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decrease voltage from 5 volts to 1.5; voltage regulator or resistor? — Parallax Forums

decrease voltage from 5 volts to 1.5; voltage regulator or resistor?

markmcleod50markmcleod50 Posts: 27
edited 2004-11-15 08:22 in General Discussion
i am trying to decrease the voltage coming from my demo boards i/o pin from 5 volts to 1.5 and am unsure how to do this. would i use a 3 pin voltage regulator or a resistor? if i would use a resistor, how would i calculate the resistance needed to go from 5 volts to 1.5, or is resitance strictly a current thing? thanks for the help, mark

Comments

  • Guenther DaubachGuenther Daubach Posts: 1,321
    edited 2004-11-15 08:22
    Hi,

    using a resistor means that the voltage across the resistor would be 5 - 1.5 = 3.5 Volts. The formula to calculate the resistor is R = 3.5 / I. As you can see, the resistor value is a function of the current flowing through the resistor, and whatever device is connected to the other end of it. Using a resistor only makes sense when the connected device draws a constant current. Otherwise, the 1.5 Volts would not be stable. In this case, a voltage regulator would be the better solution, or - maybe - a Z-diode.

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