LED lights and dimmer switches

[mhaze]

It's safer because you don't need to worry as much about shorts, but I don't think you're right about it requiring less copper. In fact, since many appliances would still run off of 120V AC for the foreseeable future (like vacuum cleaners, microwaves, power tools, etc), it seems like you'd need MORE copper wiring to run a parallel low-voltage system. Furthermore, the gauge of wire needed is determined by the current, not the power, and dropping the voltage will increase the current. I'd like to see a low-voltage home standard happen, and it might be worthwhile, but I doubt you're going to save on copper by doing so.

No licensed electrician required for low voltage circuits.....that could save a lot of people a lot of money.

 

[Beerina]

There's another thread where someone's getting bugeyed from his LED-backlit computer screen when he dims it, or it auto-dims.

Seems the LED doesn't actually dim -- they just strobe it at various rates to simulate various brightnesses. This leads to similar problems people used to have for old-school crappy monitors at 60 Hz.

Sounds like these dimmer bulbs are doing kind of the same game. I would like to think the ones rated for, say, 60 watt equivalency, were "full on" that bright, no more, no less, and no strobing.

 

[Furcifer]

There's another thread where someone's getting bugeyed from his LED-backlit computer screen when he dims it, or it auto-dims.

Seems the LED doesn't actually dim -- they just strobe it at various rates to simulate various brightnesses. This leads to similar problems people used to have for old-school crappy monitors at 60 Hz.

Sounds like these dimmer bulbs are doing kind of the same game. I would like to think the ones rated for, say, 60 watt equivalency, were "full on" that bright, no more, no less, and no strobing.

Isn't that just because of the refresh rate? No matter what a computer screen cycles not just because it's an LED.

I don't know about the AC bulbs, but I know the DC flashlights don't cycle, they just lower the current.

ETA- same with this remote control box, the microprocessor varies the current

 

[kookbreaker]

I bought the cheapest ones (30 LEDs instead of 60 LEDs) and they are not as bright as the 50W halogens they replaced but they are good enough to light the room. The colour of light seems fine - not harsh as I feared.

The main reason I bought them was the halogens were over heating and burning out on a very regular basis. So far the LEDs have not burnt out, although as I mentioned before one of the four bulbs I purchased only comes on at half brightness so I will see if the company will replace it. I plan to try a packet of the 60 LEDs too.

Overall I am impressed by them.

Interesting. I would love to replace the Halogens in the store with LEDs, but its not just the brightness that is a factor. The Halogens do a good job with color on products. Do the LEDs match that pretty well?

 

[jasonpatterson]

LED lighting is getting fairly common for aquarium use where it's quite popular due to the small size of the fixture and the relatively low power consumption. Many people prefer it aesthetically as well. As far as a DIY system for a house, using the high power (1-5W) LEDs requires things like heatsinks, drivers, and such that most people wouldn't think of in comparing the price. It's fairly expensive still compared to fluorescent, though it beats the pants off of incandescent lighting in the long term. There are fully dimmable drivers as well, though these probably wouldn't work with the new dimmers but would be perfectly fine with the old fashioned potentiometer versions.

There is also already a fair amount of experience/equipment in existence for 12V home systems from people who want to produce their own power and store it in batteries. It's been around for some time.

 

[Subduction Zone]

Interesting. I would love to replace the Halogens in the store with LEDs, but its not just the brightness that is a factor. The Halogens do a good job with color on products. Do the LEDs match that pretty well?

When I had my furniture store I did not like the color spectrum of fluorescent bulbs. I compromised by switching most of them to CFL's but kept a few halogen spots for color purposes. You might need to do the same where you work. Plus there are spots where accurate color reproduction are more important. For example where I had the fabric swatches for upholstery I used a bank of halogen spots. At home I still use mainly incandescent bulbs. But I figure they are greener for me than others. My house has old fashioned resistive heating and the most of the time that I use the lights the heat is on too. So energetically I consume just as much with them on as I would with CFL's or LED"s. My outside lights are CFL's since I don't see any reason to warm it up out there When I made the switch in my store I notice one big advantage. My store was not air conditioned and it was much cooler in the summer when I made the switch. It would have been even better with LED's.

 

[Furcifer]

Do the LEDs match that pretty well?

I think if you were to make a project out of it (seems appropriate given your store) you could get the proper spectrum. LED's are binned according to their temperature (voltage and flux as well) and they run pretty much the entire spectrum. It might take two high powered LED's, like 4300K and a 6000K to get the right colour but I'm sure it's possible. (I don't know much about the pre-fab stuff. They're getting better, those older ones with 40 LED's (that look like Lite-Bright pegs) are being replaced with the new SSC and CREE LED's)

There's an amazing selection of DIY LED stuff available online. You might even consider making up some DIY flashlight kits for your store. For about $20 in parts, if you've got a soldering iron you can make some surprisingly powerful flashlights. They've even got UV emitters, make your own CSI style flashlight.

