Big lots LED Xmas lights

[eljefino]

This explains why they have a slight flicker when one pans their head quickly:

They're single wave rectified, and only "on" half the time with our 60 Hz AC.

Camera set to 1/15 second and whip panned. White light is traditional incandescent.

 

[beast3300]

Explain for those that only took Physics 1 and 2 about 4 years ago please.


edit nevermind, I get it now.

 

[Radman]

How about a still pic instead on a pan?

 

[chevrofreak]

I hate LED Christmas lights because of the flickering, so if these flicker half as fast......

 

[PandaBear]

I wonder if any of them use a power supply that provide a constant, non flickering light instead of half rectifier like the one show.

 

[cchase]

Every set of LED lights I've ever seen from the cheapest to most expensive have a 60 cycle flicker. It drives my eyes nuts and makes it difficult for me to drive near large concentrations of them. Very annoying.

 

[cchase]

Originally Posted By: Radman
How about a still pic instead on a pan?


The picture is meant to show the on/off flicker. A still shot would not show the flicker.

 

[xxch4osxx]

I like the look of LED christmas lights, plus they are alot cheaper to use!

 

[eljefino]

Originally Posted By: xxch4osxx
I like the look of LED christmas lights, plus they are alot cheaper to use!


Yeah the colors really pop, especially the blues.

When I have power outages I use a string of white LED lights running off my generator wrapped around my staircase railing as "emergency lighting". It's only a couple watts, and there's a female plug at the other end if I need it for whatever.

 

[Quest]

Originally Posted By: PandaBear
I wonder if any of them use a power supply that provide a constant, non flickering light instead of half rectifier like the one show.


For direct connection to AC120V (60Hz) type of LED lights, consider using a step up (12VDC to 120VAC square wave) convertor that converts in the 10s of kHz...you won't see the 60Hz 1/2 flicker.

Q.

 

[Vikas]

I hate Cadillac brake light

 

[daves87rs]

Nice...

 

[calvin1]

Is there any chance of grafting in two diodes to get the other half of the cycle?

EDIT: or maybe a cap to fill the space a little?

 

[chevrofreak]

Originally Posted By: Vikas
I hate Cadillac brake light


So do I. Late at night a couple years ago I was driving home, fairly tired, and a Cadillac pulled out infront of me. The pulsing on those tail lights caused me to see 7 sets of blurry lights as they were coming into my lane, and I felt like I was about to have a seizure!

I think PWM/PFM for tail lights should be illegal.

 

[PandaBear]

Originally Posted By: calvin1
Is there any chance of grafting in two diodes to get the other half of the cycle?

EDIT: or maybe a cap to fill the space a little?


It depends on how they are wired together. Each diode usually drop 0.7-1.2V (depends on what material it is), and if you wire 100-170 of them in series, you would not need any transformer. If they have a parallel but opposite direction series of LED string together, then either one or the other will be on at 60Hz.

If this is the case, putting a capacitor or making the supply source DC will make 1 of the string on 100% of the time, and the other string will never turn on. If this is the case, there is nothing you can do to reduce the flicker, unless you use something like a function generator to make them switch VERY fast. Function generator is very expensive and I'd imagine it is not worth the effort for holiday decoration for the electricity saved compare to regular bulbs.