Hi, Javier --
Light-emitting diodes have a voltage drop of about
2 volts, and the typical variety wants no more
than 20 milliamps. So, 10/.02 = 500, or a 470 or
510 ohm resistor (1/4 watt OK) is what you want.
Regards
Fred Fillinger, A063
> Barahona Alonso, Francisco Javier wrote:
>
> Dear friends,
>
> Months ago somebody advised me about the
> possibility of substituting the alternator
> warning lamp (3W, 12V) for a diode plus a 480
> Ohms resistor. Making calculations I obtain
> that I need a resistor of 48 Ohms instead:
>
> R = (V
2)/P = (12
2)/3 = 48
>
> I do not know which is the resistance of the
> diode. Could somebody confirm me which of both
> resistors, 48 or 480 Ohms should I use?
>
> Best regards.
>
> Javier Barahona (Classic #187)
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