XPost: uk.d-i-y, alt.home.repair   
   From: Gothberg"@internet.co.is   
      
   On Thu, 20 Dec 2018 20:40:26 -0000, %  wrote:   
      
   > On 2018-12-20 1:30 p.m., William Gothberg wrote:   
   >> On Thu, 20 Dec 2018 19:11:36 -0000, Rod Speed    
   >> wrote:   
   >>   
   >>> "William Gothberg" <"William Gothberg"@internet.co.is> wrote in message   
   >>> news:op.zubnqbkho5piw3@desktop-ga2mpl8.lan...   
   >>>> On Thu, 20 Dec 2018 09:36:02 -0000, Jon Fairbairn   
   >>>>  wrote:   
   >>>>   
   >>>>> "William Gothberg" <"William Gothberg"@internet.co.is> writes:   
   >>>>>> Agreed. All I can detect (with my digital camera) is that   
   >>>>>> one brand of LED light I have flickers about 5 times less   
   >>>>>> (not sure if it's smother or faster) than the others.   
   >>>>>   
   >>>>> Try a longer exposure and move the light rapidly relative to the   
   >>>>> camera.   
   >>>>   
   >>>> I wonder, if I fed the lamps with mains voltage DC, simply a bridge   
   >>>> rectifier and a huge capacitor, they'd reduce their flicker.   
   >>>   
   >>> Wont work at all if they use capacitor droppers and   
   >>   
   >> I made a few of those to power LEDs to indicate the function of my   
   >> central heating.  I'm looking inside the flickery lamp just now (£15,   
   >> 20W).  Without undoing the glue holding the PSU onto the inside of it,   
   >> all I can see is probably: the mains going through a large bipolar cap,   
   >> a tiny resistor (to discharge it safely?), a bridge rectifier, another   
   >> very large resister (to limit the LED current more accurately?), then a   
   >> 400V 4.7uF capacitor (which is bulged).  A capacitor dropper with a   
   >> rectifier and smoothing capacitor after it?  The one I made has no   
   >> smoothing cap, just mains to cap to resistor to bridge to LED.  Perhaps   
   >> this bulged cap is why I'm getting flicker, I'll try replacing it tomorrow.   
   >>   
   >>> they very likely do because those are the only cheap   
   >>> droppers for dropping such a large voltage.   
   >>   
   >> Aren't miniature SMPS units pretty cheap?  I just bought a 12V 6A SMPS   
   >> for £4.50.  Designed for powering LEDs - but I've looked inside it and   
   >> it's definitely a switched mode, not a capacitor dropper.  Now this   
   >> flickery LED lamp I'm looking inside, it's about 20W, so 12V at 2A is   
   >> all that's required, it could have had an SMPS in it similar to the one   
   >> I just described.   
   >>   
   >> I'm now looking inside one of the better LED lamps (the non-flickery   
   >> model).  It has a basic SMPS inside it.  They're 9W and £4 each for the   
   >> whole lamp.  I'm sure it's more than just a standard SMPS though,   
   >> because when some LEDs fail short circuit (it has about 40 in series),   
   >> the voltage coming from the PSU drops, to maintain the correct current   
   >> for the remaining good LEDs.   
   >>   
   >>> Very easy to try tho and see if it works.   
   >>   
   >> Looks like it would help the better ones, but not the crap one.  Better   
   >> (as I only have a few crap ones) to stick a bigger smoothing cap inside   
   >> those.  For the good ones, the only problem I can foresee with the   
   >> external smoother, is overloading the lamp's bridge rectifier, as it   
   >> will only be conducting on two of the four diodes.   
   >>   
   >>>> The cheap shit LED lamp I have that actually flashes at 100Hz would most   
   >>>> likely get much brighter and burn out, so I'd have to adjust that,   
   >>>> but the   
   >>>> others which only flicker 8% would just get 4% brighter.   
   >   
   > you could use being 4 % brighter   
      
   That would make my IQ 140.   
      
   Was the above too difficult for you to discuss?   
      
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