Curious bulb behaviour
On 06/05/2020 21:24, ARW wrote:
On 06/05/2020 20:50, Tim+ wrote:
A LED pendant light with a supermarket own brand 9W bulb is running
considerably dimmer than normal.* Additionally when switched off it
fades
our over a second or so (which it never used to do).
Has anyone else seen LED bulbs behave like this?* New to me.
Yes.
Seen all sorts of **** with them. But that is one I have seen.
Most likely one of the LEDs in the chain has gone high impedance or that
there is a resistive dry joint in it. The LEDs all glow dimmer on lower
current and the time constant to discharge the PSU capacitor is longer.
The other one I see fairly often on the cheapest and nastiest is a
single LED failure in a long chain taking the entire thing out
completely. Better ones have two or three LED chains so that you don't
lose everything if one solitary LED turns up its toes.
There is a technical term for it....
Modern LEDs are so efficient that they sometimes glow when "off" just
from the capacitive leakage current from the mains wiring.
--
Regards,
Martin Brown
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