has its place.....we used these at my last job, generally with 100 watt clear bulbs. Really simple, but effective.

[@ElectromagneticVideos]

Yes! You cant beat the combination of simplicity and effectiveness!

[@richardstewart4135]

Another great video!! I remember using one of these circuits to test some used equipment (strapping machines) we received to use in a conveyor system . Most of it was exposed to the elements and quite a few pieces would trip the supply breaker when it was turned on. We used light bulbs in series to protect the wiring from the numerous trip loads as we tested the units. These were pig-tails with no power plugs that were normally hard wired into the system. Wire-nutting them to the system through the lightbulbs in series saved a lot of time and prevented damage to the control circuits.

[@ElectromagneticVideos]

Thats another interesting application that I never would have though of. How interesting! Thanks for posting!

[@kylestewart1157]

I ran into a case years ago where a homeowner had his furnace wired with a light bulb as a fuse.

[@ElectromagneticVideos]

Yet another unusual use. I wonder why? In the great ice storm (1997) I tried running an oil furnace off a 1.5kw generator - the startup surge from fan's induction motor was too much for the generator although the smaller burner motor was no problem. I'm surprised it even worked unless he had a really high wattage bulb.

[@power-max]

This trick is commonly used in the RC drone hobby with newly built or rebuilt drones by creating an adapter cable that takes power from a RC battery through a car turn signal bulb to the drone. They call them "smoke stoppers" in the case you had say hooked up polarity of your motor controller backwards or otherwise have a short somewhere.

[@ElectromagneticVideos]

"smoke stoppers" - what a great name! Had no idea drone builders were using them.

[@power-max]

@@ElectromagneticVideos yeah lol. Here is Joshua's video on it! kzbin.info/www/bejne/f2bEYYd3oqqqgqc

[@ElectromagneticVideos]

@@power-max Thanks for posting the link - if anyone is interested in a low voltage version of the bulb current limiter look at the link above!

[@richardhole8429]

I used this regularly in the 60s. It worked well also for reforming electrolytic capacitors

[@ElectromagneticVideos]

Even back then! Yes, great for reforming!

[@thomask4836]

This was very interesting! I have an old Zenith floor radio circa 1940 that I may tackle soon and this was a great refresher. The radio you are using reminds me of the old Grundig Majestic radios. The quality of sound was amazing!

[@ElectromagneticVideos]

The Zenith sure sounds like a collectors item. I would bet there are significantly fewer radios from the pre-WW2 era than from immediately after. Grundig was another fine old German brand. The European radios were so much better built than ours and as you said you can sure hear it. I would bet though that they cost many times the price of Canadian or US ones back then. Glad you liked the video!

[@Sparky-ww5re]

when I was an apprentice about 5 and a half years ago the master electrician I worked under had been in the field for almost 40 years, and when he was teenager back in the 1960s his father taught him how to find a short in the house, with a light bulb. he'd take the wire off the breaker, connect a light bulb socket pigtail to the breaker, then wirenut the circuit wire to the other end of the bulb socket. With experience he was also able to gauge whether the circuit was overloaded and likely to trip a breaker by noting the brightness. with a fuse panel, you can perform the same test, by screwing a bulb in the socket. The younger generation can certainly learn very cool and useful stuff from old gray hair electricians. -)

[@ElectromagneticVideos]

I really enjoy hearing stories like that. I had not heard of putting a bulb between the breaker and the rest of the circuit like that, but a few have mentioned the bulb in the fuse socket. The unfortunate thing is so many people seem to think old tricks like this are bad just because they are old - sometimes the old simple approach is much more practical. Years ago I made a manufacturing tester for product that had a 12V output to drive some auxiliary component. The tester was just a 12V auto blinker bulb soldered onto the plug with a diode in series. The bulb drew enough current to confirm all connections were good, and the diode conformed the polarity was right. I think they still use it today 20 years later.

[@kapilsds7]

I had 10w to 2000w current limiter system made by myself using incandescent and halogen bulbs more than 15 years.

[@ElectromagneticVideos]

Thats a big current limiter! So did you use halogens just because easy availability and small size at higher powers? Or was there some other characteristics that was good for your application?

[@kapilsds7]

@@ElectromagneticVideos I had used halogen tubes for easy availability and cheaper. But most replaced are them. I had eight different power settings with selector switches. 1000w 500w 300w halogens and 200w 100w 60w 25w 10w incandescent bulbs. That current limiter made by myself i'm 14 years old and too much interest in electronics. That saves my time and money and good experience with SMPS and power amplifiers. That idea came for me when technicians using current limiter (they call it load bulb in my country) why i not try to build better one with more current limit settings.

[@ElectromagneticVideos]

@@kapilsds7 Great that you have such an interest in electricity! I'm guessing your not in Canada or the US, so you are probably in a 220/230/240 volt country. Please please please be careful!!!!!!!!! Your voltage has much more of an ability to punch through skin with the slightest surface moisture and deliver a lethal shock or burn than ours does. I know - it happened to me in a 220V country when I was a kid playing in the garden and a hidden live wire touched my leg. I have a huge scar to prove it. Here are some safety suggestions: At a minimum make sure there always is residual current device (RCD) in the circuit but dont rely on it. Or better an isolation transformer. Never be alone in the room or area when working with exposed AC power or more than 24V. You need someone there to help you if something bad happens. They also need to know that they must shut of the power before attempting to help you - AC power can paralyze and disable the helper. And if you have the slightest concern or uncertainly about something, stop, think about it, and get help if needed. These are something everyone should consider, not just young people! We can all get injured if not being careful. Having said all of that, back to your project. Do you really need such high powered lamps? Usually a lamp power of around the power consumption of the device you are testing is a good place to start. That limits the current at maximum what the device would normally draw. If everything goes well double the lamp power once or twice. Typically use 60W, 100W, and 200W bulbs for working on old tube radios. Modern stuff uses even less power. One problem with larger currents is they can sustain an arc quite easily (like an arc welder) and destroy the device you are protecting! I think part of your range 200w 100w 60w 25w 10w would be an excellent current limiter that could be used for most electronics!

[@ronkemperful]

This also brings back memories. My dad, too chicken to deal with the tubes in our television or radio would have me, a nine year old crawl into the cabinet and remove the tubes. We then would go to the grocery store where there was a tube tester with all sorts of plugs and dials, where we could check each tube to find the bad one. Then a couple of bucks later we went home to reassemble the tubes, hopefully fixing the radio or TV. And another memory was an old German made Grundig Hi-Fi that my dad bought while he was in the service. Like your radio it had multiple bands for AM, FM and shortwave. There was a bright green electric eye that showed exactly where the strongest signal for a station was when it narrowed to a sharp line from a fuzzy green circle.

[@ElectromagneticVideos]

Nice story! I'm just old enough to remember the big tube testers that many stores had. I think they began disappearing when I was 5 or 6 years old. I did a lot of TV repairs when I was in high school - had my own tube tester which I got as a surplus kit when presumably the demand for things like that had evaporated. One thing I always remember is some tubes had their part numbers marked with paint that after many years of operation would wipe off when you touched them. And if the part numbers werent shown on the chassis or back or the radio or TV, you were in trouble. I always like the German tube radios and Hi-Fi equipment. It was much more solidly built than stuff made in the US or Canada, and had a higher end feel to them. Every one I have come across had a transformer power supply as opposed to the dangerous direct connected ones made over here. And the eye tubes are great for tuning. I'm sure that added 10% to the cost of the radio.