 

[Finn McR]

"Considering that they'll last 25 years instead of the half year or so that 50 cent incandescents last, ..."

Either you are exaggerating, or you are buying really bad incandescent bulbs. I have a number of incandescents that that have lasted over ten years at low duty (closet lights) and others that I have only replaced 2 to 3 times in 13 years at medium duty (so call it 4 to 6 years life).

 

[tyr_13]

We carried some nice LED bulbs at my store. I was waiting for the CFLs I had to burn out to replace them. But they didn't sell quickly enough and my store manager sent them almost all away. We actually got complaints that we had LED bulbs and one guy yelling that we should only carry 'real bulbs'.

There were some specifically rated for dimming.

 

[CaveDave]

I cannot forsee any "danger" in leaving the dimmer in place, but you may be forced to use only full on or full off (not trying to dim at all).

LED lights can be dimmed, by varying the current flowing through them. I am not aware of any commercial lighting product that works in that way.

That is not how I understand it.
[Amended:Yes, but perhaps not the easiest method for domestic use...]

As was pointed out previously most light dimmers work by adjusting the duty cycle of the AC waveform presented to the device. As the mains (US) of 120v has to be stepped down to the low voltage needed for the LED it is usual to have a constant current source built into the interface.
As you turn down the dimmer, usually by changing the phase angle to a thyristor, the LED power converter copes just fine until there is insufficient energy to maintain operation. The effect will thus be: full,full,full,full,dim,off,off,off.
The angular spread of the full/dim/off transition is probably too fine for most dimmer switches.

True, as far as I can tell...

There is not a safety issue with this, by the way.

Agreed.

What is needed is a circuit that converts the average incoming supply to a variable current source for the LED.

Here we part company.
[Amended:On second thought, correct in principle, but depends on implementation.]

That is relatively trivial to implement, but I have not seen any impetus to offer that capability.

Perhaps...
I wonder why?

I have an LED ring illumination device for one of my microscopes, and I built a variable current source for it running off 12v DC. I can adjust the brightness to a fine level.

V.

I have no doubt you have forced that arrangement to work, but I have a different opinion.
[Amended:On second thought, maybe not so much]

I could be WAY off base, and "Not even wrong" (It would certainly not be the first time ), but having devoted my life to electronics, I have a different understanding (show me I'm misinformed, and I will concede):
[Amended:Before final posting, I did more thinking and researched more deeply, and I have concluded that I had "gone off half cocked"(Firearms term - not to be misconstrued as sexual innuendo), and now freely admit my mistakes, and include them (even though I have not yet sent the original, so there would have been no record if I deleted them now...)]FWIW.
IOW, I admit my error...

Normal LEDs have a threshold voltage before any significant current flows, after that point, current rapidly rises with SMALL increases in voltage, and can quickly rise to destructive levels (See also - SED [smoke emitting diode] and DED [dark emitting diode] )

From White LED Tips.

So, variable Voltage is not a Good Thing.

Now, while current control CAN work, even well, in a dedicated circuit, you would be forced (in an A/C mains-fed originally-designed-for-incandescent situation) to modify the dimmer in a way that would have to be changed again if CFL, Incandescent, or some as-yet unknown lamp-type were to be installed later

I, (were I in charge,) would design a wide-range, low-voltage circuit to put in the base of LED lamps that would respond properly to the Phase-angle-switching of old-style dimmers, and generate a PWM (pulse width modulated) constant voltage and current waveform to the LEDs that responded linearly to any dimmer input, and feed the load at the optimum efficiency point on the curve for any brightness level desired.

But that's just me...

Alternatively, I would update the primitive phase switching dimmers to a full-voltage PWM output (eminently achievable w/ today's technology) that would provide the same results on incandescent OR LED (I am not sure of CFL, but I think it would work).

(The above assumes that linearity and controllability is A Good Thing^{TM Martha Stewart}, and that adaptability also ranks high).

But that's just MY opinion... FWIW
[Amended:Most of this still holds true - I just felt I had to reiterate my change of attitude...]

{Changes in attitude, changer in latitude --- OOps, sorry folks, I am possessed by Jimmy Buffet, or at least that tune...}

-------------------


In the case at hand, my UNeducated guess, is that you can use what you've got, at least in the full on/off mode, and I can see no inherent danger to life or property, BUT I doubt that that the dimming performance will ever be satisfying.

-----------------------------

[Amended:Well, it turns out, that I was wrong in many ways, out of the gate: I COULD have escaped any embarrassment by simply deleting this entire post and erasing my foolishness forever... But I decided that there could be some lesson that, perhaps, would give a leg up to another "student" here or elsewhere, and that the scales tilted towards educational value over saving "face". Whatever, ... if ONE person gains wisdom from this, however small, then the humiliation will have been worth the price.

