Home Guy wrote in :

Andy wrote:

I recently bought some blue LED nite lights from our local
Dollar Store ( for $1 USD each )

They are advertised to draw only 0.4 watts ...

Your typical high-brightness white LED can be powered to full brightness
by applying about 3.0 volts and maybe 25 milli-amps max. That works out
to 0.075 watts. You can buy high-brightness white LED's from Digikey
for anywhere from 10 to 25 cents each.

I don't know why or how your blue LED would draw 400 milliwatts. That's
crazy, unless there are 4 or 5 LED's in each unit.


no,whatever is dropping the **170V** peak-rectified line V to 3.5V is
what's consuming the extra power.You have to consider the TOTAL V-drops for
power consumed.

170 x .025 = 4.25W.

You should just go with the cheap white LED's. They give off a more
natural light vs those blue ones.


A "white" LED is just a blue LED with phosphors on top of the die,the blue
LED(also emits UV) energizes the phosphors to give off a "white" light.
that's why they appear yellow when off. That's the phosphors you see.

that's why both blue and "white" LEDs have the same V-drop;around 3.5V.

--
Jim Yanik
jyanik
at
localnet
dot com