How to test LED bulb is smoothed or not?

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One light fitting has caused me problems, had to fit load capacitor as would not switch off, and shimmered when on all LED G9 bulbs, wife got 5 replacements which were physically much larger, and one failed after a day, and today I decided to strip the faulty bulb to see how made, but stage one and I could see a capacitor not soldered in, so thought try re-soldering and yes it worked. So not completely stripped.

But I could clearly see a full wave rectifier, and an electrolytic capacitor and I assume a paper one, the latter was one not connected. So it seems reasonable to assume the electrolytic was after the rectifier pity did not take picture.

However it seems reasonable to assume the electrolytic capacitor was reason for no shimmer with these bulbs. Marking did not even show wattage, 220 to 240 volt CE marked and that was it, seem bright for a G9 this G9.jpg design but as large as a E14 candle bulb, could not fit covers.

So my daughter complained about living room lights says it gives her a headache, so wonder it there is a way to test if the bulb has the electrolytic capacitor or not? I can see why the originals had a problem, simply not room to fit an electrolytic capacitor. But is the only way to suck and see, there must be some way to test?
 
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But I could clearly see a full wave rectifier, and an electrolytic capacitor and I assume a paper one, the latter was one not connected. So it seems reasonable to assume the electrolytic was after the rectifier pity did not take picture. ... However it seems reasonable to assume the electrolytic capacitor was reason for no shimmer with these bulbs. .... so wonder it there is a way to test if the bulb has the electrolytic capacitor or not? I can see why the originals had a problem, simply not room to fit an electrolytic capacitor. But is the only way to suck and see, there must be some way to test?
I suppose that depends what you mean by "suck it and see" and "testing" - although there may not be much practical relevance to the difference, since one could not attempt any sort of 'testing' until one had bought one, which one could then 'suck and see'!

So, I'm not sure whether you would calling 'sucking and seeing' or 'testing', but the ones with significant post-rectifier capacitors will generally stay lit for a short period after the AC supply is removed.

Kind Regards, John
 
I have some cheap ones which seam to flicker. I thought the leds were in their way out.

I recommend brand minisun. Seam to be better on the one I have.
 
Try viewing it through your phone camera. If there is flicker which is 'invisible' to the naked eye, you should be able to detect it on the phone screen due the difference between the phone camera screen scan rate and the flicker rate.
 
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It was the minisun I had problems with, among others, but a bulb this G9-small.jpg size simply does not have the room in the package to contain the smoothing capacitor, the one with the capacitor is the size of a E14 candle bulb although cob design.

However the living room lights are E14 and show no sign of flicker to my eye, but daughter complains, there is clearly no point in replacing if already fitted with a smoothing capacitor, so considering method to test, taking photo with DSLR, using small solar panel connected to multi-meter set to frequency, or some thing I have not considered.

Like @Jackrae has suggested, but tried with phone, can't see any sign of banding with lights I know from time to time seem to flicker.
 
So my daughter complained about living room lights says it gives her a headache, so wonder it there is a way to test if the bulb has the electrolytic capacitor or not? I can see why the originals had a problem, simply not room to fit an electrolytic capacitor. But is the only way to suck and see, there must be some way to test?

Speed of decay of light output after switch off. Initial current surge at switch on?
 
Haven't tried, but I wonder what the reading would be if a DVM (set to measure capacitance) was applied to the connections of the lamp? I wonder if the DVM voltage would be high enough to forward bias the bridge rectifier inside and measure the cap...?
 
Since a capacitor is used to limit current, any test would need AC supply, the good bulb does not even state wattage, yes I know that does not comply, should state lumen etc. There was nothing on the box they came in, they simply say 220-240 volt CE and that is the good one.

If I was getting a head ache, then easy, no head ache, good bulb, but daughter who visits for short time, how do I work out which lights I can use when she is here, I have used tungsten standard lamps up to now, but as tungsten bulbs blow, they are replaced with LED, so getting to the point were not many tungsten lamps left.

So want to be able to select good lamps to use when she visits.
 
Haven't tried, but I wonder what the reading would be if a DVM (set to measure capacitance) was applied to the connections of the lamp? I wonder if the DVM voltage would be high enough to forward bias the bridge rectifier inside and measure the cap...?
There will be a (relatively 'low' value) series capacitor in the AC input 'in the way', so that wouldn't really be useful (even if it worked at all).

As I and others have said, the 'speed of decay' of light after switch-off should be a pretty good guide. With no (or no significant) post-rectifier capacitor the light will go away immediately, but with a significant post-rectifier capacitor it will persist for a while.

Kind Regards, John
Edit: Just noticed eric's latest reply, which I hadn't previously seen!
 
If I was getting a head ache, then easy, no head ache, good bulb, but daughter who visits for short time, how do I work out which lights I can use when she is here ... So want to be able to select good lamps to use when she visits.
I think one of the problems is that of quantification.

You could presumably 'properly test' the situation by using some sort of light-sensing element (without 'persistence') and looking at its output on a 'scope' to determine the magnitude of the 50 Hz component in the light output. However, with any credible smoothing capacitor (given the space constraints), there will inevitably be some degree of 50 Hz flicker in the light output, so you would presumably need to know (or ascertain) what degree of 50 Hz variation in the light was enough to cause problems for your daughter.

Kind Regards, John
 

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