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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 22nd Apr 2018, 5:53 pm   #1
ex 2 Base
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Default LED lighting

My son bought some LED strip lights for his workshop, thinking they would last a 'life time' only to find several failed within a few months. After searching around he now says some LED (cheaper one) are made to a lower standard than others and those are the ones which fail. Could that be possible ? Having used lots of rectifying diodes in the past with few if any rejects I find that incredible. Could manufactures used inferior material I thought the cost was in the making not the material. John
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Old 22nd Apr 2018, 6:25 pm   #2
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Default Re: LED lighting

When any technology is being perfected, there are bound to be early failures.

Someone probably figured if they were going to end up in a landfill site anyway, it might as well be a landfill site near some gullible punter who expected them to last a lot longer, even at that price .....
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Old 22nd Apr 2018, 7:24 pm   #3
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Default Re: LED lighting

It's not usually the LEDs which go. There's also a switch-mode regulator driving them, and if a switcher is made out of the cheapest components....

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Old 22nd Apr 2018, 8:43 pm   #4
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Default Re: LED lighting

A couple of years ago I got a pair of LED camping lanterns from a local Maplin shop (5 LEDs per lantern), and the individual LEDs (all connected in parallel) started failing after less than an hour (the first in under 5 mins!). I took them back for replacement (no problem, less than a week old) but the replacements behaved the same. They then had a pair sent to me by mail, and they were fine: still going strong and much brighter initially. I guess the LEDs in my first ones must have been from a dodgy batch.
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Old 22nd Apr 2018, 11:49 pm   #5
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Default Re: LED lighting

I was an enthusiast for LED lighting and started replacing everything- but have found it a pain in the neck ever since, most things have totally failed or at least gone loopy that includes torches, downlighters/gls replacements,car replacement bulbs.
The kitchen downlights resembled a flaming disco one day.

The only things that are holding up is an old Wickes single LED torch and the Christmas lights.
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Old 23rd Apr 2018, 7:31 am   #6
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Default Re: LED lighting

My experience is quite different to cheerfulcharlie's

I had a few early failures but that was when LED's were very expensive and I bought them cheaply on line but that was more than 8 years ago.

But even those if you could get them apart were repairable.

In the last 5 years even the Poundland LED's have lasted well.

The most consistent cheap LED's are the dimmable ones I buy from IKEA.

IKEA do a cheap adaptor for BC (2 for £1) most but not all are ES

At work we supply thousands of LED optics monthly some have now been in use for more than 10 years the failure rare is tiny. We occasionally get manufacturing problems that results in premature failure of the end of life fuse.

This fuse should only blow when the driver is unable to push enough current into the LED plate to maintain light output due to LED failures on the cross coupled string of LED's. (4 or 8 LED's on most optics).

As these are industrial we massively under run the individual LED's since on a hot day in direct sunlight the plate temperature can be 100C plus.

We are almost 100% LED at home now

Cheers

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Old 23rd Apr 2018, 10:07 am   #7
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Default Re: LED lighting

A lot of the cheaper LED lighting drives the LEDs really hard to get maximum light-output (for marketing reasons) at the expense of reliability. Some I've seen use series-parallel chains of LEDs [six series-connected strings each of six LEDs for example] - problem then is that when one single LED dies it either goes O/C and you lose 1/6 of the light output, or it goes S/C and increases the voltage on the other LEDs in its series-string, so they get driven even harder and a 'chain of failure' ensues.

Some of the multiple-series-string LEDs don't bother to use current-sharing resistors either - so it's easy for one series-string to be working a lot harder than the others!
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Old 23rd Apr 2018, 10:26 am   #8
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Default Re: LED lighting

My experience of LED lighting has also been good. For some years I had three 7W CFL's in the living room and dining room fittings. These used to last a couple of years and I then found it difficult to find the 7W types. By chance B&Q were selling a box of five LED types of the correct fitting and equivalent light output at a special price. I bought two boxes thinking they would probably be unreliable.

Well I was wrong! I fitted three new ones to the original light fitting and they have been there ever since (getting on for five years now). I was so impressed by them I now have the same fitting in the dining room with three LED's. No problems with either and I have four spare LED lamps should I ever need them. So far both sets have outlasted the previous CFL's. The LED's are rated at 3W so there is a further power saving for each fitting.....9W total instead of 21W. Light output seems to be the same as the old CFL's and of course there is none of the annoying 'warm-up' time.

When we did the kitchen a couple of years ago, the wife wanted spotlights (yuk) and chose a particular fitting that came with three Halogen spots at 50W each! I decided to seek out LED equivalents which I found easily....5W each with the same light output. It was no contest! The fitting has been in place for nearly three years with the three 5W spots fitted...no problems and only 15W total instead of 150W and of course much less heat.

Gradually I will be replacing all the lights with LED's when the CFL's fail.

I see a very bright (pun intended) future for LED lighting!
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Old 23rd Apr 2018, 11:42 am   #9
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Default Re: LED lighting

Over the past year or so, I've switched 14X 240V 50W halogens to 5W LEDs with no problems at all, and if anything a more pleasant, warm white, light. All of the 5W LEDs came with 5 yrs warranty - if it's worth the paper it's written on....

I'd still like to change a 4X MR16 spotlight fitting from 20W halogens, to LEDs - I did try a few MR16 LEDs a few years back, but none lasted longer than a few months, so I reverted to halogen, and got 20X Philips 20W MR16, at a very good clearance price.

