LM 317 calculations

    

     Output voltage	
     
     Resistor R1	
     
     Resistor R2	
     
     			
    
   

The easiest way to get things cracking with the LM317 is to mount a 1 Kilo Ohm potentiometer between V-out and Ground and connect the control input of the LM317 to the center tap of the potentiometer. But for all those cases where you just need a fixed voltage you can use the resistance calculator shown here.

Remember!

• The filter capacitor should not be lower than 1000 uF
• Watch the voltage rating for the capacitor
• The LM317 likes to have some headroom between Vin and Vout; 2.5 Volts at least!
• Mount the LM317 on a metal plate for a heatsink
• The LM317 does not like electrolytic capacitors at its output!

Page created 20 August 2009,

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