XPost: uk.rec.driving   
   From: no@spam.com   
      
   On Sat, 27 Apr 2013 21:43:25 +0100, Ian Field    
   wrote:   
      
   >   
   >   
   > "Major Scott"  wrote in message   
   > news:op.wv199bfr2eh2io@red.lan...   
   >> On Wed, 24 Apr 2013 11:06:50 +0100, Ian Jackson   
   >>  wrote:   
   >>   
   >>> In message   
   >>> <2082196069388490010.841939%steve%-malloc.co.uk@news.eternal-september.or   
   >>> g>, Steve Firth <%steve%@malloc.co.uk> writes   
   >>>> Dave Plowman  wrote:   
   >>>>> In article ,   
   >>>>>    Major Scott  wrote:   
      
   >>>>>   
      
   >>>>>   
   >>>>> No idea. They are crap and I wouldn't have one in the house.   
   >>>>   
   >>>> The LED bulbs I have used have been anything but "crap". They use 1/10th   
   >>>> the electricity of equivalent halogen bulbs and can be bought as flood   
   >>>> or   
   >>>> spotlight versions.   
   >>>>   
   >>> I was under the impression that they did use a pulsed supply in domestic   
   >>> lighting.   
   >>   
   >> If they do then it's a much higher frequency.  Some old cheap ones I've   
   >> got have a definite flicker, but that's mains flicker (I looked inside one   
   >> I accidentally dropped from the loft through the hatch onto wood flooring   
   >> and smashed it and found simply a bridge rectifier, a capacitor, and a   
   >> couple of resistors, with 50 tiny LEDs in series).   
   >>   
   >> The decent CREE ones I've got have zero flicker.  Here's one that expired   
   >> and I opened to show Ian Field the circuit a month or three ago if you   
   >> want to try to work out what it does:   
   >> http://petersphotos.com/temp/cree%20circuit.jpg  I don't have it anymore   
   >> it's gone in the bin.   
   >   
   > There doesn't look enough components for it to be a half bridge, a flyback   
   > is most likely.   
   >   
   > Switching frequency is probably somewhere between 20kHz & 50kHz.   
      
   Somebody oughta tell BMW.   
      
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