2007-02-14 21:02:13 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Use a rectifier.
2007-02-14 21:12:01 · answer #1 · answered by ag_iitkgp 7 · 0⤊ 0⤋
You will need to use a full-rectifier circuit (i.e. 4 standard diodes) to get the voltage into DC, then use a potential divider circuit (to split off the correct potential of how many volts you need for the LED - normally between 5 and 15 volts), otherwise the LED will not function correctly.
I think you can now get LED's that will work with AC voltages (although they are probably massively expensive), I would try contacting 'MAPLIN', Farnell or RS Components to see if they have something suitable.
Hope this helps.
2007-02-15 05:16:49 · answer #2 · answered by Doctor Q 6 · 0⤊ 0⤋
Most LEDs don't want more than about 1 volt or so across the diode and don't want AC at all. So, you will need some sort of step-down AC to DC convertor. Seems like a shirt-pocket-full of simple components would do the job.
2007-02-15 05:11:54 · answer #3 · answered by ZORCH 6 · 0⤊ 0⤋
since it takes about .6 volts at a few milliamps to light an LED, figure:
I=current in milliamps= 50 milliamps=0.050
v=.6v
R= ?
.6/.05= 12 ohms LED is 12 ohms when lit. LED needs a current limiting resistor in series with it to go across 220vac. since LED is a rectifier RMS volts across it will be .707 x 220=155v
155v/.050 amps= 3100 ohm resister in series with led.
.050 x 155= 7.75 watts
of course, i could be wrong
2007-02-15 05:23:51 · answer #4 · answered by oldguy 6 · 0⤊ 0⤋