[@ronkemperful]

@@ElectromagneticVideos The big challenge for us with the German made Grundig was that the numbers and letters on the tubes did not use the same conventions as the American products. So, we had to guess at the correct tube, and somehow we were always right. The large 21" Magnavox television was another issue: while we could fix the tubes for the set's audio, the picture tube was failing and that was well beyond our capabilities to repair. We called out a repairman who said that the replacement black and white tube wasn't made anymore. We were sad, for the TV had great picture and reception. We were the last persons on the block to get a Color TV, for at over 600 dollars they were far too expensive for us to afford in the 1960s.

[@ElectromagneticVideos]

@@ronkemperful I actually got to know German tubes and their numbers quite well - dad was posted to Bonn in Germany in the early 70s so no issues gets tubes withe German numbers. I'll bet the picture tube going doomed many nice sets. $600 back then must have been a fortune. I remember going with dad to buy our first color TV at the US Military PX in Bonn. It had the special ability to switch from European PAL to NTSC so you could take it back to the US or Canada. I actually still have it - will have to do a video about it sometime.

[@ronkemperful]

@@ElectromagneticVideos Will watch out and look forward to your video.

[@ElectromagneticVideos]

@@ronkemperful Great! but dont hold your breath - might be a while till I get to. The other neat thing about that TV is that it has tubes (HV section), transistors (RF) and some IC (Audio if think) which I always though was neat. And the PAL color decoder has an acoustic 1 horizontal line delay line (= acoustic memory). What a combination of technology!

[@Funkybulb]

Nice Dim bulb Tester. Also in older homes with edison base fuse. I screw in the light bulb in the fuse socket so i can Locate the short and clear them before putting a new fuse in.

[@ElectromagneticVideos]

Interesting - I had never heard of that before. There is a lot more to the lowly old incandescent bulb than most people would ever think!

[@hightttech]

@@ElectromagneticVideos: Enjoyed the video. Indeed the incandescent is quite versatile. Besides using them to protect DUT on the bench, I use them to do a quick-test on SLA batteries (usually in the 5-35Ah range). I find that the waveform produced when pulsing a bulb (e.g.12V/75W Halogen) with battery under test reveals much about health of battery. We can usually predict a C20 failure simply from the pulse's FWHM characteristics. Sadly, I have several expensive battery-testers in my lab, and they never agree with one another; even on THE SAME BATTERY. And, results are inconsistent from one battery BRAND to another (e.g. two brands of 20Ah battery that have identical C20 test results might display VASTLY DIFFERENT results with said testers). SUPER ANNOYING. The bulb pulse test gets all the batteries back on a level playing field.

[@ElectromagneticVideos]

@@hightttech Amazing about the battery testers - I assume they are from different manufacturers? Your test reminds me of using a 12V car bulb attached to connector to plug into a power out socket on a piece of electronics we manufactured years ago. It was great way of making sure the connection was good and could deliver an amp or so. A led might have glowed even if there was a few K Ohms in a poor solder joint or some such thing.

[@hightttech]

@@ElectromagneticVideos: Yes; we have several brands of battery testers. I've observed the various battery testers run through their routines with a scope connected. Each has a unique routine, but sadly none ever accurately predict the actual C20 capacity. It's literally all over the board. RIDICULOUS. A real C20 test is the gold standard in our lab for condemning a battery, but the bulb-pulse test is very predictable for quick tests. Also, i agree 100% that loading a circuit is excellent way to verify integrity of current path. Intermittent problems due to failing solder joint(s) or connector(s) will drive techs nuts until one brings out a hungry test light, then naughty spots will reveal themselves with nice voltage drops, and probably glow a bit for a FLIR cam.

[@ElectromagneticVideos]

@@hightttech So I'm curious, what is the application for (trying to) test battery health so accurately?

[@Bristoll170]

Yes, as like a lot of other commentators have said, it's the MOST valuable current limiting bit of test gear. A very simple visual test aid.

[@ElectromagneticVideos]

Yes - so simple yet so effective!

[@123awsomelad]

pretty cool-using a lightbulb as a crude PTC thermistor for inrush limiting (with added visual diagnostics!)

[@ElectromagneticVideos]

Yes! In many ways the visual indication is the best part!

[@Swenser]

Or is it ntc. As current goes through and heats up the resistance goes down acting as a short circuit. Initially the resistance is high. Right?

[@cyndicorinne]

Very clear explanation of how using a light bulb in series helps with running electrical devices while helping to protect against short circult

[@ElectromagneticVideos]

Thanks! I'm glad it was understandable!

[@rickybailey7123]

I love lurning things like this I've got a really out worth some money when I looked it up will try this I didn't know it was bad to just plug it in thank God it worked fine has the bulbs in so cool

[@ElectromagneticVideos]

It is amazing how versatile the old incandescent bulb is!

[@kpdvw]

This radio is designed to work with a external long wire antenna!

[@ElectromagneticVideos]

You are absolutely right - not many people would know that. Its too bad there isnt much of interest on the shortwave bands these days - if there was I would put up a nice long antenna in my yard. Those German tube radios are so nicely made, both in appearance and technology. I have a few others - I will have to do a video about them.

[@RK-kn1ud]

This is exactly why a test light is a far better and safer tool when is comes to automotive electronics as well. DMMs are nearly useless in troubleshooting cars...especially if you know what you're doing. It's just as safe as a DMM if you know what you are doing...and far more informative. Unfortunately it took me about 20 years to realize this. I didn't know what I was missing!

[@ElectromagneticVideos]

Its funny - all the advantages of DMM's high input impedance do sometimes get in the way - I use a 12V bulb to test some power supplies because they need more than a few micro-amps to glow. The old analog passive multimeters are also useful sometimes - they draw a small current but way more than a DMM ...

[@RK-kn1ud]

@@ElectromagneticVideos 95% percent of automotive diag work is simply checking for power/ground. About 4% is verifying that circuit can actually carry current. Both of these are much quicker to test with a light bulb. The other 1% of automotive diag can only be verified with an oscilloscope. Sometimes a DMM is useful in voltage drop testing if you can't load-test a circuit. It's also useful in checking to see if the alternator is charging the battery I suppose. Many places will try to ban test lights mostly because young players don't know HOW to effectively use one. I will say that most automotive circuity is pretty robust...and can usually handle a bit more abuse than your standard micro-controller.

[@ElectromagneticVideos]

@@RK-kn1ud Wow - trange that they would bad such an effective tool rather that teach them how to use it. I have always been impressed by ruggedness of automotive electronics - its an absolutely terrible environment from the standpoint of heat, vibration, and corrosive chemicals - and yet is so reliable in most cases. I have done vibration testing of equipment for aeronautical applications - much less vibration than a car on a dirt road - its amazing how wires or other things that rub against each other get destroyed in relatively few hours when exposed to vibration.

