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Led Flicker


Brad Bilger

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Ok.. I'm back.. been gone for a year or so. Brief History. I work part time at a large amusement park and for about 5 years I ran a LARGE show at the front gate. Last year, there were some... Ahem... Creative differance and I didn't run my LOR show. The replacement show bombed.. heh heh heh.. So now I'm back in another part of the park. So I am already hanging lights for my new show.. and the boss wants everything in my show to be LED's.

I've started with a LARGE oak tree in the center of my area. One controller mounted in tree. Each branch going to be separate channel. Running into a problem with dimming.

Initial sections:

Controller ---- Lights---Lights---Lights--- Lights---Lights All dim ok. No flicker

Finish bottom of tree. Moving upward. Now running:

Controller---25'Ext Cord---Lights---Lights---Lights---Lights

NOW I have a BAD flicker problem on just the channel with the ext cord.

Change cords. Flicker. Change Lights. Flicker. Change Channels. Flicker.

Remove cord. Replace with string of LED's. NO FLICKER.

Why would a 25' extention cord cause problems?? Cord is 14/3 sealed fresh from Home Depot.

Really need to solve problem cause I got a LOT of lights that need cords.

NOTE to Dan: I you think way back, this is the same problem that I had several years ago with my leaping arches. Same flicker and they were LED's that were on ext cords. I thought that I was having a problem with the ELL's hanging up.

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This is what I would try first (If you can at the park)....

Christmas Lights use a two prong plug so the ground wire in the extension cord is not used. You get some of those adapters that go from 2 prongs to 3 prongs and then plug that adapter into the controller, then the extension cord into the adapter.

In effect you are snipping off the ground prong (round pin) on the plug. Now this should make no difference because the ground is not being used by the load BUT in many cases this gets rid of the flicker!


Edit: This is being done on the outputs (the dangles) not on the input cords. The ground is required on the inputs to ground the metal box.


Dan

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Ok.. will give that a try.. When I get back. Leaving on Saturday for Vacation in Colorado for a week. The bug can wait until I get back.. I need cooler air and lower humidity for a while.. Hard to get into the swing of hanging Christmas lights when the outside temperature is hanging around 97 degrees. LOL.. Thanks Dan.. I'll let you know how the experiment goes when I get back..

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Brad Bilger wrote:

... Hard to get into the swing of hanging Christmas lights when the outside temperature is hanging around 97 degrees...

It will be 0C or 32F in Edmonton this weekend! Might even get snow!


It's beginning to look a lot like Christmas!!!
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PaulXmas wrote:

Brad Bilger wrote:
... Hard to get into the swing of hanging Christmas lights when the outside temperature is hanging around 97 degrees...

It will be 0C or 32F in Edmonton this weekend! Might even get snow!


It's beginning to look a lot like Christmas!!!

Actually Paul -4C (25F) in Edmonton tonight and it might be a bit cooler where I live. Maybe we will see snow flurries.
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lightzilla wrote:

PaulXmas wrote:
Brad Bilger wrote:
... Hard to get into the swing of hanging Christmas lights when the outside temperature is hanging around 97 degrees...

It will be 0C or 32F in Edmonton this weekend! Might even get snow!


It's beginning to look a lot like Christmas!!!

Actually Paul -4C (25F) in Edmonton tonight and it might be a bit cooler where I live. Maybe we will see snow flurries.

Don't tease me like that.. North Texas.. 97 degrees today was cooler than a few weeks ago.. we were hitting 109 degrees with a heat index of 123 Degrees. I work in First aid at the park and believe me.. WE WERE BUSY :shock:
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lightzilla wrote:

PaulXmas wrote:
Brad Bilger wrote:
... Hard to get into the swing of hanging Christmas lights when the outside temperature is hanging around 97 degrees...

It will be 0C or 32F in Edmonton this weekend! Might even get snow!


It's beginning to look a lot like Christmas!!!

Actually Paul -4C (25F) in Edmonton tonight and it might be a bit cooler where I live. Maybe we will see snow flurries.
It is -2c or 27f at 4 am
Funny thing is it was 32 (over 90f) last year!
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Brad,

Another thing that may help your flicker problem is the addition of a snubber. There are several threads on the forums relating to this topic. I use a single C-9 as a snubber on my LED lights on my roof where I have 15 strings end to end. The fade works correctly up to about 8 strings, then I get the flicker.

The C-9 adds just enough resistance to the circuit to allow for proper dimming. I realize in your case hiding the C-9 might be a challenge. But worth a shot.

Chuck

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Just some technical musings about why an extension cord might cause flicker. Ok so it works just fine when the LED lights are plugged in directly to the LOR dangles, but if an extension cord is added in between, then it flickers during dimming.

I would say that there is some capassitance added between the hot and neutral leads and I am thinking that Dan is thinking about the ground lead, which is a good call also. This capassitance is causing a shift in the phase of the current, thus messing with the Traics ability to shut off cleanly.

But if all else fails I am like mind with Chuck, although a resistor works just as good as a old filiment C9. Might of fact better, cause there is not a light to hide and a resistor rarely fails unlike a burnt out filiment.

Try the C9 first. If that works then get a plug and install the resistor inside and make water proof. Install at the end of the string.

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I had a similar problem 2 years ago with some leaping arches I had made up. They would flicker, hang on, flash... and I had even added a plug inline with a resistor across the contacts.. Now I might not have had enough resistance across the contacts.. the only ones that I had in my bag at the time were some 3.7K 1/4 watt.

I've got a shopping list of stuff to try when I get back to it. Gonna start with Dan's idea about eliminating the ground wire on the ext cords first. But not too sure about that. My leaping arches were run off two conductor zip cord with Vampire plugs on them. Plus the resistors that I had inline.

BUT I appreciate all the input. I'll give all of them a try and let you know..

Thanks..


Edit. Max-Paul, I like your feedback on the phase shift. The lights are acting just like one of my controllers did two years ago when I had half the controller on one phase and the other half on another phase. All the panels that I have power coming from are 3 phase panels. Luckly, on this panel, I only have one circuit running to the controller so everything is on the same phase.

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I agree about the resistive (ghost load) and that will almost certianly work. With some LEDs I have been succesfull at recreating a flicker with extension cords and also eleminating it with the ground removed.

But some LEDs will have issues regardless of extension cords. In those cases a ghost load has always remedied the problem.

Dan

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Dan, I told my boss about how responsive you and your company were. I"m glad to see that nothing has changed. Thank you Sir, and I will take care of it and let you know how it goes when I get back..

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Dan, just pulling your leg.

See some of us who are here answering questions should get paid. But I suppose with demerits (you know what I am talking about). My paycheck keeps coming up $00.00. Well that explains it then why I am not getting a pay check..:(

Sorry just having a little laugh at myself.

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