[SPOKEN W/ background chords]
...When everything around me, even the kitchen ceiling, has collapsed and crumbled without warning. And I am left, standing alive and well, looking up and wondering why and wherefore.
At a time like this, which exists maybe only for me, but is nonetheless real, if I can communicate, and in the telling and the bearing of my soul anything is gained, even though the words which I use are pretentious and make you cringe with embarrassment, let me remind you of the pilgrim who asked for an audience with the Dalai Lama.
He was told he must first spend five years in contemplation. After the five years, he was ushered into the Dalai Lama's presence, who said, 'Well, my son, what do you wish to know?' So the pilgrim said, 'I wish to know the meaning of life, father.'
And the Dalai Lama smiled and said, 'Well my son, life is like a beanstalk, isn't it?'
"In Held Twas In I"
Procol Harum
Shine On Brightly

[That always stuck in my memory (could it be the LSD I had just taken?) and seems to MEAN something to me, even though that is an irrational connection...]

Cheers,

Dave


Perhaps I am approaching some turning point in my life...
Perhaps the ethanol fog has overcome me...
Perhaps I am suffering with "early" onset dementia...
Perhaps none of this is real and my "Perception" of the universe is imaginary...
Whatever...


I am about to push the "Submit Reply" button, and I don't care what shame this delivers me; I will only edit for Grammar/spelling/punctuation, if at all...
Enjoy...

 

[Furcifer]

I cannot forsee any "danger" in leaving the dimmer in place, but you may be forced to use only full on or full off (not trying to dim at all).



That is not how I understand it.
[Amended:Yes, but perhaps not the easiest method for domestic use...]



True, as far as I can tell...



Agreed.



Here we part company.
[Amended:On second thought, correct in principle, but depends on implementation.]



Perhaps...
I wonder why?



I have no doubt you have forced that arrangement to work, but I have a different opinion.
[Amended:On second thought, maybe not so much]

I could be WAY off base, and "Not even wrong" (It would certainly not be the first time ), but having devoted my life to electronics, I have a different understanding (show me I'm misinformed, and I will concede):
[Amended:Before final posting, I did more thinking and researched more deeply, and I have concluded that I had "gone off half cocked"(Firearms term - not to be misconstrued as sexual innuendo), and now freely admit my mistakes, and include them (even though I have not yet sent the original, so there would have been no record if I deleted them now...)]FWIW.
IOW, I admit my error...

Normal LEDs have a threshold voltage before any significant current flows, after that point, current rapidly rises with SMALL increases in voltage, and can quickly rise to destructive levels (See also - SED [smoke emitting diode] and DED [dark emitting diode] )

From White LED Tips.
[qimg]http://www.internationalskeptics.com/forums/attachment.php?attachmentid=22385&stc=1&d=1306708031[/qimg]

So, variable Voltage is not a Good Thing.

Now, while current control CAN work, even well, in a dedicated circuit, you would be forced (in an A/C mains-fed originally-designed-for-incandescent situation) to modify the dimmer in a way that would have to be changed again if CFL, Incandescent, or some as-yet unknown lamp-type were to be installed later

I, (were I in charge,) would design a wide-range, low-voltage circuit to put in the base of LED lamps that would respond properly to the Phase-angle-switching of old-style dimmers, and generate a PWM (pulse width modulated) constant voltage and current waveform to the LEDs that responded linearly to any dimmer input, and feed the load at the optimum efficiency point on the curve for any brightness level desired.

But that's just me...

Alternatively, I would update the primitive phase switching dimmers to a full-voltage PWM output (eminently achievable w/ today's technology) that would provide the same results on incandescent OR LED (I am not sure of CFL, but I think it would work).

(The above assumes that linearity and controllability is A Good Thing^{TM Martha Stewart}, and that adaptability also ranks high).

But that's just MY opinion... FWIW
[Amended:Most of this still holds true - I just felt I had to reiterate my change of attitude...]

{Changes in attitude, changer in latitude --- OOps, sorry folks, I am possessed by Jimmy Buffet, or at least that tune...}

-------------------


In the case at hand, my UNeducated guess, is that you can use what you've got, at least in the full on/off mode, and I can see no inherent danger to life or property, BUT I doubt that that the dimming performance will ever be satisfying.

-----------------------------

[Amended:Well, it turns out, that I was wrong in many ways, out of the gate: I COULD have escaped any embarrassment by simply deleting this entire post and erasing my foolishness forever... But I decided that there could be some lesson that, perhaps, would give a leg up to another "student" here or elsewhere, and that the scales tilted towards educational value over saving "face". Whatever, ... if ONE person gains wisdom from this, however small, then the humiliation will have been worth the price.



[That always stuck in my memory (could it be the LSD I had just taken?) and seems to MEAN something to me, even though that is an irrational connection...]

Cheers,

Dave


Perhaps I am approaching some turning point in my life...
Perhaps the ethanol fog has overcome me...
Perhaps I am suffering with "early" onset dementia...
Perhaps none of this is real and my "Perception" of the universe is imaginary...
Whatever...


I am about to push the "Submit Reply" button, and I don't care what shame this delivers me; I will only edit for Grammar/spelling/punctuation, if at all...
Enjoy...

