LED (5mm) with A/C supply

[shahbaz.ele]

dear all
can i use LED 5mm with A/C supply just to show the light present or not.
Should i use 1Watt resistor of 4.7K or other thing.

 

[neddie]

What is the voltage of your ac supply? Mains(220V or 110V or something else). A series resistor will work , but will have to be sized correctly. 220V use a 22K 3W resistor.
That will give you a little under 10mA. 10K for 110 volts will work. Put a reverse diode across the LED to protect it during the negative going portion of the waveform.
Cheers
Neddie

 

[shahbaz.ele]

Thanks neddie,
I am using 220VAC, I will try this then discuss problem with you.

 

[arupbsk]

I have a similar setup inside my household voltage stabilizer. One RED/GREEN LED in 220VAC with a 100K 1/2W series resistor. It doesn't give much brightness but as an indicator with total wattage below 0.5W it's great.