Why do incandescent light bulbs have a frequency rating?

[joseph nicholas]

I use a dim bulb circuit to power up test equipment in case of shorts.  It uses a 100 watt light bulb.  Printed on the bulb it says 60Hz.  Why?  I'm curious to why this needs to be there?  I know why it tells me the voltage and I know why it has a power rating, buy why frequency?  Very curious. 

[spec]

Hi joseph nicholas

I use a dim bulb circuit to power up test equipment in case of shorts.  It uses a 100 watt light bulb.  Printed on the bulb it says 60Hz.  Why?  I'm curious to why this needs to be there?  I know why it tells me the voltage and I know why it has a power rating, buy why frequency?  Very curious.

If the bulb is only a filament type, I would not read too much into the 60Hz label. Read it as, 'suitable for 60Hz'. In practice, the bulb would be suitable for a whole range of frequencies, but at the lower frequencies visible flicker may be apparent and at the higher frequencies losses due to parasitic inductance and capacitance would limit the performance. At a guess, I would say that the bulb would operate OK from 25Hz to 450Hz. The slow response time of the filament will eliminate flicker at 25Hz.

But there is another aspect. That bulb may only have been certified at 60Hz, so the manufacturers are legally obliged, to limit its use to 60Hz.

[NiHaoMike]

Ask the amateur radio operators and they'll show you an incandescent bulb running well into the MHz.

[james_s]

Are you sure it's actually incandescent? I don't recall ever seeing one with a frequency rating printed on it. I do have some LED bulbs that look exactly like incandescent from the outside though.

[spec]

Ask the amateur radio operators and they'll show you an incandescent bulb running well into the MHz.

Is that right. I learnt something today

[Ian.M]

Are you sure it's actually incandescent? I don't recall ever seeing one with a frequency rating printed on it. I do have some LED bulbs that look exactly like incandescent from the outside though.

Any sort of LED, CCFL or non-incandescent 'eco' bulb is *NOT* suitable for use in a dim bulb tester
.
If its a clear bulb the LED 'filament' fakes are pretty obvious.  The 'filament' is far thicker and doesn't have the characteristic grey metallic look of a double coiled Tungsten filament.  If its a frosted bulb, and there isn't enough unfrosted at the base to see the filament, its a bit harder.   Pop it on a variac and see if it gets redder and evenly dimmer as you reduce the voltage.  If it stays the same colour and possibly fickers, its LED!

[SeanB]

Generally the reason they rate incandescent lamps for AC is because of failure. When the lamp fails on AC there is a pop, a bright flash and the arc goes out at the next AC zero crossing. On DC the filament breaking forms an arc, and this will continue to melt the electrodes, till the glass seals are burnt away, and in cases they can continue down the glass as it is melting and thus conductive. Might not be enough current to blow the fuse, and fuses rated for high voltage DC ( anything over 50V) are both specialised and expensive. They do make high voltage DC lamps, but only for really specialist use, and there the construction is different, having both longer filaments, different supports and need fusing per lamp.

I have taken a blown linear halogen lamp and connected it across a neon transformer ( 14kV 30mA current limited output) and the arc energy was doing a good job melting the tungsten filament back and, when it reached the seal, the glass itself was arcing as it melted, till it finally broke apart from the thermal stress. Even then there was a short arc in air till I pulled the parts far enough away and turned off the power. AC yes but the arc is the important part, especially in a low pressure lamp environment.

[joseph nicholas]

Hi Spec, I think your right in saying not to read too much into it.

It definitely is an incandescent bulb.  You can still buy them here in Mexico and they are probably made in China and they are extremely cheap.  People sell them in the markets along with the CFL types.   

[MrAl]

Hi,

I happen to have a 25 watt incan sitting right here and i just looked at it and it says 25 watts 210 lumens but no frequency rating.
It also says "2.3 year life" with an asterisk after it (ha ha) and in fine print is says "based on 3 hours per day use".  So that's about 3.5 months running 24/7.

Some soldering irons however have the frequency rating because they work on AC only because they might use induction heating too.

[soldar]

The slow response time of the filament will eliminate flicker at 25Hz.

