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THD In Light Bulbs

I have replaced a 40w incandescent light bulb with a 12w LED light bulb. The new LED is way brighter. In fact, the box says that it's a 75w equivalent. The box also shows something interesting:

Power Factor >.90  
THD: <35%

I've read that LEDs are essentially diodes. How does this affect noise in the mains? Do LEDs inject more, less, or the same amount of THD into the mains as incandescent/fluorescent lights? 
c_avila1
tablejockey
3,768 posts
 
LED=light emitting diode
Are you hearing more noise with it on? If not, just enjoy your music.
Best to turn off, unplug  EVERYTHING in your house for true sonic enjoyment.

That's if you follow the "keep the power pure" philosophy.

millercarbon's avatar
millercarbon
12,531 posts
 
Yeah, I noticed that too. LEDs are not essentially diodes. LEDs are actually diodes. 

But hey don't take my word for it. Try reversing direction, see how that goes.
audiozenology
362 posts
 
If you are not using a dimmer, then I would not get too worried. It's just another small switching power supply on your AC line, and odds are you already have quite a few (all those USB chargers, and they can be worse).

If you have a dimmer, then yes, things could be noisier as the power supply in the bulb will have capacitors on the front end which will result in higher peak currents when the dimmer turns on (120 times a second, 100 in some parts of the world).

There are some bulbs/lights that do not have switch mode power supplies in them, but simple linear regulators. They are common in low cost flush mount ceiling lights, but not very common in bulbs. I would avoid most as they can have lots of invisible flicker.
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