Home LED Flickers

I love it when people say "full stop" like that makes 'em right. So, you've never seen a thermal intermittent...

Unlikely, maybe. Full Stop, not so much.

A thermal intermittent would not apply to the emitter. It would very much apply to the driver, socket, contacts, whatever. I have seen my fair share, naturally - and none of them were an emitter fault.

Peter Wieck Melrose Park, PA

Surprisingly, the two cheap 60 Watt dimmable LEDs I bought at Walmart, work just fine with the old photo cell socket "night light" adapters. Designed to work with incandescent bulbs, I found out they only take month or two to kill halogen bulbs.

Oh, it happens; I've had multi-LED panels where handling the PC board (not the power brick) caused/stopped the flicker. Not solder, either, some kind of internal-to-the-LED package or thermal fault. Replaced four or five elements, and the lamp works fine now (though my replacement LEDs were a mismatch for the original 'warm' white).

A lot of the cheap Chinese-made LED bulbs for automotive use seem to develop flicker problems. One or more series strings of LEDs start flashing on and off, somewhat randomly, while other strings are unaffected. These don't have a "driver" per se, just a series resistor and (in some cases) a bypass cap.

I haven't been able to tell whether the failure is in one of the individual LEDs in the string, or in the solder bonding of the LED to the substrate. I sorta suspect the latter... bad RoHS-safe-solder junctions, perhaps. The flickering seems to be at least partially a thermal cycling problem... LED comes on, chip heats up, bad junction opens, LED cools down, lather/rinse/repeat.

The time constant is typically a fraction of a second... more of a blink than a flicker.

outside the emitter. Full stop.

apply to the driver, socket, contacts, whatever. I have seen my fair share , naturally - and none of them were an emitter fault.

I've seen plenty of intermittent or even slow to start LED emitter chips. In LCD backlights, I've changed over two thousand of them in the last 5 yea rs.

But, the majority of those were either shorted or open, but the intermitten t ones busted my ass enough to force a change of procedure in bench testing before the display was reassembled. Several thermal cycles as well as und er-volting and over-volting the array will ferret out most intermittents.

n outside the emitter. Full stop.

ch apply to the driver, socket, contacts, whatever. I have seen my fair sha re, naturally - and none of them were an emitter fault.

In LCD backlights, I've changed over two thousand of them in the last 5 y ears.

ent ones busted my ass enough to force a change of procedure in bench testi ng before the display was reassembled. Several thermal cycles as well as u nder-volting and over-volting the array will ferret out most intermittents.

I forgot to add that in no case have I seen an LED chip "flicker", at least not in a steady cadence. OP never clarified what exact kind of flicker he had but I think we've gotten off the subject a bit.

A Practical Example of GaN-LED Failure Cause Analysis by Application of Combined Electron Microscopy Techniques

Page 2: ...after a short time, the blue and white LEDs either started to flicker, showed a reduced light output, or spontaneously failed completely, whereas the red LEDs present in the same module in parallel continued to function correctly.

Page 4: The further observation of cross-sections of the nitride layers inside revealed the reasons for the devices? malfunctions. In Figure 4, an example of a cross-section of an LED exhibiting failure type (B) (flickering dark and bright) is shown. One can see that beside the bond foot, the nitride semiconductor layer has slightly lost contact to the back side of the device and, moreover, shows tiny cracks across the layer.

Sceptre

I have it in my hallway. Standard switch only, no dimmer. Fixture is a common "BOOB LIGHT". (Google that). I haave 3 such fixtures in the house, all have LEDs. Only this one in the hallway flickers. Neither the incan bulb or CFL that used to be in that fixture flickered. So its likely the LED bulb. I bought a bunch of them at Walmart and then Dollar Tree was selling some for ONE DOLLAR (US) for TWO PACK. I stocked up. I am not sure which is in this fixture, but no others flicker from either store.....

So, why don't ya just replace the thing and be done with it?

Am 12.12.2018 um 01:44 schrieb snipped-for-privacy@myshop.com:

If the bulb has an capacitive power supply could be a defective rectifier leeds to flickering.

My thoughts too. I have a celaing fan with 4 bulbs in it. I put LEDs in it a while back replacing the CFLs. I seldom use the fan part, bu the lights stay on from about 9 in the morning to 12 at night almost every day. A few days ago one of the LEDs would go off for about 2 seconds and come on for a short time and off again. I just replaced it. I may open it up just to see one day, but have not taken time to even worry about it. It may have been of the free ones the power company was giving out a few years ago. At one time they gave out about a dozen CFL and then a dozen LEDs a few years later.

One and two dollar or less items are just not worth the time to worry about when they last over 6 months.

I've had bad luck, irregular flicking - with one brand of LED '40w''candelabra' bulbs in which the 'filaments' were plainly visible In the bulb - glass envelope - some filaments flickered while others were fine. Occurred in 4 different bulbs. As I recall each bulb had

Same here. Out of 6 Sylvania candelabra bulbs, 3 did the exact same thing. Replaced with a different brand and no flickering.

This is my opinion. They are made very cheaply they aren't made with much s hielding so anything can cause them to flicker. Now be careful because cans have protection from overheating and it's possible the LED module is not c ompatible with the model of can fixture you have so that's another possibil ity. I would try another unit see how things go.

that simply isn't so. The nature of the circuits makes them robust against RFI.

NT

Hmm. Our Christmas tree has a couple hundred LED lights on it. Am I broadcasting RF to the neighborhood?

Depends on the driver. You would know if you were.

Peter Wieck Melrose Park, PA