Wednesday 4 May 2011

How to make a variable power supply using LM317

 



        LM317 - 3 Terminal Positive Adjustable Regulator
    • Output range             -        1.2V - 37V 
    • Current capacity       -         1.5A 
    • Vout                           -        1.25 (1 + R2 / R1) + I adj * R2.                   ( I adj * R2 is neglected ) 
    • Package                     -        TO220 
    • Line regulation          -         0.01% 
    • Load regulation         -         0.1%                           
             *reference voltage - 1.25V


             Circuit


      *C2 - 10uf - 470uf 50V is better.( Electrolytic capacitor )
      *C1 - 0.1uf - Ceramic capacitor.
      *R1 must be 240R.( 0.125W)
      *R2 linear potentiometer.
      *Diode 1N4007 can be connected across Vout and Vin. 
        ( A of 1N4007 to Vout and K to Vin. )
       








      2 comments:

      1. im just wondering, and want to learn , can you please explain why is that in R2 the higher value of resistor in ohms produce more increase in voltage in adjust pin of LM317. thank you so much

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