On 8/27/2012 1:55 PM, alan smith wrote:
>   Friend has me thinking about this...if you take 110VAC and half wave re=
ctify it, your going to end up with around 150VDC peak, so with the correct=
 resistor(7k-8K) it should drive a standard LED OK?  Guess I've never reall=
y thought about driving it directly from AC.  Yes..I know, its non-isolated=
 so its at the AC potential and a shock hazard.  Without a capacitor, you w=
ill see flicker on it as well of course.
>
>
This is one of those things that can be done but shouldn't be done.=20
Really to do it right the cost is pretty high compared to just using DC.=20
Capacitors at the rated voltages are not cheap, at least for the good ones.
A .47uf , 250V cap and a 1K, 1W resistor in parallel with each other and=20
the LED connected in series across that connection  will work for=20
powering LED.  I have seen bridge rectifiers built out of LED for low=20
voltage demonstrations.

Mark

--=20
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