[@mnshp7548]

using a kettle works well too, in the uk, you can get 3200 ish watt out the plugs, any more and your breakers or fuses blow, if you get a 3000w heater or kettle, you can put it in series then short it out all day as your current limit is 3000w, same with a small 300w heater, just be careful in remembering what becomes live and neutral

[@xtv007]

Analog soft start device. Neat.

[@brianjonesg8aso403]

I used to work in a telephone exchange that all ran on 50 volts, it was standard practice to use a buld instead of a fuse to help locate temporary faults in the Strowger equipment. If you used a fuse, every time an intermittent fault appeared a whole section of equipment would be out of service causing all kinds of problems and alarms, with the bulb, when a fault occurred, it would just light up so we could investigate, and when the faukt went away, everything would work again. 1970s.

[@ElectromagneticVideos]

I have always wondered how hard it was to troubleshoot those rooms of mechanical switchgear. I'm guessing you had tools to clean or tweak slightly bent contacts, but finding which contact in which switch? I would love to have seen one of those mechanical exchanges in operation. When I was in university, the small city it was located in still had mechanical phone exchange and I think they may have started to skimp on maintenance since they knew it would be replaced soon. Sometime you would get a really bad phone connection - noisy etc and the solution was to hang up and try again and hopefully get a different set of switches. When it was converted to an all digital presumably Northern Telecom switch the improvement in quality was noticeable!

[@mlpabq1]

The Bell System used bulbs instead of fuses in all kinds of switching equipment back in the day

[@ElectromagneticVideos]

Someone else mentioned that - I had never heard that before. I guess is was cheap and effective!

[@spelunkerd]

We use the same kind of devices for diagnostics in the DC world. In the case of a dead short, the bulb offers enough resistance to prevent the fuse from blowing, allowing one to do wiggle tests and current tests to try and isolate the short.

[@fredsalter1915]

Good video! Shoulda demonstrated a ground fault by "jumping" the unused plug with a bare wire. Cheers!

[@ElectromagneticVideos]

I guess i should have though of that :) Just looked at your video of the giant chromatography machines - would be great to if you did one about what you separate or analyze with them - I'd sure watch it!

[@LenweSaralonde]

The most difficult nowadays is to find incandescent bulbs.

[@ElectromagneticVideos]

So true! Depending on where you are, dollar or discount stores sometimes have them. Commenters have reported using halogen with good results but I haven't had a change to try them myself.

[@ttnyny]

Thanks. How does this compare / contrast with a variac and why do most repairers seem to use both a light bulb and a variac when energizing old equipment for the first time?

[@ElectromagneticVideos]

A variac provides adjustable voltage at almost limitless current (limitless until its fuse blows). So if there is a short/intermittent short/low resistance fault in the device you are testing, even if you are really careful bringing the voltage up slowly you may end up damaging some components around the failed one with too much current. Or the variac or device's fuse pops before you can tell what part is shorting. The bulb limits the current hopefully to a low enough value that hopefully other components other than the failed one wont get damaged. And with some current flowing you can often use a voltmeter to find where the short is quite easily. The current limiting aspect can also be used to reform capacitors in old electronics. The use of both is give a bit finer control than is possible by switching bulbs ans also the ability so gentry raise the voltage while having the protection of current limiting. So the best of both devices.

[@tfin-ch7ql]

I’ve got them in my mackie art300p as an overload protection. they are Megga un efficient but sound great

[@ElectromagneticVideos]

I'd heard of people using them with loudspeakers - what a great application!

[@crazychicken2005]

i came in wanting to see a light bulb used as a fuse, i cane out knowing a lot more about tube radios, and just picked one up for myself, although it did not have any problems and worked with no issues, i still think it is cool to see it working. its a very small emerson radio if anyone is wondering

[@ElectromagneticVideos]

You must have read some of the comments - there have been some absolutely fascinating discussions which I was not expecting for this simple little video. So cool that you bought a tube radio. Do you know the model number? You said it is very small so it might be an All American Five type radio. See en.wikipedia.org/wiki/All_American_Five unless its battery operated.

[@besanit]

I alway had a very foggy understanding of this trick, thank you for taking the time to explain this.

[@ElectromagneticVideos]

I glad you found it interesting! I find it neat how an old simple bulb can be so useful. There are some really interesting stories of similar uses of a bulb including in the old phone system switching station that people have told in the comments.

[@d46512]

Another great video. When I assembled my isolation transformer from Digikey I placed a DPDT switch in the box between two outlets. The switch is wired so that I can quickly put a nice big lamp in series with the load. My only concern now is finding incandescent bulbs. I just realized Ontario has almost completely banned T8 fluorescent lights, probably the cheapest, most reliable and long-lasting lighting technology mankind has ever known, not to mention an install base which is no doubt in the tens of millions in this country alone.

[@ElectromagneticVideos]

Thats convienient. You still seem to be able to get incandescents alhough I did hoard a bunch when Rona got bought by lowes and had a huge clearance sale. I didnt realize T8s were actually banned. I had good luck with a bunch of T8 LED replacements I also got for cheap from Rona's clearance. Interestingly 2/3 the power and a scalled down light output partially compensated for light production in one direction. Would not be great for outdoor signs needing light on both sides.

[@d46512]

@@ElectromagneticVideos Two thirds the power is nice but not compelling enough to justify the cost and reliability of LEDs. I think this ban was targetting the small amount of Hg in the tube. Even if ballasted fixtures are still okay, it makes no sense to choose them in new installs. Time will tell what type of "native" LED installation is best.

[@ElectromagneticVideos]

@@d46512 Completly agree - many toxic inly reason I went for them is I got them for $3 each. You also wonder how many toxic chemicals from semiconductor manufacturing compares to the Hg in terms of impact.

[@tableseven8133]

I might make one of these for my O gauge train setup. However most transformers will be 90 to 300 watts so I don't know if a 100 or 200 wat light bulb will make them work well. My thought was if there is a short; instead of depending on the built in circuit breaker, if it has one, the short will just make the light bulb glow brightly, instead of maybe melting a wire, or causing more arcing on the track. Something to try some time.

[@ElectromagneticVideos]

It might work. The neat thing is that when the bulb is almost unlit, the resistance of the filament is way down. I would try a bulb close to the rated watts of the transformer or a bit more. So for a 90W transformer, maybe a 100W or 150W bulb. Maybe even 200W. For larger transformers, you may need to parallel a number of bulbs. Probably best to use identical ones so their heating profile is the same. You could also try a bulb on the low voltage side is you can find a suitable one - perhaps a 12V car bulb might work .....

[@peterpb0ans68]

Good idea. I’ve got one for years now, to start up old stuff safe…

[@ElectromagneticVideos]

That what I use it for. Can also be used while old electrolytics re-form.

[@timteecvhn]

Reminds me of the isolation transformer that Mr Carlson's Lab has for working on older equipment. As I believe it has 2 bulbs, I forget, but he does use bulbs too to limit current, alongside a transformer to provide an isolated line that isn't directly connected to mains and whatnot if i remember right. (also has the benefit of being able to slowly bring up the voltage and bypass the bulbs when the radio has been slowly warmed up and whatnot so it doesn't just, immediately blow up when plugged in.)

