Ac Led?

[Muhammad89]

Hi dukes,

In a so nut shell! is there an AC LED, and what voltages range can it be up to fed?


Muhammad89

 

[3v0]

A LED is a Light Emitting Diode. Diodes only allow current to flow one way. So the answer is no. But you could rectify the current first or use a bicolor which is one color when the voltage is + and another when it is -, you would see a mix of the two colors.

 

[Muhammad89]

A LED is a Light Emitting Diode. Diodes only allow current to flow one way. So the answer is no. But you could rectify the current first or use a bicolor which is one color when the voltage is + and another when it is -, you would see a mix of the two colors.

[Diodes only allow current to flow one way. So the answer is no], a typical Diode can be fed with AC and the result as you pointed out, a halfwave in whichever side of the wave,+ or -,however,if they are both diodes,so a LED will also light up when it is fed with AC unless that the light is expected to be alternatively not continuously.Am I worng?


Muhammad

 

[Muhammad89]

[Diodes only allow current to flow one way. So the answer is no], a typical Diode can be fed with AC and the result as you pointed out, a halfwave in whichever side of the wave,+ or -,however,if they are both diodes,so a LED will also light up when it is fed with AC unless that the light is expected to be alternatively not continuously.Am I worng?


Muhammad

I think I have repeated the question!
I now grasp it, so thank you ?


Muhammad89

 

[Hero999]

You can get bipolar LEDs for AC operation - just connect a resistor in series and they work.
**broken link removed**

 

[audioguru]

The max allowed reverse voltage for a rectifier diode could be hundreds of volts or thousands of volts.
But the max allowed reverse voltage for most LEDs is only 5V. That is the peak allowed voltage. The max allowed RMS voltage is only 3.5VAC.

An LED flickers at the mains frequency when it is driven with rectified AC. Since it is turned off for half the time it appears dimmed.

 

[crutschow]

A LED is a Light Emitting Diode. Diodes only allow current to flow one way. So the answer is no. But you could rectify the current first or use a bicolor which is one color when the voltage is + and another when it is -, you would see a mix of the two colors.

You could also use two diodes of the same color in parallel, one + - and the other - +. They would alternate lighting on each half of the sinewave. Of course the light output is only equal to one diode operating on rectified AC or DC at the same average current.

 

[Hero999]

An LED flickers at the mains frequency when it is driven with rectified AC. Since it is turned off for half the time it appears dimmed.

True but less noticable if you use a bipolar LED or a bridge rectifier rather than a half wave rectifier.

 

[audioguru]

My LED Christmas tree lights have a noticeable flicker. My mains is 60Hz. It would be more noticeable at 50Hz.

Have you noticed car LED tail lights pulsing at night when they or your eyes move?

 

[Mark Main]

Below is a link that looked nice, but I've not tried it yet; however, read the next link below because you may want to modify what's in this first link:

https://www.turbokeu.com/myprojects/acled.htm

Like I said, look at this link too, especially at what Roff said, because he avoids connecting the diode directly between the lines for safety and power consumption reasons:

https://www.electro-tech-online.com/threads/how-to-drive-led-from-ac240v.16808/#post98018