LED will not dim properly without one incandescent bulb in circuit

In my experience, the new twisty bulbs don't dim very well. I have a fixture over my kitchen table with 5 sockets, on a dimmer. I replaced the incandescent bulbs with these . They didn't dim very well at all, although somewhat, but to my surprise burnt out in a matter of days! The twisty bulbs are not LED's, but some sort of florescent I figure. I've put a bunch of these in other places, ( non dimmed ), and they seem to work OK, except my reading light, not enough power for these old eyes, and they seem to flicker or something, I'm not sure, but it gets unpleasant after a while. Anyway, the jury is still out, will the much greater upfront cost really show a drop in my electric bill over time? I mean so much so that I actually see it?

Bricktop I've always been told that you should not use a dimmer switch with any fluorescent lights including CFLs. I didn't even know they made F Lights that could be used with a dimmer switch.

Guest: You mentioned that some of the LED lights dimmed while others did not. But you also said you where trying different types to see what worked best for your situation. Where you using all the same lights at one time or did you have more than one type in use?

I'm looking into replacing my lights with LEDs as they burn out and the more info I have before then the better. Did you buy them off the net or locally? No one in my local area sells them yet.

scotchdrnkr; it's not the lamp, it's the special manufacturer ballast & dimmer that lower the light output. perry

You probably don't have enough of a load to draw down the circuit. Try placing a large resistor in parallel with your lighting circuit.

shawn v elect

Exactly what size resistor should I use?

?Do resistor's come in 120 volt style?

Thank You

George

If the original poster did that, then there wouldn't be any power-saving advantage in comparison with using incandescent lamps.

One of the options available to the original poster is to bank the new lamps into several switched circuits and operate less than all of them at any time.

I have tried the twisty CFL that use 15 watts. If you want to use a dimmer switch you have to buy the dimmable cfl's which are available but cost about twice the price ($18.00). I have several of them and have been working for about 6 months and only one has burned out. They dim in jumps and do not dim very very low. The LED that I have tried dim very similary to incandescent bulbs and are only 4 watts (= approx. 50 watt incandescent).

This is a very good answer. Actually, the only good answer for the above enunciament of the problem. So why I DO NOT give you a GA point? Because I wanted to give this answer, you bit me by a moustache

Does anyone know what type of dimmer or where can I get the proper dimmer?

Thank you

George

I can only guess. Those dimmers use a triac as a variable "on" time device. They (the triacs or SCRs) have a so called holding current. It is possible that your LED are on a serial string so the current through them is some 20 mA. If this is the case, you need a small triac (in a TO92 casing) that has, for sure a holding current less than the 20 mA, say some 2-3mA so, when you dim the light (the current through the LEDs drops), your triac is still open for the set duration.

If you have a bit of application as a bricoleur, you can do yourself.

I have no idea where to buy but the word would be: very low power!

Indel is absolutely correct, the LED bulbs alone do not provide enough current. It may be the holding current is too low or the latching current is too low so the triac does not stay "on" or latched. A small incandescent bulb ups the current enough to allow it to work. It probably only needs to be a relatively small incandescent bulb, as little as 15W may do it. A more elegant solution would be to try a dimmer for MLV (magnetic low-voltage). These dimmers typically have a neutral wire and a constant gate signal so would not have the latching issues as they are designed to work with magnetic transformers. An ELV (electronic low voltage) dimmer would work also as it is a FET based design and does not require a minimum current draw.

Shawn

Yes. Have a discussion with the local friendly lighting equipment supplier. They provide brilliant answers to these questions.

Excellent, Upped you one. Best/easiest way of doing it.

This is almost off topic, but I think I'll call it on topic.

I've noticed that LED taillights on certain cars (but not all those with LED lights) are pulsed at about 60 Hz when in the taillight mode (as opposed to the brighter brake light mode. The reason I know they are pulsed is that when my eyes scan around the road, fairly rapidly moving from side to side, I see multiple images of these lights. I think I don't see these multiple images when the bulbs are in the bright mode (although maybe I don't want to see them, because it would not support my theory). So my theory is that in the taillight mode the duty cycle is something like 50%, and in brake light it is 100%.

