Does 120 VAC LED light bulb have a built in rectifier?

Question

LED light bulb works on forwar bias and off on reverse bias. Are we simply let the negative part of the AC current go wasted (as it can not light up the bulb) or we rectify it (the negative AC) to continue lighting up the bulb? If the negative part of the current is not use, will the LED light bulb flicker like the florescent light?

Answer 1

To start off, just because it allows current one way does not mean it is a true rec. A rec is a series of four diodes, and leD is one by definition and therefore cannot be a rectifier.

To actually answer your question, AC current varys at a rate of 60Hz in the United States, so even if you did not rectify the currect you would not see flickering (TVs changes full pictures at a rate of 30Hz). Instead, the lightbulb would appear half as bright. This is actually how many display boards control brightness, plusing the lights on and off very very quickly at different rates (the faster the brighter).

For a lightbulb, however, especially when dealing with LEDs, one wants want max brightness (LEDs are generally not very bright). I assume, therefore, that commercial LED bulbs have built in recs as to maximize brightness.

Answer 2

Yes by definition a single diode is a rectifier regardless if it is a regular diode or an LED-- they are HALF wave rectifiers. This would mean the negative cycle is not used. Technically it is not wasted because no current flows to create power, which consumes energy. On a 60Hz circuit, it turns on and off too quick to see it; did you know fluorsecent lights are doing the same thing? Take a high speed photograph of one and tell me what you see! :^)

You would need 2 or 4 LEDs to use the whole AC cycle because that would make a full wave rectifier. In the first setup, one led would light while the other is off and vice versa; on the 2nd setup, you'd make a bridge rectifer where 2 of the arms of the bridge would light and the other two would be off and vice versa.

However again, on a 60Hz circuit, you'd see all of the LEDs burning on all 3 of these arrangements!

Answer 3

Led Rectifier

Answer 4

White LED bulbs 120 vac


LED's last 10 times longer than compact fluorescents and 133 times longer than a typical incandescent. And energy savings are incredible. It would cost $772.20 to use one hundred 25 watt incandescents for 13 hours a day for one year compared to only $30.80 using these light-equivalent LEDs - a savings of $741.40. They only produce 3.4 BTUs/hr. compared to 85 for incandescents - no more heat problems. And they fit in standard recepticles, lamps, recessed cans, track lights, any place you would use a normal bulb. The 17 LED version replaces a 25 watt incandescent and uses only 1.7 watts. 9 LEDs in a n A-19 bulb - the same style as a typical incandescent (2 3/8 diameter). They look the same, have the same base, and replace a 25 watt incandescent while using less than .9 watts.

Answer 5

An LED is a rectifier. It turns on when voltage is applied in the forward direction and off when in the reverse direction. To operated on 120 VAC it would have to have a current limiting resistor in it.

Answer 6

All LED's are diodes(light emiting diodes) so they are rectifiers(half wave) you just can't see 60 cycles (movies flicker at 30ish )

Answer 7

L = light
E = emitting
D= diode = rectifier - current flows in one direction
- it should not flicker

Answer 8

i imagine Sri Vidya Rajgopalan has given the excellent answer. even if the answer is very lengthy. enable me clarify you briefly. Ram equipped a Bridge rather of deliver because he idea, if contained in the conflict with Ravana extra military of Varana is needed then it's going to be consumer-friendly to carry reinforcement through a Bridge Than to deliver deliver.

Answer 9

Yes