Any advantage to use DC to power LED strings?

[Rogelio]

I love LEDs but I dont like the flicker of half wave.  I see full wave are sold but is there much difference between them and the inexpensive strings when used in a show?

[rimist]

I know that some people here have converted half wave to full wave with some parts, less than a dime for those parts as I recall. Hopefully we can be educated on the how, as I have many strings to "repair"

-Rimist

[Steve Gase]

There was a good discussion on this topic in LSH.  Dennis Cherry (in this forum) had a number of great points.

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[Rogelio]

Yeah converting to DC is rather simple.  Perhaps even supplying DC from the driver.  But I was wondering if there is a real advantage to it.  A little brighter maybe, but leds are already bright.  A little more current (not an advantage) but since LEDs are so much less power than incandescent, whats a few milliamps.  Most people I talk to cannot see them flicker.  A moving display would certainly benefit from full wave but what about a blinky flashy???
thanks
Roy

[Dennis Cherry]

There is a large mind set of LED flicker, just because a few people have an issue with Half wave powered LED's.

The human eye really cannot see much flicker over 10 hertz and only in your peripheral vision. so running them at 60 hertz and not moving in the breeze you should not see flicker.

I run both full and half wave and nobody has ever complained about flicker or even can tell what LED's are Full or Half wave.

So if the lights are stationary and not moving like wrapping small tree branches with half wave, you should not have problems.

[JonB256]

I am going to try to convert some "bad" AC LED strings to DC over the spring and summer. These are strings that used voltage doublers that failed, usually a bad capacitor but sometimes a diode. I have a particularly large pile of blues. 100ct strings, maybe 30 strings.

I'll try to find the right number of lights to be powered by 12 volts. Since blue tends to run between 3 and 4 volts, I'll probably cut them into groups of 4 and power them from an MR16. Seems a shame to toss them and I've already replaced them with good strings, so I don't need them as AC strings. The bigger question is how to wire them without too much wire stripping and soldering.

I've also got a lot of old half wave strings that I didn't toss out that may get converted.

I'm thinking potential Christmas Parade Float. Run the whole thing on car/truck battery power and avoid the noise of a generator. My AC controllers have never been happy on a generator. Toss in some dumb RGB ribbon strips and my RGB floods and I can at least blind the judges if not impress them.

[jnealand]

I have all kinds of LED form HD, Lowes, Big Lots, Costco, etc.  I could not tell you if they are half or full wave and I have yet to meet anyone who has looked at my display who could tell me either.  I think there may be a few people who can see this so called flicker, but when my lights are going on and off in 50ms increments to me it would sure be hard to see any flicker.  I for one do not worry about half versus full, but that is just me.  Some people do not worry about gfci for their lights either, but that is just another personal option.

[chrisatpsu]

a whetstone bridge can make your strings full wave.  it grabs both sides of the AC.

[rrowan]

Maybe the original Lynx should make a come back. 

Rick R.

[tbone321]

I think that the real issue with 1/2 wave LED is in the dimming.  If yoor display is more of the on / off style then you probably wouldn't notice much but if you actually dim the lights for any period of time then you might notice it.

[Dennis Cherry]

I think that the real issue with 1/2 wave LED is in the dimming.  If yoor display is more of the on / off style then you probably wouldn't notice much but if you actually dim the lights for any period of time then you might notice it.

Not true, dimming is dimming, the 60 hz will still be 60 hz. Only difference will be LED's dim different than incandescents.

LED's will be full on between 70-75% to your eyes and half intensity will be 15-25%. It depends on the quality of the LED's.

Fade LED's from 100% to zero and it will be have a delay and then a fast fade. Do it from 70% and the delay will be better but still a little fast. Dimming curves will improve the dimming and lower intensities.

Try it yourself using any Console Utility in your software, but do it in a dark room like your lights will be in the dark of night.  You will find your intensities changing in your display for LED's.

[chrisatpsu]

personally, when i look at half wave lights, they appear dimmer, and hurt my eyes if i look at them for more than a second.