I haven't looked closely at led lights for home use, but assume they have a screw in base with the electronics to provide fairly smooth dc -- otherwise the flicker would be annoying, I'd think. So using a dimmer on the input would seem to be subject to plenty of problems: you can imagine circuits in which dimming the source by thyristor would have no affect at all on the light brightness.

It would be interesting to make a system in which the dimmer circuitry is built into the base of the bulb, and that circuitry would be commanded to adjust by a frequency generated by the "dimmer control switch". The bulb base receives a particular superimposed frequency, and adjusts brightness accordingly.

Alternatively, I suppose the control function could be Bluetooth. The dimmer circuitry would still be in the bulb base which would also contain a Bluetooth receiver. Each person in the household would be equipped with Bluetooth commanders (wrist watch, ear rings?) which would default to automatic mode, in which the lights come on as you enter a room, and turn off when you leave. But turning a knob on your commander would dim the lights. The commander could be installed under your skin and voice controlled.

Clearly, it is too late here, and I'm starting to go off the deep end.

A little off the subject; BUT...

Try X10.com

They already have what your are talking about. It's not blue tooth, but all you have to do is screw a X10 adaptor onto the bulb, then screw the bulb into the socket. Plug a X10 reciever into an outlet. You can control the light with various devices; push button wall fixture, hand held "remote control" type switch or a key chain push putton controller. You can even connect a wireless motion sensor to make the light come on. My old house was all X10, I could even control the light using the computer or over the internet, even had various camera's for security.

Good point. In fact, I though of X10 as I was writing the post. I haven't looked into X10 stuff in ages -- and have never felt compelled to get a system set up. Not that I don't think it would be fun... just haven't had the time. In addition to being fun, it seems there are all sorts of useful stuff it can do.

oh x10, where theres always a deal ending in less than 10 hrs...

WWW.ledtronics.com Has a large selection of replacement LEDs. There are also LEDs designed to replace the bulbs in "exit" signs that are easier to find. Keep us posted. One of our radio techs has been installing LEDs throughout his house, but he has been wiring his house for low voltage.

Guys,

LED lamps are very different from CFL lamps which are mini flourescents.

Most current CFLs are not capable of being dimmed; some of the newer ones may be.

A special dimmer is likely to be required for this application.

The suggestion that one incandescent lamp in the circuit "enables" the group of lamps to be dimmed is probably down to the incandescent helping the dimmer to stabilise the voltage applied to the group by providing a more stable load. But it will not help CFLs to have a wide range of luminance as they will cut off at low voltage and luminance levels.

For LEDs one really needs a driver circuit for each lamp , or group of lamps. Dimming of these ought to be possible; but I do not know of a dimmer system yet available - I would really like to be advised if someone has some up to date information on this point.

The circuit drivers are required as LEDs require accurate current (think diode which is what LEDs are) rather than the voltage that is available and applied to all other lamps.

We should keep each other informed as to Technical progress on these point.

Sleepy

Gentlemen,

both LEDs and CFLs are NOT dimmable unless it says so on the packet. Dimming the wrong way will only drastically shorten their lives.....

Either buy the ones marked as dimmable (making sure that the dimmer you are using is of the correct type) or just leave well alone.

Megaman have a new range of CFLs that are dimmable, I have never had one of their CFLs go defective on me in the last couple of years.....though I have yet to try the dimmable ones.....

Although you addressed your post to "Gentlemen" I will answer by contradicting half of your affirmation. As long as, by any means, you can control the current through LED's, your lamp is dimmable. A current generator voltage controlled, or even a resistor can control the current (therefore the light intensity). This is why, replacing the power triac, in the problem shown by Guest (by the way, this Guest guy has a very inquisitive mind, he posses the most questions on this forum!), so replacing it with a low power one, one can dim the LED lamp IF a limiting resistor is added in series with the led string.

