Power rating of LED bulb
Power rating of LED bulb
(OP)
Hello,
I recently purchased a 1 Watt Mains LED light bulb (240V, 50Hz)
Using a 220R resistor in series with the live (hot) line i looked at the current entering the bulb using the scope.
The bulb is said to be 1 Watt but i calculated that the RMS of the input current waveform was 8.75mA...
...this gives a power of 2.1W.
Do you think that they have made a mistake with their power rating of this bulb ?
..here is the current waveform from the mains into the bulb...
[IMG]http://i44.tinypic.com/6h8gtg.jpg[/IMG]
I recently purchased a 1 Watt Mains LED light bulb (240V, 50Hz)
Using a 220R resistor in series with the live (hot) line i looked at the current entering the bulb using the scope.
The bulb is said to be 1 Watt but i calculated that the RMS of the input current waveform was 8.75mA...
...this gives a power of 2.1W.
Do you think that they have made a mistake with their power rating of this bulb ?
..here is the current waveform from the mains into the bulb...
[IMG]http://i44.tinypic.com/6h8gtg.jpg[/IMG]





RE: Power rating of LED bulb
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If we learn from our mistakes I'm getting a great education!
RE: Power rating of LED bulb
Keith Cress
kcress - http://www.flaminsystems.com
RE: Power rating of LED bulb
The bulb isn't really 7 watts. Further inspection reveals four diodes in a bridge and a half-watt (!) series resistor. I'm not surprised in the slightest. New saying: "Lies, d*mn lies, and dollar store packaging."
RE: Power rating of LED bulb
VE1BLL....glad to hear yours only cost a dollar....my "1 Watt" LED bulb cost me £9.33 and took 2 weeks to arrive by post (an extra £3.50 packaging = £12.83 total)
....when i took it apart, i found the electronics was pretty much just a 220nF series cap dropper and a diode bridge, + 4 LEDs....it also had a series 100R resistor.
and i had to smash it to get inside, so its useless now.
Anyway, do you think i will have to first calculate the fundamental of the above current waveform and then get the RMS of that to find the real power consumed ?
RE: Power rating of LED bulb
Just use the lowest price one. They are solid quality devices. You can probably find them for less than list too.
https:/
Keith Cress
kcress - http://www.flaminsystems.com