LEDs and LOR

[chowell]

A couple of weeks ago a few of us posted about LEDs working with LOR. I asked if the Energy Star brand that Sam's Club is selling can work with LOR. Someone mentioned something about a certain piece present on the lights. I just looked at the lights last night and noticed a piece that sits between the first and second bulb in the strand. It is a piece of plastic about 1.5-2" or so and obviously houses something. Is this the piece that was referred to that makes these work with LOR? Just wondering if anybody else has input. I was hoping to find out if they work without actually having to connect everything first but if so I will.

Thanks in advance.
Corey

[John Hertig]

chowell wrote:

A couple of weeks ago a few of us posted about LEDs working with LOR. I asked if the Energy Star brand that Sam's Club is selling can work with LOR. Someone mentioned something about a certain piece present on the lights. I just looked at the lights last night and noticed a piece that sits between the first and second bulb in the strand. It is a piece of plastic about 1.5-2" or so and obviously houses something. Is this the piece that was referred to that makes these work with LOR? Just wondering if anybody else has input. I was hoping to find out if they work without actually having to connect everything first but if so I will.

Thanks in advance.
Corey

It may be, but I have heard of a company which puts 'fake' rectifiers in their string. Look for 'full wave' on the packaging somewhere. The rectifier (which make it 'full wave' instead of 'half wave') 'folds' the bottom half of the power wave form. Note that this does not affect LOR; it generally makes the string brighter and have less flicker (than half wave which is 'dead' for half each cycle).

Most any LED string will work with LOR. The problem is that some won't fade well (or at all). It seems that this mostly is the case with screw in LED bulbs

[Paul C]

Hello all,

If you shake a couple of the lights in a LED stand, in a dimly lit room, you will notice a series of dashes or dots that they emit. dots being half wave, dashes being full wave. Dashes will be longer than the bulb is wide. Oh good luck with this standing in your local Walmart.

[Richard Hamilton]

Paul C wrote:

If you shake a couple of the lights in a LED stand, in a dimly lit room, you will notice a series of dashes or dots that they emit. dots being half wave, dashes being full wave. Dashes will be longer than the bulb is wide. Oh good luck with this standing in your local Walmart.

Yo Paul, I think you probably know what I am about to say, but other readers may mis-Interpret your comment.

Shaking of an LED does not cause it to do emite light any differently than when it is in a resting state. What Paul is referring to is the fact that your peripheral vision (the rods) will more readily detect flickering if the object is moving. Thus waving an LED makes this flickering appear more pronounced. In fact, flickering is easier to spot if you don't look directly at the LED, but instead, wave it off to the side of your vision.

Most folks won't see any flickering on a full-wave rectified LED.
Note, for reasons too complex to explain here, I'll just say that 20% of the population won't notice any difference when waving an LED regardless if it is half or full-wave rectified, so it is not a fool-proof method.

The box will usually say if the LEDs are full-wave rectified because marketing folks love to brag about the fact that they put more money into the manufacturing of the string.

[Paul C]

Correct Sir. what do you know about some strings of LEDs corroding prematurely. I would like to use LEDs but have read some real horror story's.

[Richard Hamilton]

Paul C wrote:

Correct Sir. what do you know about some strings of LEDs corroding prematurely. I would like to use LEDs but have read some real horror story's.

Howdy,
Well, it might be worth starting another posting thread about "LED Corrosion" since we are talking about a new topic. There are lots of smart people on here with experience at that when they see your new post. I'll be sure to reply with my experience on that during the last 4 years.

[chowell]

I originally posted this question so I thought I would let everyone know I did a test last week and the Energy Savings LED's from Sam's Club do indeed work fine with LOR. They performed all the functions just fine.

[J Warren]

Just thought you would like to know:

Did some testing of these same LED lights from Sams club and found that their are 6 of these pieces of plastic about 1.5-2" or so. The strand appears to consist of three 30 led groups with 2 pieces of plastic about 1.5-2" or so in each group of 30 configured in parellel. I removed the plastic and found that it was hidding a 750 ohm 1/2 watt resistor. I could not find any diodes of any kind. It appears that they are using the LEDs like a diode. Also if one led goes out that group of 30 goes out. :X Otherwise the price was right and they do work.

[Richard Hamilton]

John Warren wrote:

It appears that they are using the LEDs like a diode. Also if one led goes out that group of 30 goes out. :X Otherwise the price was right and they do work.