I suspect that you have not looked inside a mains LED or CFL and seen the electronics inside......

It is this electronics that reacts quite badly to dimmers being used, when the electronics was NOT designed to be dimmed in the first place.....even when the LED lamp does not work anymore due to damage, it is usually not the LEDs themselves that are broken, it is this electronic module. Some dimmers give out an AC form that has little to do with a Sine wave, it is this non Sine wave that causes the damage. Click on this link and read down and you will find an explanation for this damage!!

Look under the heading:-

Lighting LEDs on mains

Mains LED lamps

The same goes even more strongly for CFLs....

Your comments show that you only understand LEDs when playing with a battery and a few resistors! Very, very basic.....The electronics I am talking about are several powers of complexity and miniaturization higher than that!!!

As a start, why not just read the instructions supplied with such modern low power lighting if you do care to believe me.....? I have thrown away the packaging information that came with my last batch, otherwise I would have copied it and placed it here for you to read and inwardly digest!!!

Try looking at this page, maybe you will improve your "expert" knowledge a little more with regard to CFLs as well....!!

megaman

Here is a short excerpt from the web page in question!!

Smooth Linear Dimming with Tremendous Energy Savings

MEGAMAN^® has invented the world's first linear dimming CFL that is operable on conventional dimmer switches, and allows you to choose between full output or atmospheric lighting. The DIMMERABLE lamps work perfectly on any incandescent dimmer or electronic scene setter with absolutely no additional control wiring and transformers needed.

Basically said, your earlier comments were 100% false and inaccurate!!!

I suspect that you have not looked inside a mains LED or CFL and seen the electronics inside......

It is this electronics that reacts quite badly to dimmers being used, when the electronics was NOT designed to be dimmed in the first place.....even when the LED lamp does not work anymore due to damage, it is usually not the LEDs themselves that are broken, it is this electronic module. Some dimmers give out an AC form that has little to do with a Sine wave, it is this non Sine wave that causes the damage. Click on this link and read down and you will find an explanation for this damage!!

Look under the heading:-

Lighting LEDs on mains

Mains LED lamps

Your comments show that you only understand LEDs when playing with a battery and a few resistors! Very, very basic.....The electronics I am talking about are several powers of complexity and miniaturization higher than that!!!

Dear Andy,

Something I said must have irritated you, so I try to say it again, with explanations:

-Gentlemen and engineers – an usual greeting of one professor that I liked. That implied that engineers are not gentlemen, and this was my auto-irony try.

-I was talking about LEDs and the possibility of dimming a string of LEDs. It is a basic operation, when you have the voltage available. As you said, a battery and a resistor would enough. Higher the voltage, more LEDs you can add in the string.

-Our friend Guest has a dimmer, which, basically, is a triac with the phase control. On a resistive load like a incandescent lamp, the dimmer was working. He replaced the incandescent with LED lamps and the dimmer wasn't working unless he loaded with one incandescent. This is, obviously, a problem of triac, that can be solved by replacing with the appropriate one.

-I haven't looked inside a mains LED lamp, indeed, but I have designed and built for lower voltage (48Vdc). All boost drivers for LEDs are rather complicated designs but all have something in common: they just rise the dc voltage to a higher value (so more LEDs can be set in the string) and they provide current control. It is what I have said.

-Because you have mentioned, please detail what complicated circuits are in a mains LED lamp, with a different function from rectifying and limiting current. We are not talking about CFL. Now, here is what I said and what Wikipedia (your link) says, too:

Indel:

As long as, by any means, you can control the current through LED's, your lamp is dimmable. A current generator voltage controlled, or even a resistor can control the current (therefore the light intensity).

Wiki:

Lighting LEDs on mains

A CR dropper (capacitor & resistor) followed by full wave rectification is the usual ballast with mains driven series-parallel LED clusters.