Years ago I designed a way to detect if a shaft had stopped rotating and it was a cross of Malta type thing rotating with the shaft and the blades interrupted the light from a tiny lightbulb to an LDR. The circuit detected the on/off light at the LDR and if it stopped it would activate a circuit. Except that it would just not work. After much investigation I found out the LDR response when receiving light from the light was not flat but was very visibly modulated at 100 Hz. The filament had low thermal inertia and light emitted varied over the cycle. Once I powered the light with DC the problem disappeared.

I also remember a circuit which would transmit voice over the light beam of a car's headlight. Obviously the light emitted by the filament was not modulated to 100% but there was enough modulation, maybe 5 or 10%, to transmit voice over the beam. I thought it was neat and always thought it would be a cool thing to build.

[james_s]

It takes a significant amount of time to vary the light of an incandescent lamp between zero and full output, but it can be modulated to a lesser degree at significant frequencies. This is particularly true of small filaments with relatively little thermal mass.

[soldar]

It definitely is an incandescent bulb.  You can still buy them here in Mexico and they are probably made in China and they are extremely cheap.  People sell them in the markets along with the CFL types.

I think you can still buy them in dollar store-type small shops here in Spain even though they are supposedly illegal. Maybe the importation is illegal but old stock can still be sold. And maybe old stock is mysteriously continuously appearing direct from China

I hate this type of regulation because if the alternatives are so much better then people will go to them on their own but sometimes people have their reasons for continuing to use the old thing.

For years I have used CFLs in some places but they have their drawbacks and I kept incandescents in some places. In the bathroom, with the steam of the shower, CFLs did not last long. Add the fact that CFLs take a while to reach full brightness and that the bathroom light is not on for too long and it just makes sense to keep incandescent.

Sometimes the new bulbs just do not fit in the old fixtures or lamps.

CFLs were sold with the promise that they would last forever but in fact mine did not last too long. Sometimes the tube and other times the electronics would fail.

I have a computer which has the strangest problem. Most computers have problems when they get too hot but I have a computer that hangs in cold winter weather. It took me a while to figure it out but now I just heat it and the easiest way is with a small incandescent light bulb. I place a 50W light bulb inside the case but run it through a triac power control and usually run it at about 20 or 25  watts.

Meet the heatball: https://en.wikipedia.org/wiki/Heatball

I have a good stock of incandescent light bulbs, enough to last me the rest of my life, but if I ever need more I will just bring them back from China when I go there.

[james_s]

I hate this type of regulation because if the alternatives are so much better then people will go to them on their own but sometimes people have their reasons for continuing to use the old thing.

Here in the US the ban covers conventional incandescent lamps, but there are exemptions for various types of decorative lamps, special purpose lamps like for ovens and rough service bulbs, and there are halogen bulbs that are marginally more efficient than conventional incandescent.

I don't like bans either, I would prefer to tax the less efficient lamps and use that to subsidize more efficient lamps. It's a nice idea that people given a choice would choose the better option but in practice people have demonstrated time after time that the average person is simply not informed or not intelligent enough to make an educated decision. Making up some numbers for the sake of example, if you offer a bulb that costs 10c, lasts 1,000 hours and consumes $10 worth of electricity, next to a bulb that costs $10, lasts 10,000 hours and also consumes $10 worth of electricity (because it's in service 10 times as long) it's quite obvious that the total cost of the $10 bulb is in fact much cheaper, but the average person will choose the 10c bulb almost every single time because they look at the price tag and see that it's cheaper.

I remember a friend trying to explain to a friend of his that a high efficiency air conditioning unit would save him money vs one that cost significantly less to install but the guy just couldn't seem to grasp it, even when offered a comparison like the miles per gallon of a car. For reasons I don't really understand, a lot of people don't seem to be able to make the connection between the energy consumption of a device and their monthly utility bill. Sure if you replace one incandescent light bulb with an LED bulb you probably won't notice a change in your utility bill, it's not visible through the noise. If you replace all of the frequently used bulbs all at once though the difference is substantial, especially when spread over several years.

