22 Feb
2010
22 Feb
'10
10:10 p.m.
On 22 Feb 2010 at 22:35, Alexander Schreiber wrote:
Although by now the LED light output in general is
high enough that
they are used in traffic lights (a lot of the traffic lights around
here (Zurich) use LEDs).
I see them in tailights for buses and trucks also. They have a
somewhat different color (narrower spectral distribution) than
filtered incandescent lamps.
Initially, I mystified my wife by being able to pick out LED
stoplights from several blocks distance. I'm very sensitive (for
some unknown reason) to flicker and those line-powered traffic lights
evidently were pretty high on ripple. More recent ones don't display
that effect, so the power supplies must have improved.
However, to my eye, the biggest abomination are cheap Christmas tree
LED lights with very pronouced flicker. I haven't researched it, but
I suspect that the LEDs in such strings are hooked in series and used
to self-rectify the line current.
I picked up a couple of strings last month at the local "dollar"
store--they're GE-branded. Come Christmas, I run them off of a nice
filtered DC supply--or at least a full-wave bridge.
--Chuck