[@ElectromagneticVideos]

So a more elaborate combined unit. Neat. It is worth pointing out (and I don't recall if I did it in the video) the bulb(s) protect the device, not the human. An isolation transformer protects the human, less so the device. The combination is what you need to more safely troubleshoot something. Of course its still possible to get a dangerous shock if you touch two location in the device under test and one has high voltage.

[@ssikhcnerf]

@@ElectromagneticVideos An isolation transformer only protects you relative to earth... if you take the output wires of your isolation transformer in both your hands your chances to die are higher than if you put your hands on the mains...

[@ElectromagneticVideos]

@@ssikhcnerf Your right about it not protecting you if you touch two areas of different voltage on the isolated side. As far as it being worse than touching the mains wires, that depends entirely on what you touch and how you touch - surface area on your hands, voltage (say on a tube radio or tv) etc. Even then it would be no more dangerous than if the device were plugged in without an isolation transformer.

[@gideonlapidus8996]

As an apprentice used to use this as a series test leads for electrical continuity

[@ElectromagneticVideos]

With 120V? Or did you use a lower voltage for the bulb?

[@gideonlapidus8996]

@@ElectromagneticVideos 230v in South Africa

[@JayEllis76]

I have a 67 Dodge truck that has one of these blocks, but it has a lightbulb-style fuse in it

[@ElectromagneticVideos]

An antique!

[@connectionlost1063]

The Fpv drone community utilise this principle quite often and they call em smoke stoppers lol

[@ElectromagneticVideos]

I just saw a similar comment - I had never heard the name "smoke stoppers" but it is perfect!

[@GrowlyBear917]

I put an incandescent light bulb in series with a Compact Fluorescent Light, and used it for a long time. The CFL ran at full brightness, until one day it failed and the other bulb came on. This indicated that when a CFL goes bad, it shorts, then blows an internal fuse. But since the short circuit current was limited by the 100-watt bulb in series, the fuse didn't blow, the CFL just stayed shorted. Also, you can't buy a 100 watt bulb around here any longer. I have a pack of unused ones, maybe I can get rich quick.

[@ElectromagneticVideos]

What an odd failure mode! Was it electronic ballast or the ones with an inductor and the flicker switch? Would be interesting to know if that type of bulb always fails that way or what you observed was a rare occurrence. I have occasionally seen incandescent bulbs at dollar stores, so your stash of them might not be a cash windfall - yet :)

[@rupe53]

@@ElectromagneticVideos ... yes, dollar stores (old stock) or garage sales.

[@ElectromagneticVideos]

@@rupe53 Someone recently mentioned in on of the other comment threads threads that Lowes in the US still sells 300W incandescent. Next time in in the US I will look. I'm sure a suitcase full of bulbs will give the baggage X-Ray people something to scratch their head over :)

[@rupe53]

@@ElectromagneticVideos .... anything to declare sir? BTW, the manufacture of bulbs over 60 watts is slowly being phased out. You can still buy "appliance bulbs" which will work in high or low temps. (oven / fridge) Obviously the electronics for LEDs or CFLs can't withstand extremes.

[@ElectromagneticVideos]

@@rupe53 And if the customs officers are young they may never have seen an old style light bulb :) Actually they are pretty good at dealing with a suitcase full of weird electronics as you declare it - I'm sure they have seen stuff beyond anything we can imagine after doing the job for only a few months :) I have found most LEDs are fine in cold temps outside (-30C nights) or in the fridge in case anyone is interested.

[@MottyGlix]

Why didn't you give us the final supply voltage with the second bulb, the way you did with the first? That was a piece of information that I needed.

[@thebush6077]

Love the idea that they marked out all the various cities on the thing rather than just printing a list of cities/stations with the frequency to tune to

[@ElectromagneticVideos]

It is neat - seemed common on European radios of that time period. I wonder if it was because the were all generally fairly close together geographically and it made it more practical than the more scattered and further apart stations sin North America.

[@MichaelVx]

me and my family many many years ago until now use this while fixing TVs and other stuff that need safe test before it go into direct power to make sure it will not cast fire or anything

[@ElectromagneticVideos]

You cant beat a simple dim bulb for things like that!

[@no-damn-alias]

We did this to control charge current and voltage on batteries with a self made power supply with different settings.

[@ElectromagneticVideos]

I can see how it would be a good current regulator for batteries. What a great use.

[@nudebaboon4874]

This is the second video of yours I've watched, excellent stuff well explained, hope KZbin continues to push your stuff you deserve a lot more subscribers, many thanks.👍

[@ElectromagneticVideos]

Thank you so much - I really appreciate it!

[@opera5714]

EICO in the early 60's had an ad for an amplifier kit and it said all you needed to test it was a lamp. I've used one ever since repairing electronics. Back then fuses were cheap. Yikes what they cost now.

[@ElectromagneticVideos]

EICO - haven't heard that name for years. I think my old tube tester built from a kit that I got from a surplus place was EICO!

[@SirFrag32]

Basically it's a big resistor. We use this in the RC hobby (10 watt automotive bulbs) to protect new builds from a short-circuit the first time you power them up off a lipo.

[@copescale9599]

I have seen a guy on you tube who uses one of these, works on vintage guitar amplifiers and hot rods. Uncle Doug

[@ElectromagneticVideos]

I'll bet they are tube amps - would be perfect for that!

[@copescale9599]

@@ElectromagneticVideos yes high dollar pieces from as far back as the 30's

[@ElectromagneticVideos]

@@copescale9599 I remember reading somewhere that people strip tube amps out of old Bell and Howell movie projectors for the purpose. Interesting how amps from that far back apparently are so good for modern guitars.

[@mr-meek]

Uncle Doug is great. Highly recommended to anyone interested in tube audio

[@mr-meek]

​@@ElectromagneticVideos We also strip them out of vintage organs, radios, and televisions ;-) The best part about about tubes in guitar equipment is the characteristic distortion. Transistors more or less sound terrible when overdriven (except arguably germanium), but, tubes have a nice warm sort of softness despite still being gritty. There are some hybrids (and effects units) that use tubes in the pre before a MOSFET power section, which works to an extent, but the sought after sound comes from cranking it to 11 and overdriving the entire signal chain. It's really unmistakeable when you've heard and seen a face to face comparison on a scope. Some argue tube audio is warmer in general; I interpret that is due to a roll off on the highs due to poor response in the upper frequency range. Personally prefer solid state for clean tone, but, I'm a 90s kid so I like the sterile 16bit 44khz hi-fi sounds I grew up with on optical discs... "warm" clean tones need not apply, lol. Everything is digital modeling now anyway. Computer manipulated sounds are surprisingly as good or better than tubes in many scenarios

[@inlandbott]

great video! i’m a bit confused on the difference between using this or a variac. this limits current, right. and the variac limits voltage. i assume u can use them in series? variac and then dim bulb tester?

[@ElectromagneticVideos]

Yes - you described it well. But just to be clear, when you limit the current with a device like this and the load (radio, tv or whatever you are working on) starts drawing current, the voltage will drop so you may have to put in bigger bulb to increase the current and bring the voltage up for the device to begin operating. Its usually the current that causes things to melt to catch fire so limiting the current usually prevents that. If you use a variac by itself and have a short somewhere, it can supply enough current even at low voltage to do some damage. So whether you use a variac or bulb or both depends on what you are working on.

