Electronics > Beginners

Why Cheap LED Lights Keep Glowing

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Lucky-Luka:
Hi all
I've watched this funny video about a strange (at least for me) phenomena involving even some led lights in my house: they glow even when I turn off their swithes!

At the end of the day I haven't understood the part at 7:00
The output voltage can rise the input voltage? has he said that? I couldn't understand his pronunciation.
So why do those LED keep glowing?
Can somebody help me to understand better?
Cheers

ataradov:
"The output voltage can rise with the input voltage".

Even open switch and wires attached to it have some capacitance. It is not big, but it dos not matter, capacitor in the bulb will charge and there is nothing to discharge it, except for the LEDs.

radiolistener:

--- Quote from: Lucky-Luka on July 06, 2019, 09:17:26 pm ---So why do those LED keep glowing?
Can somebody help me to understand better?

--- End quote ---

because when you touch it, your body will turns into one plate of the capacitor. And the second plate of this capacitor is mains wire in your room (or may be ground). So, the LED is connected through ballast capacitor. This capacitor has too small capacitance, but it is enough for glowing. And this is why it glowing.

You can replace your body with a long wire, so there will be capacitance between this wire and ground (or other mains wire).

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