I was an early adopter of LED bulbs, being an engineer I was able to see that even spending $40 each that they cost at the time was a good deal because the total cost over the life of the lamp was lower. It was readily apparent that most people lacked this sense though as sales didn't really take off until the mandates and subsidies got things rolling, overcoming the chicken & egg problem, production ramped up, costs rapidly dropped. That may well never have occurred if not for the regulations giving it a kick in the pants. People are notoriously short sighted, one need look no further than the average amount of credit card debt in the USA, which I suspect is not terribly unique to this country. A great many people base their financial decisions on what something will cost today or per month, completely ignoring the total cost in the long term. This is why you can even "rent to own" things like furniture and electronics, the final cost is far higher but $50 a month for 2 years looks a lot cheaper to people than $500 up front. Doesn't make sense to me, it's not rational, but it has been demonstrated over and over and over again.

[joseph nicholas]

Soldar, that is one very unsual computer you have there.  To get it where it makes you happy by sticking an incandescent lamp inside its case needs more investigation.

[spec]

At home we went from filament, to EL to LED.

The light from filament bulbs is natural and pleasant,  but they use so much power that the heat deteriorates many light sockets and the wires going into the sockets, not to mention the cost of the wasted electric power.

EL fixed the heat issue and the later EL bulbs had a more natural light output, and they turned on faster, but all of the types I tried were unreliable, and no where met their claimed life. Not only that, but the light output reduced with age.

We are now progressively changing over to LED, and what a difference. Instant turn on, high efficiency and, depending on what temperature you choose, and beam angle, a pleasant light. Only time will tell, but after a year, none have failed which bodes well for the reliability.

Another advantage with LED bulbs is that they seem to be a lot more robust, which is an important factor when you are using them in lead lamps. With filament bulbs, you had the heat issue, which could be a problem if you are crawling around under a car and the lead lamp is near to your face.  And if you dropped the lead lamp the bulb would blow. EL took care of the heat issue but they were even more fragile. But LEDs, so far anyway, don't seem to have this problem. I expect one day I will bite the bullet and change the lead lamps to battery-powerd LED versions.

[soldar]

It's a nice idea that people given a choice would choose the better option but in practice people have demonstrated time after time that the average person is simply not informed or not intelligent enough to make an educated decision.

Let's try to keep Brexit and the results of recent elections in other countries worldwide out of this

Democracy is a pathetic belief in the collective wisdom of individual ignorance.

Henry Louis Mencken (1880 – 1956)

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Making up some numbers for the sake of example, if you offer a bulb that costs 10c, lasts 1,000 hours and consumes $10 worth of electricity, next to a bulb that costs $10, lasts 10,000 hours and also consumes $10 worth of electricity (because it's in service 10 times as long) it's quite obvious that the total cost of the $10 bulb is in fact much cheaper, but the average person will choose the 10c bulb almost every single time because they look at the price tag and see that it's cheaper.

I remember a friend trying to explain to a friend of his that a high efficiency air conditioning unit would save him money vs one that cost significantly less to install but the guy just couldn't seem to grasp it, even when offered a comparison like the miles per gallon of a car. For reasons I don't really understand, a lot of people don't seem to be able to make the connection between the energy consumption of a device and their monthly utility bill. Sure if you replace one incandescent light bulb with an LED bulb you probably won't notice a change in your utility bill, it's not visible through the noise. If you replace all of the frequently used bulbs all at once though the difference is substantial, especially when spread over several years.

What is it to you? It is their money. It is not like you are paying for it. People spend their money in ways I would not. So what? Isn't that what freedom is about? Suppose I want to fill up my swimming pool with the most expensive French Champagne; most people would say it is a waste but the question is if I should have the freedom to use my money as I want and not as others want. I paid for the champagne and it is mine to do as I please with it.

Many years ago, when I was much younger, I had a girlfriend who would have on all the lights in her apartment all the time, even all night when she was sleeping, and I, being young and foolish, would argue with her about the need to save the planet and all that. Of course, it didn't do me any good. In her apartment she could do whatever she wanted. She told me it made her feel safer. I thought it was silly but it was not my choice to make. If paying for that electricity made her feel better it was a very rational thing to do even if it seemed foolish to outsiders.

 Most people who have SUV's do not "need" and SUV and yet we give them the freedom to own one. Who knows what goes through their head. They do not need an SUV from a practical standpoint but the obviously have their reasons like they feel richer in front of the neighbors, or more attractive, or safer, or who knows. We do not need to understand their reasons. That is what freedom means.

