When a Light Bulb is better than a Fuse 

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.

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

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

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?

@@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.

@@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

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

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

@@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.

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

@@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.

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

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!

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!

@@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)

@@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.

@@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.

@@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!

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.

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.

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!

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

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

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!

@@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.

@@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.

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!

@@ElectromagneticVideos they're halogen now

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.

​@@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.

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

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?

@@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.

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

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 ...

@@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.

@@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.

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

@@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

@@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.

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.

@@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!

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!

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

Please explain more!

@@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.

@@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.

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...

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.

Even back then! Yes, great for reforming!

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

@@ElectromagneticVideos yeah lol. Here is Joshua's video on it! ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-I5a0TAmEwLE.html

@@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!

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!

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.

@@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 😲

@@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?

@@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,

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

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

@@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.

Yes - so simple yet so effective!

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?

@@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.

@@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!

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!

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

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?

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

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 ....

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!

Thanks! I'm glad it was understandable!

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.

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

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

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 :)

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

@@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 :)

@@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.

@@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.

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.

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

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.

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.

@@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.

@@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.

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!

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.

@@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.

@@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.

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

@@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!

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!

@@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.

@@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.

@@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.

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

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.

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

ru-vid.comS8ye7U8-78E cooler irl

The low voltage equivalent! What a great use - you made me think that I should setup something with a bulb like yours with some banana plugs to go between a power supply and experimental circuits.

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

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!)

An antique!

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

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.

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

@@ElectromagneticVideos 230v in South Africa

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.

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.

@@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...

@@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.

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

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$$$

@@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.

@@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 ;)

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

It is amazing how versatile the old incandescent bulb is!

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

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.

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 .....

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.

Thank you so much - I really appreciate it!

Your not the only one hoarding old bulbs :)

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" ...

@@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).

@@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.

@@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?)

@@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?

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).

@@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.

@@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.

@@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.

@@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.

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.

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?

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!

@@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!

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.

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

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!

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!

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

@@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!)

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!

Neat - the vintage German Radio are so nice!

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!

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!📻

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

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

@@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.

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

​@@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

There have been so many interesting applications posted here that I never would have guessed at and you just added one more - how interesting! Are they low impedance, or why the need for extra driver protection?

@@ElectromagneticVideos some speakers use fuses, this manufacturer used light bulbs.

@@kenschmidt6522 Interesting! I'm obviously not an audio guy!

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

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.

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

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

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?

@@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.

@@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.

Yes! Unfortunately many of those are relatively low wattage though ...

@@ElectromagneticVideos If you call 100W oven lights "low wattage," then maybe.

@@HylianOverlord Wow - I thought they were always 40W or so. I'm thrilled to hear there are 100W ones - than means 100W bulbs will be available for a reasonable time in the future!

I always thought that was so cool. Its neat to imagine someone in Europe in the 1950s moving the dial and selecting the city they wanted to listen too - it must have seemed almost magical back then! Soviet radio - that interesting - does it use European tubes or did they have their own different "communist" tubes?

@@ElectromagneticVideos I don't know much about vintage electronics it's just great grandfather relict but as a matter of fact they had to make their own because there was a trade ban on electronics in soviet block. I also know some frequencies were blocked (but it was perhaps in the later transistor era, dunno) to block western "propaganda"

@@give_me_my_nick_back Its so nice to have a a family memento like that! Trade ban - until the current trade ban the new Russians appear to have revived one or two tube factories and were doing a good business making new tubes for audiophiles and vintage equipment restorers. Jamming - I remember that - they did that lot on shortwave when I was kid!

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.

Well thank you!

Thanks! Glad you liked it!

That neat! Nice memory I presume.

A few people have mentioned similar things!

Thats really neat improvement! How do you sense the current? Low value resistor or current transformer? And to untrip it - just turn of power or is there an untrip/try again switch?

@@ElectromagneticVideos Sense with a current transformer, rectify that signal to DC then a comparator with the Threshold set. When it trips I have a MOSFET latch that holds down the "set" pin of the comparator and then a momentary "reset" push button. I also have a 10 LED meter ranging from green to yellow to red as the current gets closer to the threshold it will blink faster and faster till it trips then all of them are blinking, so it's a great visual cue. I've been thinking of selling it as a kit to amp tinkerers and the like

@@prattacaster Sounds like a well thought out and tested design. I think a kit would be fantastic! And even if not a complete kit, but a printed circuit board and a list of parts might be a great way to test the market. Hope you have a go at marketing it!

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

That would work nicely and also be really convenient for gradually upping the current if they were independently switched.