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Posted: **Sun Jul 29, 2012 7:56 pm**

Where could I extract 3v to power the on off switch illumination? I guess I need a resistor as well. Any ideas?

Posted: **Sun Jul 29, 2012 9:52 pm**

Is it a LED illuminated switch? You can use 5V via a current limiting resistor.

Posted: **Mon Jul 30, 2012 7:43 pm**

Thanks Dmitri. What size would the resistor be?

Posted: **Mon Jul 30, 2012 9:02 pm**

Depends on the LED's specs.

R = (5V - LED's Forward Voltage) / (Desired LED's Forward Current)

Desired LED's Forward Current depends on the LED's specs and desired luminance intensity/power consumption.

See http://ledcalc.com/

Posted: **Mon Jul 30, 2012 9:37 pm**

Thanks that looks useful.

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3v supply

3v supply

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