The primary goal, a blinking LED is achieved by simply using big enough resistors as current set for the LED and connect them to AC line voltage. 2 LEDs in reverse to each other are used for:
- utilize both half waves of the AC line.
- not risk the full AC voltage in reverse across a single LED.
Here in Canada we have 120V, 20KOhm deliver a nice 6mA to a red and green LED. To be really safe, 2 resistors are used. And to be even safer, the initial test was done outside on good solid Nova Scotia bedrock, in case the LED would blink only once but violently bright.
More pictures in the gallery show the 120V AC across the whole circuit and ~2V across the LED with either red or green LED on. Theory and practice agree for once. The part list will show parts available at Mouser to recreate this setup.
Cheers and Good luck.