I have managed to solder 36 white LEDs in series. I connected them to 120 volts for a few seconds at a time and they seem to light up, flicker a lot and did not burn. My goal is to have a large number of series LEDs in series to use it with either a 120 or 220 volt AC source or both. I want them to be as energy efficient as possible, use a limited amount of extra parts, keep cost down and have the longest service life time as possible, up to the 50 and 100 thousand hours that this technology advertises ! Having the LEDs flicker a lot/significantly (60 Hz ?), I wanted to connect them to the 120 volt source using a bridge rectifier. I connected the leds to the + and - sign of the square bridge rectifier (one part) I bought from Radio Shack (400 volt rating) and the alternative source current to the two ~ signs on the rectifier ! It made a flame, loud noise and killed the electrical circuit in the wall flipping the circuit breaker in the breaker box. I also constructed a bridge rectifier with four 1000 volt rated rectifying diodes and had the same thing happening ! Can anyone give me some hints or ideas on how to make use of the bridge rectifier ? I am trying to limit the use of resistors and capacitors for cost and energy efficiency reasons and reduce the amount of work time/complexity needed to put these long led strings together, but I would like to learn more about the benefits and disadvantages of other designs as well.