Uh, well, LEDs are in fact diodes. Like most strings of normal incandescant lights, the LEDS are in series, so if you remove one of them, the others go out in that group. However, unlike most standard incandescant bulbs, a string of LEDs will rarely go out if an LED fails. In a standard bulb, the filament breaks, but LEDs don't fail in that manner.

[Westport Lights]

LED stands for Light Emitting Diode

[Dennis Cherry]

John Warren wrote:

Just thought you would like to know:

Did some testing of these same LED lights from Sams club and found that their are 6 of these pieces of plastic about 1.5-2" or so. The strand appears to consist of three 30 led groups with 2 pieces of plastic about 1.5-2" or so in each group of 30 configured in parellal. I removed the plastic and found that it was hidding a 750 ohm 1/2 watt resistor. I could not find any diodes of any kind. It appears that they are using the LEDs like a diode. Also if one led goes out that group of 30 goes out. :X Otherwise the price was right and they do work.

i have posted that some LED's that have the bulge may not be Full Wave Rectifiers. What some manufacturers do is add additional dropping resistors to compensate for the remaining voltage in the LED string. Normally there are two resistors one on each end of each 30 LED string.

If figures out as 30 x 3.5V = 105 Volts across each of the 30 light strings.

The remaining voltage form your outlets has to be applied to a resistor.

So 120V - 105V = 15 volts.

The current lets say is 10 milliamps then:

15V / .02 ma = 1500 ohms. Divide that in half and you got two 750 ohm resistors.

LED's are diodes so you are still only turning the LED's on 60 times a second and not like a full wave string which will turn the LED on 120 times a second.

The LED's are just like the one I found at Big Lot's a couple of months ago.

[Richard Hamilton]

Dennis Cherry wrote:

LED's are diodes so you are still only turning the LED's on 60 times a second and not like a full wave string which will turn the LED on 120 times a second.

Dennis, I understand and agree with everything you said except the flicker rate. Isn't it incorrect to say that half-wave is 60 times a second? An AC line frequency is 60 Hz, and half wave would be 30 times per second and full-wave would be 60 times per second? When you think about it, that makes sense because the perception rate of most people is roughly 30 frames per second and that is why peopleperceive flicker with half-wave LEDs, but mostly never perceive flicker on full-wave. At least this is the way I learned it in electronics engineering.

[Dennis Cherry]

Richard Hamilton wrote:

Dennis Cherry wrote:

LED's are diodes so you are still only turning the LED's on 60 times a second and not like a full wave string which will turn the LED on 120 times a second.

Dennis, I understand and agree with everything you said except the flicker rate. Isn't it incorrect to say that half-wave is 60 times a second? An AC line frequency is 60 Hz, and half wave would be 30 times per second and full-wave would be 60 times per second? When you think about it, that makes sense because the perception rate of most people is roughly 30 frames per second and that is why peopleperceive flicker with half-wave LEDs, but mostly never perceive flicker on full-wave. At least this is the way I learned it in electronics engineering.

Since the frequency is 60 cycles, one cycle is both positive and negative pulses, half wave only clips off either the positive or negative pulses, so it still is 60 cycles.

Full wave takes both the positive and negative pulses and converts then to either positive pulses or negative pulses according to how design your circuit, now you will have 120 pulses and not 60 pulses

[Richard Hamilton]

Ah yes, of course. I must be getting too old for this :shock:

[Dennis Cherry]

Richard Hamilton wrote:

Ah yes, of course. I must be getting too old for this :shock:

If your memory is still good, that was one of the trick questions on the exam.

[Richard Hamilton]

Dennis Cherry wrote:

Richard Hamilton wrote:

Ah yes, of course. I must be getting too old for this :shock:

If your memory is still good, that was one of the trick questions on the exam.

Uh, that was 31 years ago at Stanford, and I was drunk from parties! I stopped being a "real" engineer two decade ago. I'll just depend on you

[Rafter Bar R]

Okay, now how hard is it to add a full wave rectifier to a string of LED's? I have found FWB LED strings at small town hardware stores while the big name box stores sell the overpriced cheap half wave strings.

[lleibeck]

I purchased some LED C9 from Target. The colors are truer than non LED but they are not near as bright. I set up a string of each and surveyed my neighbors. The vote, incandescent brightness over LED true color. Is there a brand of LED that are as bright?