[tbone321]

I think that the real issue with 1/2 wave LED is in the dimming.  If yoor display is more of the on / off style then you probably wouldn't notice much but if you actually dim the lights for any period of time then you might notice it.

Not true, dimming is dimming, the 60 hz will still be 60 hz. Only difference will be LED's dim different than incandescents.

LED's will be full on between 70-75% to your eyes and half intensity will be 15-25%. It depends on the quality of the LED's.

Fade LED's from 100% to zero and it will be have a delay and then a fast fade. Do it from 70% and the delay will be better but still a little fast. Dimming curves will improve the dimming and lower intensities.

Try it yourself using any Console Utility in your software, but do it in a dark room like your lights will be in the dark of night.  You will find your intensities changing in your display for LED's.

First of all, we are talking about 1/2 wave strings so it is 30 hz and there are people that can see that.  Secondly, and as you said, LED's dim differently and are fully turning on and off during the pulses, and are off more than they are on with half wave.  Because of this, the more you dim them the greater the difference is between the on and off times and to many that creates a noticeable flicker at lower dim levels.  As I said before, this is not an absolute but the full wave do dim better and some will see the difference.

[Dennis Cherry]

I think that the real issue with 1/2 wave LED is in the dimming.  If yoor display is more of the on / off style then you probably wouldn't notice much but if you actually dim the lights for any period of time then you might notice it.

Not true, dimming is dimming, the 60 hz will still be 60 hz. Only difference will be LED's dim different than incandescents.

LED's will be full on between 70-75% to your eyes and half intensity will be 15-25%. It depends on the quality of the LED's.

Fade LED's from 100% to zero and it will be have a delay and then a fast fade. Do it from 70% and the delay will be better but still a little fast. Dimming curves will improve the dimming and lower intensities.

Try it yourself using any Console Utility in your software, but do it in a dark room like your lights will be in the dark of night.  You will find your intensities changing in your display for LED's.

First of all, we are talking about 1/2 wave strings so it is 30 hz and there are people that can see that.  Secondly, and as you said, LED's dim differently and are fully turning on and off during the pulses, and are off more than they are on with half wave.  Because of this, the more you dim them the greater the difference is between the on and off times and to many that creates a noticeable flicker at lower dim levels.  As I said before, this is not an absolute but the full wave do dim better and some will see the difference.

First off the AC frequency is 60 hz, in half wave strings the LED's are turning OFF and ON 60 times a second not 30. In Full wave they are turning OFF and ON at 120 times per second. Think about it?

For dimming differences Yes there is a slight difference, that's why I mentioned you test you LED strings using a Console hardware program to get a feel for your lights, even put a couple of strings on mini's or C7's to compare the dimming.

Mu display in 2010 I had a sequence that accidentally had a 1% value on all strings instead of 0% OFF. what surprised me was the nice soft glow the LED gave to the house. Could not see any flicker at 1% on either Full or Half Wave LED's. People like the effect it gave the song.

Now not all LED's light strings will turn on at 1% it has to do with many factors which would take to long to explain and understand, but the BLUE LED's along with the RED did barely come on, but Green and White did not. So with the accident of the 1% value my display had a background glow of BLUE and was dominant over the RED. I have a video of it but my camera is not really the best for showing how it really looked.

One other thing the controller design has a lot to do with how the LED's work. The Lynx by far has a better design for LED's than the LOR or Renard designs IMHO.  The Lynx V5 already has the needed snubbers included to prevent the inductive load of the LED strings form letting the misfire of the traics from happening during fades or anytime.

The best advice is test, test, test so you know how your display will operate before the season starts.

 

[chrisatpsu]

I'm sure the quality of the manufacturers makes a difference.
I had a string from big lots ( those led strings that look like plastic globes in slices.)
As soon as I plug them in, you don't actually see them turn on and off, but you can see it pulse extremely fast. I had to take them down, bc they were driving my wife and myself nuts when we went into the room.  If they have a color to them besides white, then its not so bad, but i can tell.