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april
Joined: 10 Mar 2005
Posts: 4
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 Posted: Sun Feb 29, 2004 11:16 am Post subject: Led circuit help????? |
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| Design and build a circuit that will allow you to apply 13.8 Vdc, while the LED only receives 3 Vdc.What size resistor should i use? |
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nigyar_98
Joined: 11 Mar 2005
Posts: 3
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| Posted: Wed Mar 17, 2004 12:57 pm Post subject: Led circuit help????? |
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| use a voltage divider circuit.http://en.wikipedia.org/wiki/Voltage_divider |
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loki_only1
Joined: 26 Aug 2007
Posts: 5
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| Posted: Sat Apr 03, 2004 2:38 pm Post subject: Led circuit help????? |
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| To fully answer your question, you will need to specify the current through the LED. A typical current might be 20mA. Then you will need a resistor in series with the LED which will drop (13.8 - 3) = 10.8 Volts at 20mA . Using V = IR , R=10.8/.020 = 540 Ohms. |
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