MR16 LED COB bulbs

[robgraham]

I bought a set of 4 off 12v MR16 COB bulbs - in the end they cost me nothin g as I ordered warm bulbs and was sent cold ones so got a refund.

After 6 months one failed and a couple of months later a second in a simila r manner of flashing and then dead.

I've now found that the base housing just screws off giving access to a bit more complex a bit of electronics than I expected - a 15mm square pcb with what might well be a switching regulator under a layer of white silicone.

Has any one explored one of these a bit further ?

I've tended to discourage the use of mains powered leds as the voltage drop must put a fair stress on any electronics but I didn't expect to find this on 12v ones.

The incandescant bulb was so simple - maybe that is why the design was so l ong lasting. The basic LED is long lasting too on the same principle, but i t is not going to work as an acceptable light source if like the compact fl uorescents it has to have electronics to drive it.

Rob

[Brian Gaff]

Bit of a sweeping statement there. Surely many basic switch mode power supplies run for many years if the components are of good quality. Brian

[Adrian Brentnall]

I think that's the key to it Brian, the 'design down to a cost' philosophy.

I look after the lighting in our little co-op shop - something in the region of 60 LED GU10 spotlights (yes - I know it's the wrong way to go!

- but it's all we could afford at the time). We've been bulk-buying the 'ebay cheapie' GU10 LEDs, and I have two large boxes of failed bulbs in the workshop - waiting for a round tuit..

Need to establish whether it's the leds themselves (four or five of them in each 'bulb') or whether it's the little switching regulator. Just need a spare hour or two to have an investigate! Maybe over Christmas ?

We've just taken the plunge and bought some more expensive GU10's from lightrabbit.co.uk - I relamped the back of the shop and the difference is noticeable - we'll have to see whether they are more reliable than the cheapie ones - but the uk ones come with a 4 year guarantee, so that's encouraging...

[snot]

Ultimately it's the design and manufacturing quality of the drive electronics that is vital to the long life and efficiency LED lamps. The chip is in effect a complete switching regulator optimised to drive the particular LED's used in the lamp. See here for more info

A bit of Googling finds lots of info about LED driver chips. Dave

[Grimly Curmudgeon]

My lightrabbit ones are still working fine and give me no cause for concern regarding lifespan, with the guarantee that came with them. However, my most recent foray onto lightrabbit's site had me leaving it in disgust and giving my business to LED Hut instead. Lightrabbit were in the habit of giving free postage, and so it seemed this time around too, but at the checkout they charged me. Turns out they've made it free over ?35/£35 now and neglect to make this plain on the front page, the little fact of that being hidden in a sneaky asterisked way. LEDHut, otoh, have always charged me, and I had no illusion that they'd do otherwise. Ironically, LEDHut's postage charge was lower than L-R's anyway, so guess who'll be getting more of my business.