I feel that you have no further interest in learning something useful going by your latest post because in my last post, I gave you a link to look at and also where to look under that link to find out why it is not a good idea to try and dim MAINS LEDs as a general rule with ordinary dimmers. Mainly this is due to the waveforms produced by the Triacs when switched in causing heavy currents to flow at lower voltages. Please look at that link and maybe you might learn something.....

For your education, certain dimmer circuits, using Triacs, actually "cut up" the mains, producing square waves and resultant harmonics. It is these harmonics that cause the problems I was talking about........

Look at this link for example, which talks about Triacs and their problems in this area:-

Triacs

Checkout the whole paragraph on that link that starts:-

TRIACs are notorious for not firing symmetrically.

Show me this time that you have taken the trouble to actually look at what I am posting FOR YOU PERSONALLY, so that I have no need of the following saying/proverb....

An old proverb, it says "You can lead a horse to water, but he must drink all by himself!"

I feel that you have no further interest in learning something useful .... Please look at that link and maybe you might learn something.....

For your education........

Show me this time that you have taken the trouble to actually look at what I am posting FOR YOU PERSONALLY, so that I have no need of the following saying/proverb....

An old proverb, it says "You can lead a horse to water, but he must drink all by himself!"

Dear Andy,

Facts:

-There are LED lamps, to work on a 120Vac line

-There are dimmers, using triacs, for RESISTIVE loads, as an incandescent light bulb (ILB)

You try to stress on the fact of asymmetrical firing in a triac, and therefore, on the creation of harmonics. It is strange the way you imagine those harmonics, but if you get a scope, you will see that, actually, those harmonics from first=fundamental to the last significative one - odd or even, those harmonics I said, will combine and the Fourier series that is in your mind, is actually a wave, quasy sinusoidal (due to harmonics), but an alternative voltage, going from about -167 to +167V, within 8.33msecond. This will not affect AT ALL the functioning of the LEDs, which are set to work – one string at a time – on the resulting pulsed or filtered positive voltage for any and each of the alternances of your dirty ac line. LED is a RESISTIVE load, the circuitry in the LED lamp take care of any over voltages (from where? There are not inductive loads around).

Please explain: Triacs when switched in causing heavy currents to flow at lower voltages.

Where are those heavy currents coming from. Between the power source (the 120Vac outlet) and the RESISTIVE load that is the LED lamp there is the triac. Even if your triac is a crazy one and behaves as a zero ohm devices or even a negative resistance, the voltage on the RESISTIVE load LED cannot create a current more that what the designer wanted (and actually, the voltage has to reach a certain voltage for the LEDs to "fire" = light).

One more time (and the last one) a LED lamp (replacement of an 120Vac incandescent lamp) CAN work on a triac driven dimmer (if the latch current is small enough – as we discussed previously).

Dear Andy, your postings are aggressive, and arrogant to my assertions which I don't think that are fitted for a technical discution.

At this moment I stop answering your interpellations and I ask our colleagues to arbitrate this discution.

PEOPLE, PEOPLE, PEOPLE

I don't want to start a fight, I was only trying to find out why (and a possible solution) as to why my lighting circuit works when I install one incandescent bulb; and why it does NOT work when only LED's are installed. As to LED lifespan I will cross that bridge when I get their. Right now the LED's (? non-dimable as per the package) dim quite nicely. And if all else fails I will replace the dimmer switch to a standard on/ off switch.

I want to thank everyone for their input. I have learned alot from this thread as well as from this Forum (CR4). I have several ideas that I will have to check out. When I find the best solution I will let everyone Know.

Thank You

George

Read the proverb from my last post, it fits the situation perfectly!!!

You still have not taken the time to bother to learn something fully and correctly in spite of having the links presented to you on a plate. End of story is that you understand less than 10% on this subject, that would simply not be good enough for me personally......

I now terminate this seemingly pointless conversation (for want of a better word!!) with you as of now. Goodbye.