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LM317 LM338 Calculator



This LM317, LM338 calculator software is used as a tool to determine the value of the voltage adjusting resistor needed to assign the output of an LM317 to an allocated degree. Normally R1 is 220 ohms or 240 ohms, however it could very well be a different value for instance 150 or 470 ohms. Go with a value for R2 and click the "Calculate" button. The LM317 output value is displayed in volts. Take into account that the input voltage to the LM317 is required to be a minimum of 1.5v higher than the output voltage.
LM317 Voltage Calculator

Calculate LM317 Resistor Values


R1 resistor
R2 resistor Output Voltage


Need Help? Please leave a comment, I'll get back soon with a reply!

Comments

  1. Hi hello sir swagatam..let me ask you.. i was using a lm317t for my variable supply but the problem was my 220ohmsRes.is burning..my main supply V is 48v? Pls help me I need your expertise

    ReplyDelete
    Replies
    1. hello mark, 48V cannot be used as the input for a LM317T IC, 40V is the max limit according to its datasheet.

      you can try LM317HV series for a 48V input

      you can use the above software for determining the correct R1/R2 ratio for getting an output equivalent to around 40V

      Delete
  2. Sir swagatam thanks alot.. God bless you

    ReplyDelete
  3. hello sir sawgatam, I need to biuld a power supply with a variable output. any advices?

    ReplyDelete
  4. i find difficult to make a circuit inductor of a certain value of inductance, how can i make one practical at home

    ReplyDelete
    Replies
    1. for an air cored inductor, you can try using the following software

      http://www.homemade-circuits.com/p/inductance-calculator.html

      Delete
  5. Hai sir....
    I need DC Variable voltage circuit...
    By using potentiometer sir....

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  6. Sir I have made a voltage regulator circuit using LM317, and used a 10K pot at R2. But my pot is getting burnt as soon as i am trying to decrease the output voltage after a certain level. Plz help me solving this.

    ReplyDelete
    Replies
    1. It could be happening due to any of the two reasons, either you have made a wrong connection with the IC pins or the IC itself is faulty...the second reason looks more likely.
      a pot will burn only when there's a short circuits across its terminals and in your case this may happen if the ADJ pin of the IC is short circuited due to a faulty device

      Delete
  7. Hlw sir, I have made this voltage regulating circuit using LM317. A transformer of 12V. I have used a 10K pot at R2. But when I am trying to decrease the output voltage after a certain value my pot getting burnt. plz give a solution.

    ReplyDelete
    Replies
    1. Hi Suman, check your IC connections properly, if you are sure those are correctly wired then it could be due to a faulty or duplicate IC 317, replace it with a good one

      Delete
  8. Please can anyone help to project LM317 stabilizer. Output voltage should be 24V and current limit 1.5A. Thanks in advance

    ReplyDelete
    Replies
    1. the current will be internally limited to 1.5 amp in the IC, so that won't be an issue.

      for 24V output, make sure to use a 30V input and simply calculate the values of the R1 and R2 as suggested in the above page for getting the required fixed 24V out

      Delete
  9. I put R1 as recommended 240 Ohm and R2 is calculated 4368. Also, I found input should be 3V more then wanted output, which means 27V. Is that ok? Do I need capacitors?

    ReplyDelete
    Replies
    1. yes all your calculations are correct, the input should be minimum 27V or higher than this value upto 36V

      Delete
  10. Thanks a lot.
    Now I have to make dc dc convertor with the same specifications and input voltage between 10 and 12V. If you have any suggestions or links let me know, because I don't have experience with this.

    ReplyDelete
    Replies
    1. you mean to say you want 24V from 12V??

      In that case you can try a simple joule thief circuit as shown below, and dimension the coil accordingly:

      http://www.homemade-circuits.com/2012/10/1-watt-led-driver-using-joule-thief.html

      the collector side turns could be around 30 to 40, while the base side could be around 50, tweak them to optimize the final outcome.

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    2. Yes, input 10V to 12V needs to give stable 24V output

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    3. OK, you can try the suggestions which was mentioned in the previous comment.

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  11. Hello, I can't go below 3v when R1 is 4903ohm and R2 is 1K, I want to output 1.5v

    ReplyDelete
    Replies
    1. use R1 = 240 ohms, R2 = 50 ohms

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    2. Sorry, I forgot to mention R2 needs to be 1K because it's my adjust pot, I guess it can't be done.

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    3. you can use 1K pot, ans still get 1.5 V.....your IC may be fault

      Delete

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