We were told CFL's would last much longer than incandescents and that turned out to not be true. So we were lied to and we paid for the lie.  If I have my reasons to prefer an incandescent light I should not be prohibited from using one or forced to explain my reasons. And if others believe my choice is foolish I should still have the freedom to do it. That is what freedom means.

If I am in a house renting for a year I might decide it is not worth an investment that takes many years to pay back for itself. Maybe I get an appliance that is less efficient but much cheaper. I should have the freedom to do that and not have my freedom limited by bureaucrats who know nothing about my particular circumstances and preferences.

Maybe I have a gas guzzler and could save in the long run by buying a more efficient car but I should not be forced to do so. Maybe I do not drive enough miles to make it worthwhile. (BTW, yesterday I saw a 1978 Bentley and got talking with the driver and he told me it only had about 25000 miles on it.) Maybe I am just in love with my old car and I am willing to pay the premium. As long as I am the one paying for the fuel and maintenance why would anyone care what I do with my money?

Periodically there is rumbling about golf courses using "too much" water and prohibiting them from doing so. My view is that if they are paying for the water at whatever everybody else is paying for the water then they should be free to use the water for whatever they want. They say we should take showers and not baths because that saves water. And we should not water the yard in times of drought, etc. As a suggestion that is fine but I have a problem when those things are enforced by regulations. What if I prefer to take one bath a week rather than seven showers? Are we going to control what people do to the point of checking that they close the water faucet while they brush their teeth?

I want the freedom to use incandescent light bulbs and I have my reasons even though others may not share them.  I have an incandescent light bulb in the well that houses the pool filtering system because I leave it turned on when there is danger of freezing. Why should I be forced to fit a low energy light and then separately a heating system?  I have an incandescent light in the bathroom because it is the only type that has proven immune to the steam from the shower. Anything with electronics has a short life.

So that is how I became an outlaw. Then I went on to remove labels from mattresses and a long list of other nefarious acts.

[spec]

Soldar, that is one very unsual computer you have there.  To get it where it makes you happy by sticking an incandescent lamp inside its case needs more investigation.

Quite often that sort of symptom is caused by poor connections. It may be on a connector or on a PCB. Often a general clean and check of all the connectors will do the trick. And just plugging and unplugging connects can clean the contacts to a degree.

Another source of problems is that connectors may not be fully home. I had this with a laptop which had a second HDD in a bay. Every so often the HDD would not show. The problem was that there was enough space in the bay for the HDD to become slightly away from its mating connector. A rubber pad took out the slack and since then the HDD has worked fine.

[spec]

This thread is turning into a general chat about life, the universe, and everything. But I suppose that is OK because, hopefully, the OP's question has been fully answered.

So, I would like to ask if anyone can remember the circuits that used filament bulbs as a PTC elements (10:1 increase in temperature from cold to hot). For example, I think small bulbs were used (in place of an R53? thermistor) in some phase shift oscillators to control the loop gain. And there was a little booklet of bulb circuits available at one time.

[soldar]

Soldar, that is one very unsual computer you have there.  To get it where it makes you happy by sticking an incandescent lamp inside its case needs more investigation.

It is a Mini ITX VIA EPIA ME6000G running Win XP SP3 and which I use solely as a router in my second home which is not heated when I am not there.

Some years ago it started failing and I spend many hours troubleshooting it but I could never really determine the cause of the problem until I realized it happened every year as the cold weather arrived.  I changed PSU, hard disk, etc. but nothing fixed it. I seem to remember memtest would give errors. It is definitely a mobo issue. Maybe a bad solder joint, electrolytic cap or... who knows.

At first I just put a space heater at some distance and when I saw that fixed the problem I realized I did not need to have a 600W heater on all the time but a 20W bulb inside the case would do. In fact I have a digital thermometer that shows the temperature and I try to keep it around 25ºC. Oh, of course, I disconnected the case fan.

That router allows me access to my security cameras from my main home.  Last week I could not access them and I was concerned there might be a power outage or something serious so I went with a friend to check and I found the light bulb had blown and was dead. I commented to my friend how utterly strange it is that a light bulb running at low power with a dimmer would blow. He insisted the power level at which the light is run has nothing to do with it and I didn't want to argue so I left it at that. To me it is obvious that running an incandescent light at less than full power will make it last longer.

Anyway, as I say, that computer is in my other home so I cannot post a photo now but if I remember I'll do it when I go there.