I come here for the discussion, not to read what someone else has googled. This post was obviously not googled, well at least not until it was obviously googled.

I laughed, thanks. (I think I learned something too)

 

[CaveDave]

Hmmm. . .is anyone working on a dimmable LED bulb that dims by turning off individual LEDs? I realize this wouldn't use a regular dimmer switch, but would require that stuff built into the bulb and/or fixture. However, I think the future of home lighting will involve a lot more remote control anyway. . .


Anyone know if what I'm saying is at all feasible?

Home wiring especially in older homes is always a little bit of a history lesson. Before I re-wired my entire c. 120 yr old house, I had some bits of grounded romex roughly vintage mid-'70s, some ungrounded encased wiring, and some very old knob and tube wiring. (For that matter, when I went to install light fixtures in two rooms where there hadn't been any ceiling fixtures, I found gas lines running to where very old lights used to be.)

My FIRST post was started before this appeared (post # 8 then...);

But that was sort-of what I meant in there...

Retrofitting new-tech to old-tech is always problematic...

I would propose a different approach, but the manufacturers seem to disagree... ?Que Lastema? [sp?] (What A Pity....)

That Is All.

D

 

[CaveDave]

I will respond to several posts (not directed at me) in one whack, only to save time.

If I offend sensibilities or "netiquette", I herewith apologise in advance...

If you're still running with incandescents, it's not a bad time to try out a few LED's and seeing if they work for you. But while even a $40 LED bulb can pay for itself over a lifetime compared to an incandescent, if they drop to $20 next year, you won't have saved enough money in the mean time to justify the premium. So it's still early to switch completely unless the cheaper LED's satisfy you.

If you're using CFL's and are satisfied with them, I'd say the price is definitely too high to justify switching out working bulbs, though you might consider replacing dead bulbs.

I concur.

An online retail company with a name similar to "ThinGreek" (but with an extra k and no r)* sells a $40.00 5-watt LED bulb that has dimming and color setting via a remote control. Probably not as convenient as using a wall dimmer for room lighting (especially where one wall dimmer would control several fixtures), but it might fill a need.

Respectfully,
Myriad

*Actual name concealed to conform to the new Rule 6.

Well, that will work fine, though it requires that remote...

I was hoping we could avoid that...

(BTW: Is rule 6 that onerous? I saw the announcement, but I didn't think it would forbid simple references to commercial entities. did I misunderstand?)

Very reasonable. Check out a deal extreme, it's a Chinese supplier with free shipping and just about anything you want for next to nothing. There's hundreds, maybe thousands of LED products, anywhere from single LED turn signal lights to multi-die LED flood lights.

If you're inclined to tinkering it's amazing what you can do with LED's. I purchased a 12V IR remote control unit for $6. It's designed for use with these RGB LED strips but works with any 12V LED light. It has a multi-function strobe, flash, fade and dimmer. With that and a little conductive paint I've made some remote controlled poster/painting lights that are virtually invisible.

The CREE LED's, the ones they use in flashlights, are extremely efficient and extremely bright, a 5mmx5mm LED puts out 1000 lumen at 3000ma and is rated for some 100 000 hours.

I'm speculating, but I can imagine in the not too near future AC lighting will be a thing of the past. I can see a separate 12V or 3V DC system emerging dedicated to lighting and perhaps computers and peripherals. It's safer and requires a lot less copper wiring.

Nice points.

It's actually rather easy to dim individual LED bulbs, and to do so in a continuous and well-controlled manner. The problem is that you really want to do that with separate electronic controls while keeping the line voltage unchanged, and you can't do that through an Edison socket with only two connections. There are ways around that, but they would be more expensive. For example, you could simply put a radio receiver in each bulb, and a radio controller as either a remote or possibly built into the wall. In fact, such a thing already exists:
http://www.amazon.com/Multi-Color-E...ZSEG/ref=sr_1_1?ie=UTF8&qid=1306712365&sr=8-1
It's a multi-color LED bulb with a remote control to adjust color AND brightness, as well as a few effects like strobe. I don't know what the cost premium would be for adding this to standard LED bulbs, though, so that might be a problem.

What (S)He Said...

It's safer because you don't need to worry as much about shorts, but I don't think you're right about it requiring less copper. In fact, since many appliances would still run off of 120V AC for the foreseeable future (like vacuum cleaners, microwaves, power tools, etc), it seems like you'd need MORE copper wiring to run a parallel low-voltage system. Furthermore, the gauge of wire needed is determined by the current, not the power, and dropping the voltage will increase the current. I'd like to see a low-voltage home standard happen, and it might be worthwhile, but I doubt you're going to save on copper by doing so.

Ditto...

I'm just thinking you don't need to run AC in the ceiling.

Like all the fluorescent lights in the ceiling, replaced with multi-die CREE's running off tiny 2 wire DC? You'd never have to change them.

That can all be done with 2 wire 16 gauge probably.

Just thinking outside the box here.

