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Re: Classic MPC C-3PO and R2-D2 uber detail build

Each colour LED has its own Voltage drop. You should be able to find a LED chart on line. Most LED's draw
20ma of currentand as was said before red drops 2.0v and blue drops 3.6v. You can not measure the resistance of a LED directly since they are an active device. You can measure the voltage drop across the LED though with a voltmeter.
To calculate the series resistor for the LED. where S= the voltage applied to the LED (volts)
V led = the voltage drop of the LED (volts)
I led = the spec current for the LED (amp)

R = (S - V led) / I led

I hope this is of some help.

Jim

<blockquote data-quote="Papermodder" data-source="post: 129607" data-attributes="member: 12832">Re: Classic MPC C-3PO and R2-D2 uber detail buildEach colour LED has its own Voltage drop. You should be able to find a LED chart on line. Most LED&#039;s draw20ma of currentand as was said before red drops 2.0v and blue drops 3.6v. You can not measure the resistance of a LED directly since they are an active device. You can measure the voltage drop across the LED though with a voltmeter. To calculate the series resistor for the LED. where S= the voltage applied to the LED&nbsp; &nbsp; (volts)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; V led = the voltage drop of the LED&nbsp; (volts)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; I led = the spec current for the LED (amp)&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp;&nbsp; R = (S - V led) / I ledI hope this is of some help.&nbsp;Jim</blockquote>

[QUOTE="Papermodder, post: 129607, member: 12832"] [b]Re: Classic MPC C-3PO and R2-D2 uber detail build[/b] Each colour LED has its own Voltage drop. You should be able to find a LED chart on line. Most LED's draw 20ma of currentand as was said before red drops 2.0v and blue drops 3.6v. You can not measure the resistance of a LED directly since they are an active device. You can measure the voltage drop across the LED though with a voltmeter. To calculate the series resistor for the LED. where S= the voltage applied to the LED (volts) V led = the voltage drop of the LED (volts) I led = the spec current for the LED (amp) R = (S - V led) / I led I hope this is of some help. Jim [/QUOTE]

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