Power rating of LED bulb 3

[Fluorescence]

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...

 

[ScottyUK]

Read up on power factor. It is entirely possible for the condition you describe to occur.


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If we learn from our mistakes I'm getting a great education!

 

[itsmoked]

Could easily be they're lying or ignorant too.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[VEBill]

About a week ago, I bought a "7 watt" mains-powered LED light bulb at the Dollar Store.

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."

 

[Fluorescence]

Thankyou all for replying,

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 ?

 

[itsmoked]

For all of these things the first thing you do is buy a Watts Up and just measure the power factor and see the actual watts.

Just use the lowest price one. They are solid quality devices. You can probably find them for less than list too.

https://www.wattsupmeters.com/secure/products.php?pn=0&wai=166&more=5

Keith Cress
kcress -

http://www.flaminsystems.com