The yellowish green indicator LED in my electronic bug deter flickering « on: September 01, 2010, 09:55:03 AM » Author: dor123
http://www.youtube.com/watch?v=vWrPZxHiDU4 The flickering is because the LED recives a pulsed DC and this is common with LEDs in electronic and electromechanic appliances. Flickering of LEDs with the mains frequency is abnormal and usually related to a problem with the current limiting equipment of the LEDs, since LEDs are low voltage, DC devices. The same is with fluorescents operated on electronic ballasts.
« Last Edit: May 03, 2011, 05:24:40 AM by dor123 »		Logged

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Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.

	Re: The yellowish green indicator LED in my electronic bug deter flickering « Reply #1 on: September 01, 2010, 05:27:31 PM » Author: Medved
LED's are indeed low voltage DC devices, but they are tolerant, if the "DC" is not filtered, or even pulsing, if the resulting pulsing light is of no problem. So when it is required to supply the LED from an AC, there is no filtering necessary in it's supply circuit for most applications, so it is omitted. The result is then a LED flashing with the mains, or double of the mains frequency (e.g. an indicator LED is fed from AC by simple series diode and resistor - then it flickers at 50Hz).
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	Re: The yellowish green indicator LED in my electronic bug deter flickering « Reply #2 on: September 02, 2010, 05:12:55 AM » Author: dor123
@Medved: So my amber LED nightlight in this picture: http://www.lighting-gallery.net/gallery/displayimage.php?pos=-42281 may also flickers with the mains since it is flickers 100hz like. Right?
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.

	Re: The yellowish green indicator LED in my electronic bug deter flickering « Reply #3 on: September 02, 2010, 04:18:07 PM » Author: Medved
Yes. The statement "They are DC devices" mean, then they work only for one current polarity, but does not tell anything about the current being pulsed or not...
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	Re: The yellowish green indicator LED in my electronic bug deter flickering « Reply #4 on: September 03, 2010, 02:43:45 AM » Author: dor123
@Medved: Thanks. I always thought that converting the current to low voltage DC, automatically eliminate the mains frequency flickering and as so, any LED flickering was thought by me as a result of a pulsed DC that isn't related to the mains frequency. But now, i know that the mains frequency is seperately filtered by a filtering capacitor. However, i found that my Hyundai LED emergency lighting, do have the filtering capacitor for its charging indicator red LED, because it isn't flickers.
« Last Edit: September 03, 2010, 02:55:21 AM by dor123 »		Logged

I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.