Still requires wires, but i agree on safety and cost part...
The reality is that existing structures were set up for (say) 120/240 V 15-20 A
and only massive retrofit and/or new construction can take full advantage...

Really good concept, though.

I bought the cheapest ones (30 LEDs instead of 60 LEDs) and they are not as bright as the 50W halogens they replaced but they are good enough to light the room. The colour of light seems fine - not harsh as I feared.

The main reason I bought them was the halogens were over heating and burning out on a very regular basis. So far the LEDs have not burnt out, although as I mentioned before one of the four bulbs I purchased only comes on at half brightness so I will see if the company will replace it. I plan to try a packet of the 60 LEDs too.

Overall I am impressed by them.

Cool.

Yeah, that sounds like a defect. Hope they stand up for their product.

No licensed electrician required for low voltage circuits.....that could save a lot of people a lot of money.

[GGRRrrr- grumble- spit-spit]
"We Don't Need No Steenking LICENCES!!!!!"
[I am that guy that "spiked" over 95% on the PD scale of the MMPI...]

There's another thread where someone's getting bugeyed from his LED-backlit computer screen when he dims it, or it auto-dims. Seems the LED doesn't actually dim -- they just strobe it at various rates to simulate various brightnesses. This leads to similar problems people used to have for old-school crappy monitors at 60 Hz.

Sounds like these dimmer bulbs are doing kind of the same game. I would like to think the ones rated for, say, 60 watt equivalency, were "full on" that bright, no more, no less, and no strobing.

If a proper choice of switching frequency is made, no animal eye (human or other) could possibly notice the flicker. LEDs are fast enough that duty cycling of 1 kHz (1000 / sec) are no problem.
Could this person have either an extremely-poorly designed (such as when they might have clocked from the refresh clock, to save on another oscillator), or it COULD be a defective unit where the clock is running at some incorrect - lower - rate than designed?

Isn't that just because of the refresh rate? No matter what a computer screen cycles not just because it's an LED.

True that, but I can imagine cost-cutting measures locking the backlight duty-cycle clock to the refresh clock... Not that it is LIKELY (or desirable), but sometimes managers force weird choices on engineers...

[OK, you managers are ALSO free to attack me now.]

I don't know about the AC bulbs, but I know the DC flashlights don't cycle, they just lower the current.

ETA- same with this remote control box, the microprocessor varies the current

Have you observed the current w/ an oscilloscope? Even with a modern DMM, it can be tricky to distinguish a variable (read "analog") voltage or current from the High-Speed (>, say 1000/sec) duty-cycled rectangular wave ("Digital", so called). (this is a point I have beaten my head against the wall trying to educate "traditional" {automotive and otherwise} technicians on for many years -- proper measurement results FUNDAMENTALLY rely on understanding what it is you want to measure!)
Yes, average current IS varying, but at finer time-slicing, it is only on or off w/ a fixed high/low range.

Also, some "DC" LED flashlights are anything but... I have one in my pocket w/ a high efficiency white LED that requires only a single AA (1.5 V) cell...
How, one might ask, does a 1.5 volt source drive a diode that only starts to conduct around 3 v.? Good question...
The answer is that there is a tiny circuit attached to the base of the LED - (less than 1 cm3) with a tiny inductor (coil of wire on a ferrite core), a transistor, and a few passives (capacitors and resistors) that make up a self-starting BOOST switching power supply capable of reaching the threshold voltage and giving sufficient current even when the battery (correctly "cell") drops to startlingly less than 1 v without noticeable loss of brightness. Startling...
)

Interesting. I would love to replace the Halogens in the store with LEDs, but its not just the brightness that is a factor. The Halogens do a good job with color on products. Do the LEDs match that pretty well?

Halogen lamps, being a type of incandescent, (as opposed to "metal halide")
have a "continuous" spectrum -- virtually every possible visible "color" is emitted in a smooth continuum; LEDs (in-the-raw), emit in a narrow blue-violet band, and the finished device includes some chemicals (phosphors)
Here from White LED Tips:

LEDs are monochromatic (one color) devices. The color is determined by the bandgap of the semiconductor used to make them. Red, green, yellow and blue LEDs are fairly common. White light contains all colors and cannot be directly created by a single LED. The most common form of "white" LED really isn't white. Its an Indium Gallium Nitride blue LED coated with a phosphor that, when excited by the blue LED light, emits a broad range spectrum that in addition to the blue emission makes a fairly white light. The actual light has a blue cast and is similar in color to a mercury vapor street lamp. On the curve shown, the peak at the left is the shortest wavelength blue light from the LED. The lump of emission to the right is the longer wavelength emission of the phosphor. There are other types of "white" LEDs that are made from several different LED chips of different colors assembled into one package. These have not been particularly successful as they tend to change color depending on viewing angle and their color balance is not real good at best.

And this spectrum chart:

This boils down to: color rendering (to the eye, film, or otherwise) may be disappointing at best, and horrid at worst...