[GreyWoolfe]

I have an incandescent light in the bathroom because it is the only type that has proven immune to the steam from the shower. Anything with electronics has a short life.

Interesting that you say that.  We have 2 LED bulbs in the fixtures on each side of the master bath mirror for about a year without an issue.  When the CFL bulb in the exhaust fan burns out, that will also be replaced with an LED.

[soldar]

Yes, I have been replacing lights with LED fixtures and I am extremely happy with them but CFL's left a lot to be desired and I believe their life and performance were much exaggerated.

I suppose an LED replacement bulb which is totally sealed and tight should not have problems with condensation. The problem with CFL's is the have openings for ventilation and cooling and water condensation in there means short life.

Another place where I cannot replace an incandescent is in my test rig where I use an incandescent light bulb to limit current into devices I am testing. An incandescent light bulb is just ideal for this.

[MrAl]

The slow response time of the filament will eliminate flicker at 25Hz.

Years ago I designed a way to detect if a shaft had stopped rotating and it was a cross of Malta type thing rotating with the shaft and the blades interrupted the light from a tiny lightbulb to an LDR. The circuit detected the on/off light at the LDR and if it stopped it would activate a circuit. Except that it would just not work. After much investigation I found out the LDR response when receiving light from the light was not flat but was very visibly modulated at 100 Hz. The filament had low thermal inertia and light emitted varied over the cycle. Once I powered the light with DC the problem disappeared.

I also remember a circuit which would transmit voice over the light beam of a car's headlight. Obviously the light emitted by the filament was not modulated to 100% but there was enough modulation, maybe 5 or 10%, to transmit voice over the beam. I thought it was neat and always thought it would be a cool thing to build.

Hi,

There is a model on the web somewhere i remember downloading years ago.  It includes thermal properties like time constant.
You'd have to find it i guess with a search.  You can then use it in a simulator to simulate a light bulb.

[soldar]

Here's one From Elektor 1979.

[james_s]

I have had LED bulbs in my bathrooms since 2011, the same Philips bulbs, they have never failed. I have not used a standard incandescent bulb for general illumination in 20 years, so frankly it always surprises me when someone is moaning about them being phased out. Especially when you can still get them for special applications. Standard "type A" or GLS style bulbs with halogen capsules in them are readily available and behave exactly like a traditional bulb with slightly higher efficiency. There are zero applications that require incandescent bulbs for which you cannot still get them, although you may have to look just a little bit harder they are available.

Yes it's their money but you are not seeing the bigger picture. If we did not nudge people into switching, LED bulbs would not have come down in price for everyone else, the technology may have failed entirely due to high initial costs, we would still all be stuck with incandescent bulbs or inferior CFLs for years, possibly decades. There are collective costs to us all in the form of higher energy consumption resulting in environmental pollution, increased infrastructure required, increased energy costs and other factors. You do not live on your own little isolated planet where you can be as wasteful and polluting as you want without impacting anyone but yourself, some things that you do affect all of us and this is why it's necessary to make choices for people sometimes, because they have demonstrated that they are unable or unwilling to choose sensibly for themselves having been given that chance. I was never impacted by the incandescent bulb ban. Why? Because I made a sensible choice and phased them out myself a decade before the ban even happened. It was literally a complete non-issue, I was shocked to hear that so many people were still using old fashioned bulbs to light their houses. I mean I had a rotary dial telephone plugged into a real landline more recently than I had an incandescent bulb in a table lamp.

Without regulations we'd still be driving around in carbureted cars getting 12 mpg with no catalytic converters because hey it's our money and we can do what we want with it, these cars are cheap, great, but we'd all be choking on smog and there would be some serious pain when the fuel shortage does eventually drive innovation to improve fuel economy. It was better that these improvements were mandated *before* we had a catastrophe on our hands. People in general are far too self centered and look only at the short term, so sometimes it is necessary to nudge everyone forward so we don't all get held back by their stubborn refusal to move forward.

[soldar]

... you may have to look just a little bit harder they are available.

I don't have to look hard at all as I have a stock to last me the rest of my life and I travel to China regularly so I could always get some more there.

of course I expect the tree-hugging SJW to condemn my lack of solidarity.  The same ones who drive huge SUVs and use ten times more energy than I do. You can't win for losing.