My kitchen fluorescent lamp which is 6 foot 100 watt unit wouldn't light tonite the starter flickered but no sign of any tube activity. It was very cold in the kitchen so I put the boiler on which warmed things up nicely I tried the tube again and although a bit sluggish it lit ( maybe my swearing at it helped) my question is do you think it's just because the tubes old and doesn't like the cold or is there something else going on?
I have occasionally noticed flicker from LEDs - not directly but by fast movement being made to look jerky (stroboscopic effect) - in my case when sharpening a knife on a carborundum stone. I guess that's the same effect as from the old fluorescents they were always warning us about (and the need to feed workshop lighting from all three phases etc) although the frequencies might differ. As far as I can gather some white LEDs work on a similar principle to fluorescents - i.e. UV rather than visible light is initially produced and that's used to make phosphor glow to produce visible white light. So in principle flicker from an LED shouldn't be any worse than from and old switch-start fluorescent - probably somewhat less noticeable as the basic LED frequency is likely to be higher than than the fluorescent's 50Hz - notwithstanding slight differences in the phosphor mix.
- Andy.
If I may add a personal observation or two.
I have noticed that LED lamps designed to be dimmable tend to have a flicker (which becomes more pronounced as you dim them) whereas non-dimmable types do not. I presume this is because they are designed so that the thyristor dimmer can chop the output waveform whereas non-dimmable types rectify the mains input - or something like that - does anyone have any intimate knowledge of this?
Don't kid yourselves that tungsten filament lamps are totally flicker free; they are not. Remember those "strobo-disks" you could once get to check the speed of gramophone turntables? They worked quite well under tungsten light.
I have occasionally noticed flicker from LEDs - not directly but by fast movement being made to look jerky (stroboscopic effect) - in my case when sharpening a knife on a carborundum stone. I guess that's the same effect as from the old fluorescents they were always warning us about (and the need to feed workshop lighting from all three phases etc) although the frequencies might differ. As far as I can gather some white LEDs work on a similar principle to fluorescents - i.e. UV rather than visible light is initially produced and that's used to make phosphor glow to produce visible white light. So in principle flicker from an LED shouldn't be any worse than from and old switch-start fluorescent - probably somewhat less noticeable as the basic LED frequency is likely to be higher than than the fluorescent's 50Hz - notwithstanding slight differences in the phosphor mix.
- Andy.
If I may add a personal observation or two.
I have noticed that LED lamps designed to be dimmable tend to have a flicker (which becomes more pronounced as you dim them) whereas non-dimmable types do not. I presume this is because they are designed so that the thyristor dimmer can chop the output waveform whereas non-dimmable types rectify the mains input - or something like that - does anyone have any intimate knowledge of this?
Don't kid yourselves that tungsten filament lamps are totally flicker free; they are not. Remember those "strobo-disks" you could once get to check the speed of gramophone turntables? They worked quite well under tungsten light.
