Ruby60 Posted December 15, 2012 Share Posted December 15, 2012 Can someone please explain flicker to me...I don't understand why it happens.I attached 4 strands of LEDs together with no discernable (at least to me) flicker. I then added 1 more strand to the string and wow.... it looked like shimmering...clearly a flicker issue.I know about snubbers to add a resitive load, but isn't the load of 5 strings greater than the load of 4 strings?David Link to comment Share on other sites More sharing options...
scubado Posted December 15, 2012 Share Posted December 15, 2012 Try adding a snubber or a string of incads for a test. You're picturing in your head that leds are similar to incads but they are a whole different animal to tame. Link to comment Share on other sites More sharing options...
WilliamS Posted December 15, 2012 Share Posted December 15, 2012 Theres many variables to LEDs, not only do amount to create a load come into play, but some have resistors or packs on them to help with the flikering. Some are full wave, some are half. Try a snubber to see if it helps or as Jim stated add some incans. Link to comment Share on other sites More sharing options...
Ruby60 Posted December 16, 2012 Author Share Posted December 16, 2012 So is it the rapid charge and discharge of these capacitors making the LEDs flicker? Link to comment Share on other sites More sharing options...
-klb- Posted December 16, 2012 Share Posted December 16, 2012 Can someone please explain flicker to me...I don't understand why it happens.I attached 4 strands of LEDs together with no discernable (at least to me) flicker. I then added 1 more strand to the string and wow.... it looked like shimmering...clearly a flicker issue.I know about snubbers to add a resitive load, but isn't the load of 5 strings greater than the load of 4 strings?DavidThe thing is that the LEDs are not a linear load. Below the sum of the junction voltages, they conduct about zero current, and the capacitance in the wiring becomes significant in the behavior. Adding more strings adds more capacitance, more than it adds load below about 90VDC, as nearly all the current drawn by LED strings happens when the wave form is above 90VDC. The controllers need something to discharge that voltage back down to zero smoothly. Adding resistive load provides a path to drain that capacitance stored voltage. Link to comment Share on other sites More sharing options...
Max-Paul Posted December 16, 2012 Share Posted December 16, 2012 Ya, what klb said.Thanks klb for saying what I wanted to say in a more precise manner. Link to comment Share on other sites More sharing options...
Ruby60 Posted December 16, 2012 Author Share Posted December 16, 2012 -klb- Thanks for the explaination. Not to be disrespectful to the other responders, but you seem to be the only one to have read my original post. "Can someone explain flicker to me.....". I was curious as to what CAUSES flicker, not about using snubbers to solve the problem.I have read the "snubber" posts ad nausem, and made snubbers for use in my display. As for the forum snubber thread, I'll look at it once again, but off hand I don't recall reading why flicker occurs... just reading and looking at O scope tracings and how snubbers affect the wave form. ( but my memory isn't what it used to be...)David Link to comment Share on other sites More sharing options...
EARLE W. TALLEY Posted December 16, 2012 Share Posted December 16, 2012 There are a number of reasons for flicker as noted above and how to fix them, also as noted above. I found another reason, that I just fixed this morning. Last night channel 16 on my mini trees had a "flicker", the lights are from good vendors and are the same on all the mini trees and all has a snubber. I went out this morning to replace the controller, thinking I had a bad channel, Then I found the problem, the plug for channel 16 was not in all the way. Pushed in the plug, tested, no more flicker. Always check for the simple things first. Earle Link to comment Share on other sites More sharing options...
shfr26 Posted December 16, 2012 Share Posted December 16, 2012 I have another question, I posted here earlier today and it is now gone. Can the person that is deleting my post at least have the courtesy to P.M. me and tell me why??? It was a funny, why delete it?? This really is uncalled for by who ever the "adim" is that is doing this. If you have a bone to pick with me, email, P.M. or call me!! 1 Link to comment Share on other sites More sharing options...
shfr26 Posted December 17, 2012 Share Posted December 17, 2012 I have another question, I posted here earlier today and it is now gone. Can the person that is deleting my post at least have the courtesy to P.M. me and tell me why??? It was a funny, why delete it?? This really is uncalled for by who ever the "adim" is that is doing this. If you have a bone to pick with me, email, P.M. or call me!!So I guess this means that whoever removed my post is not going to answer. I make a little joke that could not be taken wrong by anyone to add some humor, and a "admin" removes it. What is it with "admin" that make them remove posts that are not harmful at all?? Is it a power trip or something?? I thought humor was allowed as long as it was not offensive to anyone??? Link to comment Share on other sites More sharing options...
viennaxmas Posted December 17, 2012 Share Posted December 17, 2012 Ruby -A lot of people pointed out that there are different kinds of flickering. There is a "slow" flickering and a "fast". The slower type is mostly caused by the circuitry of the dimmer not supporting very low loads. They just need a certain current to operate correctly. Thee can also be incompatibilities between the dimmer circuit and a circuit being part of the LED which then creates an oscillating system.One of the most common reasons for flickering is the lack of a rectifier. LED's in general are DC devices and current can only flow in one direction. When using AC without a rectifier, the LED can only use one of the two half waves to produce light. The other half wave does get omitted. This would mean: the LED turns on and off and the LED only produces light half of the time. A rectifier helps by folding the lower half wave up, this doubles the "On" time. Since it is still a sinus wave, the LED still turns on and off, however there are no 50% dark periods.So to smoother out the power, a capacitor can be used which hold a bit of energy until the next wave hits...Hope this is not more confusing... 1 Link to comment Share on other sites More sharing options...
Ruby60 Posted December 18, 2012 Author Share Posted December 18, 2012 viennaxmas- ah ha!! .. makes perfect sense and I think I understand it now. Thanks for the explanation! Link to comment Share on other sites More sharing options...
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