[@inlandbott]

@@ElectromagneticVideos gotcha .thanks for the quick reply! cheers!

[@DobbysHobbies]

After hanging out with my grandfather I can say whole heartedly I know exactly what your shop area probably smells like.

[@ElectromagneticVideos]

The sawdust and cut wood smell? I smell that sometimes after cutting some new wood and that immediately reminds me of my childhood and the lumber place dad and I would go to get wood.

[@ve2um]

I still use it today (along with an isolation transformer) to work on SMPS... VERY useful !!! For convenience, i use double-ended halogen light bulbs (protected in a metal case) that can be rated up to 500 Watts.

[@ElectromagneticVideos]

Yeah - you cant beat the simplicity and effectiveness of a simple incandescent bulb. Someone else mentioned halogens. No issues with the bulb operating at lower temperatures and halogen cycle not properly re-depositing the tungsten? I once tried using a halogen as a load for testing a solar panel setup and the DC seemed to mess up the halogen cycle at one end of the bulb and it burned out quickly.

[@Dicofol1]

Can we use an incandescent halogen bulbs ? How come the higher the bulb wattage, the less resistance there is? How do you select the proper initial bulb wattage?

[@hightttech]

1. Halogen is fine. 2. Ohms law. 3. Start small, especially if DUT status is unknown or known to be blowing fuses. If the bulb causes too much voltage drop for DUT to operate, you can increase buld Wattage to reduce voltage drop to DUT. Again, Ohms law is your friend, understanding a little about resistor dividers helps, and playing with KNOWN GOOD devices at first will help you understand how to use this awesome setup. Cheers

[@ElectromagneticVideos]

The lower the resistance, the more current flows. voltage x more current= more power.

[@ElectromagneticVideos]

I wonder if there is voltage level for halogens where the glass temp is not sufficient for vaporize - redeposit cycle to work. Or if when the temp is that low, the filament is fine because it doesnt loose any material?

[@hightttech]

@@ElectromagneticVideos: For what it's worth, I have Halogens that have been around the bench for YEARS. I like halogen due to high current in smaller packages. I have 500W and 1000W theatre spotlight bulbs which are short lived in their native habitat, but living comfortably in my lab. Life expectancy when repurposed as test gear hasn't been an issue.

[@ElectromagneticVideos]

@@hightttech So no issues when operated at lower power - interesting. I tried one as a solar panel load. The DC seemed to kill it - I think it caused the re-deposition of filament material to be more towards one of the ends.

[@onmyworkbench7000]

Back in the early 1970's when I was in the 9th grade I had a science teacher that told me anytime you are powering up old electronics with electrolytic capacitors that you should power them on for a second or two and power them off and do this a dozen times or so and then do it gain and a gain for longer and longer periods of time limits the current on the electrolytic capacitors and gives them time to recover. I don't know it it worked but I never had an electrolytic capacitor blowup on me.

[@ElectromagneticVideos]

Smart teacher! And that advice sounds like it worked for you! They do degrade without use over time and you need to reform them to restore the oxide layer. A gradually increasing voltage or a few power cycles as you describe will do it if they haven't lost too much moisture. Funnily enough, I had one spew steam on me a few days ago after powering up a 5 year old solar inverter that was unused but brand new. Unfortunately it was such a microcontroller managed device with many caps that it was hard to tell if a particular cap was being charged or not. I have a replacement cap on the way ....

[@sparkyy0007]

Saved me many flyback transistors...

[@ElectromagneticVideos]

Way easier to fail than good old tubes driving flybacks!

[@sparkyy0007]

@@ElectromagneticVideos Ahh tubes, when life was easy...and profitable.

[@ElectromagneticVideos]

@@sparkyy0007 You might like my old tube flyback then! kzbin.info/www/bejne/Z3SthJekZc9kZqM

[@jamesalles139]

yes indeed! with a 12v bulb, this can be used for automotive troubleshooting as well. *subscribed*

[@ElectromagneticVideos]

Ill have to remember that - never thought of it for cars.

[@vincentrobinette1507]

A 12 volt bulb is a good way to pre-charge the input capacitors of DC/AC power inverters, and large car audio amplifiers. It's the perfect protection if (heaven forbid) you connect the supply backwards. If the bulb stays lit, you know the polarity is wrong, and with the ballast of the bulb, there likely won't be any damage. It can save a lot of money$$$

[@ElectromagneticVideos]

@@vincentrobinette1507 What a great idea. I always dislike the big spark when attaching a big inverter and with the bonus of catching a disastrous error this is great.

[@jamesalles139]

@@vincentrobinette1507 yes, I have a SPST switch circuit for pre-charge & discharge. The polarity protection part is genius, thanks! (I have only blown up a yard-sale inverter ;)

[@szki272]

I have done similar in 12-volt wiring testing. Sometimes I need to power something and don't know what wire is which. Often both sides will show as ground. The light will light up before frying the circuit.

[@offgridnzdotcom1027]

awesome tool to have in the kit

[@UltraMagaFan]

Just a friendly tip you should say the individual letters when you say led bulb. I thought you said lead bulb and I was so confused. Other than that this was a pretty interesting video. I enjoyed it.

[@ElectromagneticVideos]

I appreciate your friendly comment :) I guess I say it the way I do from electronics work in a similar way fet, mosfet etc is pronounced. Your not the only one who has commented about pronunciation! Glad you liked the video. I'm amazed at the interest this video has generated and the similar uses for incandescent bulbs people have mentioned (well worth reading the comments if you haven't!)

[@revoxjazz8317]

Two questions: First: I'm in Europe (Portugal) and our voltage is - officially - 230 volts. Is it possible to make this circuit for 230 volts and expect it to effectively protect any equipment that works at 230 volts? Second: As it is already difficult to find this type of lamp, can I use a PAR 56 (Halogen type, 230 volt, 300 Watt)? Tanks in advance. Macedo Pinto Portugal

[@ElectromagneticVideos]

It should work with 230V as long as the bulb is 230V. You typically need to somewhat match the lamp wattage to the wattage of the device you are testing. So for a 50 W device a 300 W bulb may give it close to the full 230V. So you typically start with a lower power bulb like the old 60W ones which would really limit the current and then 100W and them 150W etc. Someone said halogens will work, so try it. Over here some specialty lamp stores sell all sizes of the old style bulbs, so maybe there is a store like that in Europe. With your voltage twice as high as ours, your risk of serious shock is higher. I hope you will consider using a ground fault interrupter (residual-current device) or isolation transformer for any testing you do. Great to hear from someone in Portugal!

[@revoxjazz8317]

You can't imagine how grateful I am for your clear and concise explanation on this matter that I think is of the utmost importance. My question was whether it would work under our voltage, 230 volts. I have now fully understood the issue of assigning the different wattages of lamps to obtain the desired protection, in particular the reason for matching the consumption of the equipment to be tested and the consumption of the lamp, which should be as identical as possible. Once again, thank you very much for the explanation. I wish you health and good work! Be safe!📻

[@davidfalconer8913]

Used this trick for decades ( ! ) ..... also useful when using very high voltage transformers with gas discharge tubes , which draw more current the hotter they get ( negative resistance ) .... but much more useful when trying to work out the connections to a ( valuable ! ) but unmarked transformer , connect mains to a 12 Volt winding , just results in a bright lightbulb ! ! FYI in the UK we can still buy these bulbs marked ( rough service ) and also Poundland™ sell antique style tungsten filament bulbs ( 60 Watt ) for £2 ... you might get these in your Dollar store™ , but it has been many years since I visited the USA , so you will have to check this out yourself ! ! ..... ( ? ) .........