YMMV

LED lighting is getting fairly common for aquarium use where it's quite popular due to the small size of the fixture and the relatively low power consumption. Many people prefer it aesthetically as well. As far as a DIY system for a house, using the high power (1-5W) LEDs requires things like heatsinks, drivers, and such that most people wouldn't think of in comparing the price. It's fairly expensive still compared to fluorescent, though it beats the pants off of incandescent lighting in the long term. There are fully dimmable drivers as well, though these probably wouldn't work with the new dimmers but would be perfectly fine with the old fashioned potentiometer versions.

There is also already a fair amount of experience/equipment in existence for 12V home systems from people who want to produce their own power and store it in batteries. It's been around for some time.

Yes. Thank you for that!

I think if you were to make a project out of it (seems appropriate given your store) you could get the proper spectrum. LED's are binned according to their temperature (voltage and flux as well) and they run pretty much the entire spectrum. It might take two high powered LED's, like 4300K and a 6000K to get the right colour but I'm sure it's possible. (I don't know much about the pre-fab stuff. They're getting better, those older ones with 40 LED's (that look like Lite-Bright pegs) are being replaced with the new SSC and CREE LED's)

There's an amazing selection of DIY LED stuff available online. You might even consider making up some DIY flashlight kits for your store. For about $20 in parts, if you've got a soldering iron you can make some surprisingly powerful flashlights. They've even got UV emitters, make your own CSI style flashlight.

BEWARE: Color rendering in a retail "store" might be iffy if you normally use incandescent (or halogen - even hotter{whiter} color temp). There can be all variety of "subjective" reactions, and I doubt "everyone" would see things the same way...

If you sell stuff based on color perception, I would run from fluorescent, CFL, LED, or any irregular-spectral lighting FAST, or have a "sunlight" area for customers to look at things in.

We carried some nice LED bulbs at my store. I was waiting for the CFLs I had to burn out to replace them. But they didn't sell quickly enough and my store manager sent them almost all away. We actually got complaints that we had LED bulbs and one guy yelling that we should only carry 'real bulbs'.

There were some specifically rated for dimming.

Thems da breaks!

Cool that they were dim-able, though.

Cheers,

Dave

 

[Furcifer]

Still requires wires, but i agree on safety and cost part...
The reality is that existing structures were set up for (say) 120/240 V 15-20 A
and only massive retrofit and/or new construction can take full advantage...

Really good concept, though.

I guess we'll see how it goes soon enough. Having tinkered with these LED's recently I've got to say they are the way to go. They're small, light weight, extremely efficient, extremely bright, practically indestructible, last forever, have infinite shelf life, and safe (assuming you don't stare into them). The only drawback is that they run on DC (they also get hot, but that's too be expected given they are essentially concentrated light). I'm guessing that their advantages will be a big enough push to get us into a low voltage infrastructure in the near future.

True that, but I can imagine cost-cutting measures locking the backlight duty-cycle clock to the refresh clock... Not that it is LIKELY (or desirable), but sometimes managers force weird choices on engineers...

[OK, you managers are ALSO free to attack me now.]

Beyond my current level of expertise.

Have you observed the current w/ an oscilloscope? Even with a modern DMM, it can be tricky to distinguish a variable (read "analog") voltage or current from the High-Speed (>, say 1000/sec) duty-cycled rectangular wave ("Digital", so called). (this is a point I have beaten my head against the wall trying to educate "traditional" {automotive and otherwise} technicians on for many years -- proper measurement results FUNDAMENTALLY rely on understanding what it is you want to measure!)
Yes, average current IS varying, but at finer time-slicing, it is only on or off w/ a fixed high/low range.

No, just my trusty DMM. I'm saving up for an oscilloscope.

I have noticed the LED's seem to "twinkle" when I use the microprocessor controller to dim them. I'm not sure if this is a result of the voltage fluctuation, the refraction through the plastic or if it's possibly the duty cycling.

Also, some "DC" LED flashlights are anything but... I have one in my pocket w/ a high efficiency white LED that requires only a single AA (1.5 V) cell...
How, one might ask, does a 1.5 volt source drive a diode that only starts to conduct around 3 v.? Good question...
The answer is that there is a tiny circuit attached to the base of the LED - (less than 1 cm3) with a tiny inductor (coil of wire on a ferrite core), a transistor, and a few passives (capacitors and resistors) that make up a self-starting BOOST switching power supply capable of reaching the threshold voltage and giving sufficient current even when the battery (correctly "cell") drops to startlingly less than 1 v without noticeable loss of brightness. Startling...)

Conversely they also use a buck driver, which drops the voltage down to the typical 3-3.7V most of these LED's run at. All in a 17mm PCB pill. Between these and the Li-po batteries you can basically pack the lighting from a 70's disco into a lunch box.

If you sell stuff based on color perception, I would run from fluorescent, CFL, LED, or any irregular-spectral lighting FAST, or have a "sunlight" area for customers to look at things in.

lol, yes, not recommended if you're selling paint.

kookbreaker's got a science/educational supply store. I think it's virtually essential that he has some LED's in the store. They're almost as cool as lasers but more practical.

