): The total reference voltage, which determines the full-scale input voltage required to light up the 10th LED, is calculated using:
R2=1200×(4−1)cap R sub 2 equals 1200 cross open paren 4 minus 1 close paren
4.2 Input Conditioning
Input your desired LED current into the calculator. The tool rearranges the current formula to solve for R1cap R sub 1
4−1=R2R1⟹3=R28204 minus 1 equals the fraction with numerator cap R sub 2 and denominator cap R sub 1 end-fraction ⟹ 3 equals the fraction with numerator cap R sub 2 and denominator 820 end-fraction lm3915 calculator updated
R_LED = (Vcc - Vf_LED) / I_LED
Unlike its sibling the (which is linear) or the LM3916 (which mimics a VU meter), the LM3915 has a 3dB/step logarithmic response. ): The total reference voltage, which determines the
The LM3915 remains a compact, low-cost solution for audio level indication. By pairing it with modern input conditioning, AGC, and optional MCU control, a compact "calculator-style" meter can offer accurate, configurable, and power-efficient metering suitable for hobbyist and professional applications.