Re: LED\'s and AC Power
We have converted a 12v AC Halogen desk lamp to White leds sucesssfully, on a trial and error basis, this is what i learned.
Ac voltages are not what they seem, they are RMS, which mean root means square, or some doodely

anyways that means the AVERAGE of the ac sine wave is the listed voltage, not the possibilities for volatages which can toast an led.
the lamps have 12v tranformers in them for the 12v halogen light Approx 14.4v no load.
so one lamp with 4 lights per bank max possible for the leds would be 16v right ?
well not if the sine wave of the ac is going over that, so the adding of a cap could blend out some of the sine , i donno.
anyways ONE of the desk lamps has always gone through halogen bulbs by burning them out after a month of use, but the other burned the halogen lamp normally.
so the one that didnt burn up the 12v halogen lamp has been working with banks of 4leds per row now for MONTHS, uses 1/10 the power of the halogen, is obnoxiously blue and flickers just a bit, it very directional and only puts out about 1/2 the actual light of the halogen it replaced.
the other one that always ran the halogen lamp hotter, toasts its 4 bank of leds in about 2 months of use, and might have worked with 5 per bank, but 5 per bank was low voltage and it looked quite dim, this one has been scrapped as a good idea , and was returned back to halogen.
the other thing about ac is it is only on 1/2 the time for Diodes (leds) so it flickers lots with only one bank, by parellelling 2 banks with reversed polarity this flicker was reduced to acceptable levels.
so for every other set of 4 leds the next set added was reversed.
the total led count in the working forever AC lamp conversion is 28white leds power consumption at the plug is approx 2watts
small power surges hit this lamp OFTEN and it has not been a problem YET
so there is one ac that worked
IF i was to attempt this with full 115-120ac i would start with 80 leds in two banks 40 then 40 reversed in polarity, the problem with this is the 120$ cost and the resultant flicker would not work better than a nice compact florescent bulb at 9$