 

[CaveDave]

I come here for the discussion, not to read what someone else has googled. This post was obviously not googled, well at least not until it was obviously googled.

I laughed, thanks. (I think I learned something too)

I separated your post from that last "batch" response, because I felt it deserved a separate response. Besides, the others were "general" posts, whereas this one came specifically for me.

OK - Let me say from the "git-go", that I NEVER (to the best of my recollection) want to post anything, that if it were said in a face-to-face situation, would potentially provoke the other participant (you, in this instance) into anything more than a passionate, but civilized debate.

Now, that said, I know you (and I believe the reciprocal is true), ONLY by virtue of these fora, and I don't recall ever having any direct exchanges with you (although I remember seeing many of your posts, and, I assume, you may have been aware of me. (You are invited to correct me on any statement you believe is wrong,)

Honestly, I am baffled (and to an extent, troubled), by your particular choice of words (mostly centered on "Google".

Now, honestly? did I use Google? Of course I did... There are possible alternatives, but I did use it. Have I somehow sinned against nature, in your opinion?
You posted:

I come here for the discussion, not to read what someone else has googled. This post was obviously not googled, well at least not until it was obviously googled.

I laughed, thanks. (I think I learned something too)

OK, [HEADSMACK, Squared...DOH!!) now that I pasted the quote again, and after Re-re-re-re-reading it, I conclude that I misjudged... I had somehow failed to absorb the "grin" emoticon (I still don't know how that slipped past...).
If that is actually how you intended to present (friendly/teasing) then I owe you an apology: I totally "jumped naked", to use a former co-worker's idiom, at that. I chalk it up to fatigue, ethanol, and hypersensitivity (is it yet obvious that I am a "troubled" individual?)

Boy, do I feel STOOOOPIDDD!!

----------------

Anyhoo - in the spirit of my other post, I will let my errors stand -- undeleted and naked for the world to see, as ashamed as I am for being too SLOW to snap to (what I now believe be) your joke.

Again, this will remain as a (hopefully) useful lesson to someone else, and perhaps they will read this and realize that they are not the stupidest human being on the planet.

Or, I will settle for just allowing everyone a good belly-laugh, on me...

Cheers,

Dave

PS - I choose to let this post stand as is to illustrate a real-time / real-life example of how easy it is to misunderstand / misinterpret another -anonymous- person's postings, and make assumptions about their intentions
( of course, since I have NOT YET posted this, and I have no 'certainty' that indeed my "2nd take" is the correct one, I could be full of ..."stuff"...so be it...

Call this CaveDave embarrassing himself in Public,
Call this a train wreck,
Call this shameful,
Call this performance art, if you choose.

It wasn't PLANNED,
It wasn't SCRIPTED,
It wasn't Asked For,
SOME may wish they had never been subjected to the indignity...

I only hope 1 person learns by (negative) example...................

 

[CaveDave]

3bp: (if I may be so informal)
Just finished responding to your last post. (You will see it -- and my glaring... whatever...

I guess we'll see how it goes soon enough. Having tinkered with these LED's recently I've got to say they are the way to go. They're small, light weight, extremely efficient, extremely bright, practically indestructible, last forever, have infinite shelf life, and safe (assuming you don't stare into them). The only drawback is that they run on DC (they also get hot, but that's too be expected given they are essentially concentrated light). I'm guessing that their advantages will be a big enough push to get us into a low voltage infrastructure in the near future.

I agree with that...(except I don't get the hazzard part... unless you mean in the same way that ANY bright, concentrated source, could, at least temporarily, cause 'fatigue" of rods and cones. so they have to slowly recover

Beyond my current level of expertise.



No, just my trusty DMM. I'm saving up for an oscilloscope.

I have noticed the LED's seem to "twinkle" when I use the microprocessor controller to dim them. I'm not sure if this is a result of the voltage fluctuation, the refraction through the plastic or if it's possibly the duty cycling.

Of course, since I wasn't there, I can't say for certain what the "twinkle" is, but you could have sensitive eyes, the rep rate may be relatively low due to software design, or the clock may be running slower than assumed by the programmer (I am leaping to the assumption that this may have been a "pre-designed" setup - like a kit)

If so, are you sure that the clock rate is at design spec?
If you wrote the lamp drive routine, did you calculate cycle times (i assume there is a loop in control), or is it one of those fancy micros with the timers, counters, PWMs, etc?

I, too, LUST after a good 'scope -- what I have is a P.O.S. (piece of s....)2 ch single timebase 5 MHz Heathkit i got 4th (or more) hand, that may have enough dust in the switches to stop it completely -- last time 1 ch dead, other dodgy,

Other than that, I have a "graphical multimeter" that only WISHES it could be a 'scope when it grows up!

Conversely they also use a buck driver, which drops the voltage down to the typical 3-3.7V most of these LED's run at. All in a 17mm PCB pill. Between these and the Li-po batteries you can basically pack the lighting from a 70's disco into a lunch box.