[@wolu9456]

kzbin.infoS8ye7U8-78E cooler irl

[@marmaly]

Lead bulbs? Who says that?

[@jimfindley1004]

Dc as in direct current? I was under the impression that most if not all countries used ac or alternating current

[@ElectromagneticVideos]

What did I say about DC? I might have misspoke!

[@ketas]

in the background it seems to be bigclive's favorite cliff quicktest?

[@ElectromagneticVideos]

It is a Quicktest! I have seen it on Big Clive! So few people know about that fantastic device particular here in Canada and the US - they even make it with our hot and neutral colors. I actually did a video on it way back.

[@mr-meek]

@@ElectromagneticVideos I've been watching Big Clive use it for years and had no idea they made them for 120v. I'll have to seek one out

[@ElectromagneticVideos]

@@mr-meek www.newark.com/ has them (all versions so make sure you get the 120V one). Also show up on ebay and amazon. There not cheap - generally a bit under $100 last time I looked - well worth it though!

[@mikewalters5653]

Events of my day today were I guess the word may be serendipitous. I’ve been watching some of James Condon’s videos lately so I went out and bought a Kill A Watt monitor and a digital clamp meter and changed the dead battery in my old Sears digital multimeter. I was using the Kill A Watt this morning to see what the wattage was on a small Sunbeam electric “cube” heater to see if it would draw enough power to be useful in testing my 3000 watt home generator ala James Condon. (Also have a 1500 watt heater like James uses.) I noticed that with the heater on the high setting and the thermostat turned all the way up the watts were about 800 and slowly climbed to 1000 and stabilized there. I was wondering why the 200 watt climb happened and concluded that as a resistor coil heats the resistance must increase. Then I googled why you should not plug an electric heater into a power strip/surge protector which I recently read somewhere since I’ve been doing that for years. This led me to your KZbin video about overloading extension cords and below that was this video about the light bulb protecting electrical components and that reminded me of videos I used to watch about amplifier repair by Uncle Doug I think it was. In this video you talk about how as the bulb filament heats it takes or draws more load or something like that and this confirmed my observation that as my small heater heated up the watts climbed by 200. When you turned on the vintage radio I was disappointed when it did not immediately blare German martial music, hah hah!

[@ElectromagneticVideos]

You just gave me the greatest laugh about blaring German martial music - I wish I had thought of that! Very interesting observation about the heater - it really should have gone the other way. Heat makes metals more resistive so as they heat up, the heater element should draw less current and therefor less power. Maybe the fan was slow to speed up and cool the heater elements so their operating temperature dropped as the power consumed increased?

[@mikewalters5653]

OK, thanks for replying and setting me straight on my incorrect thinking about heat and resistance and what this does to the power usage. The problem may be that the heater coil is badly clogged with dust and the fan cannot blow much air through it. I’ll take it to a relative’s house that has a large air compressor and attempt to blow the dust out from the fan (back) side. I took it apart and tried to clean the heater coil from the front side with a “dust buster” vac but that did not help very much. I’ll try that experiment again with a hair dryer and see how it goes. Thanks again for replying and thanks for your interesting and informative videos. I’m looking forward to learning more about electricity and maybe I won’t shock myself like the great inventor and musician Les Paul did to himself. I think I read it took him almost two years to recover!

[@ElectromagneticVideos]

@@mikewalters5653 Well you had the right idea as to the heat causing the change in power. If it clogged, who knows what happened as it heated up - maybe some of the dirt blew away or melted allowing more air in. Be interesting to see if you can see any such effect with the hair dryer. I had never heard of the Les Paul shock story - just googled it - he must have suffered extensive skin burns form the sounds of it - how terrible that must have been. Glad you enjoying my videos. Don't hesitate to ask questions - I'm always happy to try and explain things that maybe weren't as clear as they should have been in the video!

[@jjmcrosbie]

Yes, good practice for certain applications - not all. 1 - For example, the inrush current of a 100W lamp might exceed 10A, so it doesn't replace a fuse for all applications. Of course, even fuses - all fuses - have a time constant. This is expressed as the time to rupture expressed as a value of I²t. The useful characteristic of the lamp is of course that when you're testing a low current circuit, the lamp will drop only a small voltage if the circuit under test isn't taking overcurrent (or even s/cct), whereas it exerts its own current limit under fault conditions in the cct under test. Which is very convenient. 2 - The characteristic of a tungsten lamp can be approximated to the square-law parabola which passes from 0A,0V to the point (rated I), (rated V) and then just pull the bottom of the curve to allow for the cold resistance of the filament. But that's only necessary if the characteristic is to be part of a circuit. 3 - In fact, before low power solid state thermistors were available, low power tungsten lamps were used as the series element in negative feedback loops as a means to provide a measure of output voltage regulation, especially in valve (tube) audio oscillators. This used exactly the same principle as explained here and in the video. 4 - Of course the valve circuits operated at sufficient voltage and power to drive a small lamp. For those wishing to experiment with lamps in NFB networks in much lower power semiconductor circuits, lamps can be found as low as 6V/40ma in standard "Lilliput" format or even 1.5V'/15mA made for watches. A point to watch here would be the thermal time constant of the lamp chosen which reduces as the rating of the lamp reduces, but remains significant in electronic circuits.

[@ElectromagneticVideos]

Thanks for the extensive comment! I'm sure readers will find it very useful! Are you from the UK? I noticed your use of "valve" ...

[@jjmcrosbie]

@@ElectromagneticVideos Thank you for your reply. Yes, I'm from the UK. Chartered electrical and electronic engineer, retired, aged 81. Seen it all. I've edited out an error in my reply: that should be "parallel element" and not "series element" in (3).

[@ElectromagneticVideos]

@@jjmcrosbie That neat! "Chartered" - I'm assuming that means licensed? I am the same - here (Ontario, Canada) the designation for licensed is "P. Eng = Professional Engineer" although most of the general public has no idea what it means.

[@jjmcrosbie]

@@ElectromagneticVideos From link: en.wikipedia.org/wiki/Chartered_Engineer_(UK) In the United Kingdom, a Chartered Engineer (CEng) is an engineer registered with the UK's regulatory body for the engineering profession, the Engineering Council. Chartered Engineers are degree-qualified or can demonstrate equivalent work-based learning and have gained the appropriate professional competencies through education and working experience. One has the title Member of the Institute of (type) Engineers. My type was "Electrical" so I was an M.I.E.E which embraces both heavy electrical engineering (heavy machinery, generation, distribution and Lighting) and electronics. Originally I had both qualifications, electronic (Institute of Radio and Electronic engineers) and electrical (Institute of Electrical Engineers) but then the latter absorbed the former, reducing me to a single qualification. No problem. Incidentally, on leaving employment in the profession (in my case enforced early retirement) you loose chartered status, although it's still there if you resume work in the profession. You can however apply for your institute's diploma, in my case Dip. EE. Incidentally, members of the Institution of Civil Engineers have the title M.I.C.E. That's why they repair road dents. (Eh?)

