Lm3915 Calculator: Updated [portable]

I can provide the exact resistor values or calculate an updated precision schematic for your project. Share public link

Before using the calculator, identify your project requirements: The peak voltage of your audio or analog signal. Desired LED Brightness ( ILEDcap I sub cap L cap E cap D end-sub

Using these formulas, you can customize your circuit for different input signals. Target Application Max Input Signal VREFcap V sub cap R cap E cap F end-sub Line Level Audio High Range Display lm3915 calculator updated

VREF≈1.25×(1+R2R1)cap V sub cap R cap E cap F end-sub is approximately equal to 1.25 cross open paren 1 plus the fraction with numerator cap R sub 2 and denominator cap R sub 1 end-fraction close paren LED Current Formula ( ILEDcap I sub cap L cap E cap D end-sub

To configure the LM3915, you must determine the values of two external resistors, R1cap R sub 1 R2cap R sub 2 . These resistors set the internal reference voltage ( VREFcap V sub cap R cap E cap F end-sub ) and the current flowing through the LEDs ( ILEDcap I sub cap L cap E cap D end-sub 1. Reference Voltage Formula I can provide the exact resistor values or

Now, rearrange the simplified reference voltage formula to isolate R2cap R sub 2

R1=12.5ILEDcap R sub 1 equals the fraction with numerator 12.5 and denominator cap I sub cap L cap E cap D end-sub end-fraction Target Application Max Input Signal VREFcap V sub

cap V sub cap R cap E cap F end-sub equals 1.25 cap V center dot open paren 1 plus the fraction with numerator cap R 2 and denominator cap R 1 end-fraction close paren plus open paren cap R 2 center dot 80 mu cap A close paren