Question - is it now worth trying again, with some of the newer LEDs ? I keep reading that the MR16 sizes esp. are more problematic in older fittings, but wondered if the spotlight I'm considering is now so old, that it's good again ?!...... the spotlight fitting is an older twin cable type, operating on 12V AC from a conventional toroidal transformer. No dimming fitted or needed.

Alan
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Old 23rd Apr 2018, 10:44 pm   #10
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Default Re: LED lighting

It may be of interest to know that having condemned an ES 'dimmable' 240v lamp that had expired but was still taking pulses of current, i decided to open it up.

This was like attacking a Tiger with a Sherman, and it soon became apparent why- Osram were (or are) so nervous about reverse-engineering that the whole lot had been potted!

I have retained the bits out of sheer muddy blindedness, but several chips and capacitors ended up getting mutilated as i broke my way in.

Osram beware, the method i adopted isn't quite capable of breaking in without damage, but you have not reckoned with Big Clive!

Dave
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Old 23rd Apr 2018, 11:08 pm   #11
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Default Re: LED lighting

Potting costs money (quite a lot of money) if it's potted it's not to stop reverse engineering that will happen anyway it's for reliability stability or some other reason.

Cheers

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Old 24th Apr 2018, 7:15 am   #12
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Default Re: LED lighting

Quote:
Originally Posted by Goldie99 View Post
I'd still like to change a 4X MR16 spotlight fitting from 20W halogens, to LEDs - I did try a few MR16 LEDs a few years back, but none lasted longer than a few months, so I reverted to halogen, and got 20X Philips 20W MR16, at a very good clearance price.

Question - is it now worth trying again, with some of the newer LEDs ? I keep reading that the MR16 sizes esp. are more problematic in older fittings, but wondered if the spotlight I'm considering is now so old, that it's good again ?!...... the spotlight fitting is an older twin cable type, operating on 12V AC from a conventional toroidal transformer. No dimming fitted or needed.
I put 9x 20W halogen downlighters in my kitchen 18 years ago. Not wanting SMPS running and causing havoc with HF reception, I chose kits with 3 lights on a single iron transformer.

I didn't like the temperature the transformers reached, so I went to one transformer per light. So that made the inrush trip the 6 Amp MCB. Damn! so they were wired in three groups of three, with DIN rail sequencing timers set to 1 second in an added box. The neighbours were amazed at lights turning on in sequence!

Two years ago I fitted Osram LED replacements for the halogen bulbs. They've been fine. I could now rewire it all and cut the number of transformers and remove the timers, but it's still rather cute!

David
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Old 24th Apr 2018, 9:12 am   #13
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Default Re: LED lighting

That's what I thought Mike, but I couldn't find anything that appeared to need potting..Moreover when switched on it was getting uncomfortably hot, which seemed to be due to the heatsink not being able to dissipate to air. Photos later. There is a little black spot in all four LED's so I suspect they have failed. Overdriven?
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Old 24th Apr 2018, 9:45 am   #14
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Default Re: LED lighting

Cheers David - sounds like it's time to try again.
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Old 24th Apr 2018, 10:37 am   #15
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Default Re: LED lighting

The failed LEDs in my camping lantern developed spots that got progressively darker as they got dimmer and dimmer over a few minutes until they failed completely.
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Old 24th Apr 2018, 10:58 am   #16
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Default Re: LED lighting

The LED Christmas lights are lasting well, even the thre sets I put up outside. I have had one LED failure on one cheap torch but apart from that everything looks good with all 19 LED's on my first LED torch, bought 12-13 years ago, still working well.

I have not replaced any of the Halogen or incandescent bulbs around the house with LED upgrades because of the terrible radio interference that their cheap and nasty switch mode power supplies generate which makes my radio dxing hobby impossible. I have tried contacting the technical departments of the major LED bulb makers but no one can or will provide me with any information on the type of drivers that they use in their LED bulbs. I am after an LED bulb that uses a capacitive mains dropper rather than a switch mode PSU/dropper.
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Old 24th Apr 2018, 12:41 pm   #17
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Default Re: LED lighting

I have been considering converting the lighting circuit to low voltage with a single transformer. I have a big heavy 24 volt lump of iron that is not allocated to anything that would do.
With LEDs in strings and with a FET and 100K pot in each switch they would be fully dimable with no RF noise.
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Old 25th Apr 2018, 8:56 am   #18
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Default Re: LED lighting

I found a capacitive mains dropper feeding the LEDs in a kettle.
Why a kettle needs to light up inside is something else.
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Old 25th Apr 2018, 10:40 am   #19
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Default Re: LED lighting

I replaced the tube in my elderly aunt's old circular fluorescent light about seven years ago. As you would expect she has the light on several hours a day, the tube a German Sylvannia,cost about 9 quid, gives out a rich penetrating daylight white for her reading and fiddly tasks.. and still has no dark patches around the ends. At the time I was contemplating converting her to LEDs but glad I didn't as I probably would have been up there several times a week.
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Old 25th Apr 2018, 11:32 pm   #20
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Default Re: LED lighting

I bought two types of 4W 'candle' LED bulbs recently for someone's wall lights.

The standard opaque bulb probably had a switched mode power supply inside and it got hot after 20 minutes of use.

However the type with the new visible LED 'filaments' in a clear glass bulb was a lot cooler.
I was impressed by its performance even though I would have preferred an opaque glass envelope.

The packaging says it has an A++ energy rating.

Research online suggests that these 'filament' type of LED bulbs use a capacitive dropper and rectifier power supply.
I have just tested it near an FM and an AM radio and there is no interference.
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