[@ElectromagneticVideos]

@@jjmcrosbie Interesting - so its similar but also a bit different here - in the professional designation we don't include the type of engineer - we all just have P.Eng. after our name. To get that you need a BSc or BEng in an accredited degree program, then take a number of non technical tests (ethics and law/rules) and have to show a number of years experience working under a license holder. If you don't have a degree from an accredited university you can take a series of technical exams. We are required to do a certain amount of continuing education/learning every year and have to indicate the ares we practice in - in my case electrical (which includes electronics), computer and physics. You could probably guess those from my videos. So in your case the Dip EE is available after you retire? Or can you apply for it at any time?

[@meberg500]

Where can I find one of those lead bulbs that "completely replaced ◔_◔" incandescent?

[@ElectromagneticVideos]

:)

[@michaelsegal3558]

8:14 he is holding the voltage meter in a way where the reflection of the light is blocking out the display to the camera

[@WompWompIndustries]

I remember someone fixing our pool garage door he used a lightbulb and the bulb lighted up and the garage door still wasnt working i think it was a mechanical problem with the garage opener and closer itself

[@ElectromagneticVideos]

I would guess in a system like that where you have the controls and actual door opener quite far apart would be very useful to isolate the problem.

[@Curiosity_Cars]

carlson labs use lightbulbs also

[@ElectromagneticVideos]

I'm not surprised - he does great stuff with vintage equipment!

[@TimJohns]

I am henceforth going to annoy my kids by referring to incandescent bulbs as "current-actuated temperature modulated variable resistors". I repaired solid state electronic equipment for a local music store in college, and this would have come in handy at least once. The store's circuit breaker served a similar purpose, but turns out my test bench was on the same circuit as the point-of-sale system, so was a little less convenient for that reason (as well as requiring a full 1800w of draw before tripping, so didn't always protect everything...).

[@mr-meek]

I'm permanently borrowing "current-actuated temperature modulated variable resistors" 🤣

[@jagmarc]

Electric heater drops less voltage than a regular light bulb- if it's problem affecting the equipment working properly. But best of both worlds is a find hefty light bulb, say 400 W halogen. Its cold resistance doesn't affect the circuit as much... until there's an overload and then the lamp resistance increases. Of course it limits the maximum current to whatever that light bulb uses.

[@xntumrfo9ivrnwf]

I have that same radio!

[@ElectromagneticVideos]

Neat - the vintage German Radio are so nice!

[@thomasdavis4253]

It along with an isolation transformer and a variac, is a good way to slowly bring up older equipment to test it, but if you have the slightest care for the equipment, beyond just testing and troubleshooting, I would not trust older electrolytic or paper capacitors to simply "reforming" at limited current. While they may appear to be working, they can be passing DC and the result can be blown tubes and/or transformers, some of which are unobtanium these days.

[@ElectromagneticVideos]

Very good point! And unfortunately theses days, due to supply chain issues, its not just the old stuff that is unobtanium! Which is, by the way a great word that I will have to remember!

[@mr-meek]

I'm taking Paul Carlson's advice on this one; paper and wax caps are not to be trusted even if they pass a leakage test at voltage. If you care about the device replace them! It's only a matter time

[@ElectromagneticVideos]

@@mr-meek Yes - one certainly can learn a lot about the long term reliability of components from the experiences of people like him with old equipment. I try and avoid most types of caps except ceramic for new designs - not always possible of course particularity when one needs large values = electrolytics (ugh!)

[@thecyborg6718]

Its unbelievable how much we advanced in just last 70 years, can't imagine how advanced aliens must be with millions of years before us.

[@JimTheZombieHunter]

I still use this technique .. not just for primary power, but (for example) to protect FETs in untested power circuits with various flavours of incandescents from flashlight to automotive turn signal bulbs depending on what's on the bench. One notable distinction you missed is with "better" though .. Series current limiting resistance (in this case a filament) and a fuse do two very different things. The ultimate purpose of a fuse is ONLY to protect the surrounding environment and upstream utility - not the actual equipment itself. In the silicon age, the kit may well be fried before a fuse gives up the ghost. Tube kit was more forgiving. On the other hand .. with that bulb, you have a 200W pass with a bit of Ohm's law fudge on a radio which requires maybe thirty .. Sure - if you know how to glean, a bulb suddenly or at full brightness is (very) bad, flip the off switch - but it's not inherently a protection device that will automatically save your input trafo if (say) the filter cap is short. In fact, it'll just prevent the tripping of the mains breaker. I don't want to be a troll or pick hairs, because as the world gets dumber there are less of us out there every day that still actually fix things .. and I enjoyed this video. but just calling apples and oranges.

[@ElectromagneticVideos]

Very good points - I guess I was trying to say a bulb is better than a fuse in certain circumstances. Very good point about tubes being more forgiving - more than once I have seen the plate of tube glow red hot and shut off the power and the tube survived once the cause was found. Not so with transistors.

[@insantiago798]

Is this considered a tube amp ?

[@ElectromagneticVideos]

If you referring to the old radio I do the demo with - well sort of! Its certainly includes a tube amp, but today when most people say tube amp the mean a tube amplifier that is only the amp - no radio or anything else. That radio does have the "warm" tube sound the people like about tube amps and its always nice seeing the glowing tubes - much more interesting to look at than transistors!

[@billbrown6526]

I've enjoyed a few of your videos, what is your background? You know more than you let on.

[@ElectromagneticVideos]

Glad you enjoyed them! Your right - and you made me realize I should fill out the YourTube about section! I'm a high-tech engineer - electrical and computer engineering in undergrad, and grad studies in optics and image processing. What makes me unusual is I love both the theory and practical side of things. It was a complete surprise to me that the "lets burn up a 14/3 wire" video on my obscure little channel go so popular. I guess now everyone things I'm the crazy guy who burns up things with a welder!

[@jonc4271]

WoW, I have the SAME radio at home in England 🏴󠁧󠁢󠁥󠁮󠁧󠁿🇬🇧 It is in FACT my friends. But he got his information a bit WRONG, as he told me that it was a WW2 radio, but I do NOT remember if it was on the inside or outside, it had an ink pad stile stamp on it with the year of 1960 or 61 ??? As I am NOT that sure when FM broadcasts first started, but I do “and did “ not think that it was in WW2 ????????? Wish I was able to send you a photo. But the BEST thing about this radio, is it’s sound and tone.

[@ElectromagneticVideos]

That neat! It is definitely post war and the 1960/61 stamp sounds right for the for the tubes (valve to you!) in it. FM broadcasting began in the late 30s but it only became common in the 40s after WW2. It had a tragic start (look up Edwin Armstrong) and that included a frequency shift to the current band in the 1940s. Your right the sound is so good! I want to do a video sometime on why tubes sound different from transistors - way more factors hat simply the tube characteristics - but a significant part of that radios sound I'm sure is the large speakers and being housed in a big cabinet. The cheap "All American Five" radios so common on this side of the Atlantic do not sound anywhere near as good. And the radio - and most German ones - were generally built simply with a much better quality mindset (and higher price). Put up a video - it would be great to see!

