V Regulator and Dimmer

Discussion in 'General Electronics Chat' started by Metalfan1185, Dec 22, 2008.

  1. Metalfan1185

    Thread Starter Active Member

    Sep 12, 2008
    I have 2 seperate questions for the board here.

    1) What can i use to Dim a cluster of LED's all at about 13.8V to 12V for the Voltage. I thought i could use a Variable resistor and a MOSFET, but im not sure now. because i think it was mentioned that it's bad to drive a MOSFET half-assed so to speak.

    2) Which Value Variable Resistor should i use on the ground pin of a LM317 to make the output Voltages Variable between 0 or 1V to 24V? (the input is 24V+) I would like to make decent adjustments with a single turn Potientiometer.

    Thanks Guys.
  2. bertus


    Apr 5, 2008

    For question 1) You can dim back to 12 Volts using PWM.
    This will switch the mosfet totaly on or off.

    For question 2) the LM317 will work from about 1.2 volts and up.
    See the datasheet.