A simple yet effective circuit for a single LED on AC Mains....
Step 1: Parts & Assembly
1. An LED - 5mm or 10 mm of any colour
2. A diode, preferably 1N 4007
3. A resistor of 1 watt rating, of value anywhere from 20 kilo ohms upto 100 kilo ohms.
4. A two pin male plug (hollow)
Lower resistor values will give more brightness and higher values will prolong LED life. So choose the tradeoff, depending on requirement.
Lower wattage of resistor like 1/2 watt or lower will not do and may burn since they are meant for 6v DC circuits, not for 220v AC Mains.
1. Connect black anode of diode to negative of the led.
2. connect the resistor to the positive of the LED.
3. Connect the free ends of the diode and resistor to the male pins.
Done. See the attached pic for clarity.
Another circuit with the diode connected "across" the LED is also attached. A bulb base adaptor is used instead of a male pin.
It should work on 110v AC as well as 220v AC Mains systems.
It will also work on any battery!!
Once again, read "Important" first line, in case you missed it....