[@gavinminion8515]

I use light bulbs as DC electric fuses for battery boxes I build to power electric fences (for keeping animals in). a 12V 21W bulb will easily pass the 150mA needed to power the fence energiser, and if the output is short circuited or reverse connected, the bulb lights whilst the current is limited.

[@ElectromagneticVideos]

So for cow fences or do you do ones for bigger animals? I have seen them made for bears and wondered if they are setup to deliver a significantly bigger jolt. (From first hand experience I know the cow zapper jolt is - well - very attention getting).

[@gavinminion8515]

@@ElectromagneticVideos It's for horses, the energisers take about 150mA at 12V and produce a 7kV pulse with an energy of between 0.8 and 1.6 Joules every couple of seconds. There are other sizes (Down to about 0.1 Joule and up to 2.6 I have seen) but most are in the 1 Joule range. Interestingly, it's less about the size of the animal and more about their coat. Sheep need a much higher voltage (and energy) because they have thick wool. Horses need a medium power because they sometimes wear rainproof coats (here in the UK Western isles) which provide insulation. Pigs only need a low power fence as they are most sensitive. (That's the three animals I have fenced in/out!). The great thing about horses is they are quite clever, we don't want to Zap them, but they learn quickly to respect the fence and graze the marked area - you can often get away without turning the power on at all for a few days. If the horses really need to escape, they will either jump or barge the wire and break it (which happens too!) so we prefer it to barbed wire (which can be very nasty). We had problems with fences not working because the fuse had blown - nobody bothers to check if the energiser is working so the horses eventually figure it out and escape. So I replaced the fuses with light bulbs and the problem is now gone. And yes, we have all had a zap or two ourselves - unpleasant, but harmless.

[@ElectromagneticVideos]

@@gavinminion8515 How interesting! I never thought about how the coat being a factor but that makes sense. I can sure see the pigs with there almost hairless body like our being the most sensitive. Also interesting how smarter animals figure out things - they are often way smarter than we give them credit for. Also didn't know you could set the energy so precisely but with modern electronics not a hard thing to do. Somewhere in a shed I have an almost antique mechanical cow fence zapper. I'll have to find it and measure its output if it still works and see how it compares with your numbers.

[@gavinminion8515]

@@ElectromagneticVideos I perhaps gave the wrong imperession about the power output, whilst I'm sure there are types you can configure the output on, normally you buy the type best suited to your requirement. I also should have added that higher output is better for longer fences - we use 0.8 Joules for field separators (to control grazing) and 1.6 joules on the common (open ground) where the fence goes a longer distance. Thanks.

[@ElectromagneticVideos]

@@gavinminion8515 Oh - ok - no worries! Even at that, I'll bet in the old days it was much cruder in terms of estimating energy delivered per pulse if they even knew it at all. I can see the higher output for longer fences - more loading and leakage along the long wire I'm sure.

[@the_bigT]

I made something similar to test suspect or faulty electrical goods.

[@ElectromagneticVideos]

A few people have mentioned similar things!

[@dustinmiller7278]

Incandescents have been common up until about maybe 10 years ago

[@ElectromagneticVideos]

If your lucky, sometimes the dollar stores still have them.

[@Dazdigo]

There are fuses that use bulb sockets to connect to the fuse box.

[@ElectromagneticVideos]

Your absolutely right! There are some interesting comments below where people have described putting a light bulb in one of those sockets to help trace a fault.

[@zoppp621]

Doesnt this also result in a lot of wasted energy too?

[@ElectromagneticVideos]

You only use for a short time while testing - minutes to a few hours. It can save components from being fried by a short or other defective components. So a couple of cents of electricity is well worth it.

[@neail5466]

A shame that modern equipments are intentionally made to last only a couple of years, the olds really were gold. For the load tester one must have a assortment of incandescent bulbs 😁, I got a box of them.

[@ElectromagneticVideos]

Your not the only one hoarding old bulbs :)

[@alexoja2918]

Ah, I've been looking for high power resistors. Didn't think of bulbs.

[@ElectromagneticVideos]

The great thing about bulbs is how the resistance increases with temperature (~current) so you get a current limiting effect. Of course if thats not what you want for your application a bulb may not be for you unless your current draw remains roughly constant.

[@alexoja2918]

@@ElectromagneticVideos Oh, right! I wonder what the current-resistance curve looks like... probably not as ideal as a PTC thermistor

[@ElectromagneticVideos]

@@alexoja2918 I just googled i! Look here elektron.pol.lublin.pl/elekp/instrukcje_LV/Tungsten_resistance.pdf It looks pretty linear. I think the main difference is often resistors are bulkier and slower to heat up and cool down. If you can still find bulbs you sure cant beat them in terms of price for a power resistor. Someone commented about using a halogen bulbs for higher powers - I have never tried them - but another possibility.

[@alexoja2918]

@@ElectromagneticVideos Wow that's interesting. I thought it would be more of a curve as past a certain point the bulb starts to hit an exceptional temperature. I'm going to have to get a few incandescents and build a cable now.

[@ElectromagneticVideos]

@@alexoja2918 I was surprised how linear it was too! If you do build a setup post a video and let me know so I can see it!

[@laserflexr6321]

A rubber fuse is a great diagnostic tool that everyone who repairs electronics should be aware of. I just had to comment on something in the vid that sets off one of my obsessive compulsions. How many Sharpies or Magic Markers go in the trash not because they ran out of dye, nor that the tip is abraded that it makes too wide or an intermittent mark due to abrasion wear of the fibers, but because somebody left the cap off? Put the cap back on the Sharpie dangit! You are unnecessarily evaporating all the solvent.

[@thadrepairsitall1278]

As a mechanic I use this trick on cars to find shorts.

[@spqr528]

Yeah, a basic current limiter. I used cars turn signal bulb, zinc AA battery plate and piece of cloth soaked in hydrochloric acid for rust removal and electrolysis treat for the same said car chasis. Just hook it up on a cars battery, turn on the ignition and apply salvaged battery plate to corroded metal of the chassis. When the protective layer is deposited enough on the surface, bulb turns dim - indicating a successful application and thus limiting the current

[@ElectromagneticVideos]

Thats really interesting - never heard of that - but maybe old news for car restorers! So do you have grind or sandblast the rust away first or does it take care of the rust simply by electrolysis? And is the cloth placed between the corrosion and zinc plate or is is jut used to wet the area? I will have to try that sometime!

[@spqr528]

@@ElectromagneticVideos yes, wet cloth is there for transfering zinc salts onto steel metal. And yes, also theres prep work involved too, such as sanding and degreasing. I will try to find and provide yt link about the topic

[@spqr528]

@@ElectromagneticVideos its not a restoration by any means, but makeshift temporary solution to cover local area covered in rust

[@spqr528]

@@ElectromagneticVideos kzbin.info/www/bejne/rH_LnX55mNOXj5o

[@ElectromagneticVideos]

@@spqr528 I have to do some googling! That sort of thing would be of use up here with all the salt on the roads in the winter.