Anonymous asked in Science & MathematicsPhysics · 1 decade ago

How can I reduce a 12VDC 1.5A power supply to power one 3V LED?

1 Answer

  • 1 decade ago
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    The only way 'easily' to do it with a DC supply is use a resistor in series.

    You first need to find resistance of your LED (usually small), if its quoted fine, if not you will need a ammeter. Use two pencil cells(in series) and an ammeter with your LED , to measure current, divide (3V / current) to get resistance.

    Now since you require about 9 Volts to dissipate in your resistor,...

    you will need a resistor 3 times the resistance of your LED.

    Quoted ampere (1.5A), is usually a max you can draw from that 12V power supply you can ignore that.

    You can also try guess work, but might burn few of your LED's

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