What does? I must ha gotten left behind, somewhere. Do you mean the microcontroller.

Got a brand name and part # so I can follow along?

lol, yes, not recommended if you're selling paint.

kookbreaker's got a science/educational supply store. I think it's virtually essential that he has some LED's in the store. They're almost as cool as lasers but more practical.

I bet you could "simulate" a wet hornet's nest by installing LEDs at e department store's makeup counter or women dept fitting rooms!

Cheers,

Dave

 

[kookbreaker]

kookbreaker's got a science/educational supply store. I think it's virtually essential that he has some LED's in the store. They're almost as cool as lasers but more practical.

I do. But they are just component parts. I don't exactly sell a huge number of them.

 

[Furcifer]

3bp: (if I may be so informal)
Just finished responding to your last post. (You will see it -- and my glaring... whatever...

I'm not a nic nazi so feel free. If I had to write my username that's what I would use.

I agree with that...(except I don't get the hazzard part... unless you mean in the same way that ANY bright, concentrated source, could, at least temporarily, cause 'fatigue" of rods and cones. so they have to slowly recover

They are bright. Not laser bright, but bright enough to do damage. The warnings on the package are to be taken seriously. Trust me it hurts in a weird "Oh, that wasn't good" kinda way.

Of course, since I wasn't there, I can't say for certain what the "twinkle" is, but you could have sensitive eyes, the rep rate may be relatively low due to software design, or the clock may be running slower than assumed by the programmer (I am leaping to the assumption that this may have been a "pre-designed" setup - like a kit)

If you google "LED IR remote RGB strip" you'll find it. I'd link it but I don't know about the new forum rules and what not. It's just a little PCB inside with a few chips on it. I've opened it up and there's not much to it.

If so, are you sure that the clock rate is at design spec?
If you wrote the lamp drive routine, did you calculate cycle times (i assume there is a loop in control), or is it one of those fancy micros with the timers, counters, PWMs, etc?

Not me, I just modified it a bit to work with a different power supply. Nothing near as complex as you're thinking.

What does? I must ha gotten left behind, somewhere. Do you mean the microcontroller.
Got a brand name and part # so I can follow along?

The flashlights. They use buck/boost drivers depending on the battery set-up. If you're running 3x18650 Li-po in series you need a buck driver for all the LED's on the market, I don't think anyone of them can handle the 16.6V from fully charged batteries.
Almost all of the drivers come with a microcontroller that handle the modes, low,medium,high, strobe, SOS or some combination therein. There are a few drivers that have 16 or 20 functions. As far as I know they vary in the percentage of the current to the LED. Basically on one mode low is 10%, medium is 20% and high is 100%, on another mode low is 5%, medium is 40% and high is 100%.
So dimming on the flashlights is handled by separate modes. There's only a few flashlights that have a built in resistor? that allows for typical resistance dimming (I think I have that right)
But, from what I gather you can use the same high power LED's for residential lighting as well. You can either go with a direct drive, or you can use a buck driver and an LED. I think however in residential lighting with multiple LED's you would have to go with a direct drive and use a variable power supply. Otherwise I don't think you can use the driver as a dimmer, there's no way to access the modes

Clear as mud?

I bet you could "simulate" a wet hornet's nest by installing LEDs at e department store's makeup counter or women dept fitting rooms!

Cheers,

Dave

lol, I admitted in another thread on CFL's that I refused to have one in the bathroom. Nothing like waking up to a green and purple monster every morning. When my last incandescent burned out I gave in a put a CFL in the bathroom. I'm getting used to it.
I honestly believe however that the new LED's are much better. I'm curious how they would compare but haven't seen anything yet.

 

[Furcifer]

I do. But they are just component parts. I don't exactly sell a huge number of them.

Those are the old ones, they look like the ones I'm using as lights in my speedometer. I think one of those SMD's puts out about 20 lumen. The new XM-L puts out 1000 lumen and the SST-90 something like 2200.

Of course they draw 3A and 5A respectively. I think the LED's you've got there draw less than 0.1A.

ETA: (Oh yah, you gotta get some of those 1" neo magnets. You know the ones that can't physically be separated if they ever came in contact, the ones that they warn you not to handle if there's any metal in the room. )

ETAA: Never mind, I see you have a 1" N35 neodymium cube, that's dangerous enough. Can you mail those to Canada?

 

[tyr_13]

Thems da breaks!

Cool that they were dim-able, though.

Cheers,

Dave

Well the flaw in my plan was waiting for my CFL's to 'burn out'. They haven't in almost five years now. The only ones that have are the ones directly above the bathroom sink.

I did buy a two pack of the cheaper ones and replaced the dimmers over my bed with them. They weren't rated for dimming, but they do, and they aren't very bright. But I knew that because the packaging told me.

EDIT: My tactical LED flashlights are still working, and still extremely bright (blindingly so, which is the point). I did have to replace the batteries, but that's because the batteries got old in some of them.