Designing a logarithmic VU meter or audio level indicator with the requires precise resistor selection to set your reference voltage and LED brightness. Since this IC uses a 3dB/step logarithmic scale, it's perfect for audio projects.
LM3915 IC based Audio Level Display & Its Working - ElProCus lm3915 calculator updated
Older calculators never did that, leading to many melted chips. Designing a logarithmic VU meter or audio level
Furthermore, selecting resistor values for R1 and R2 to get a specific LED brightness and a specific input range (e.g., 0dBm at 0.775V RMS) required solving simultaneous equations involving LED current and reference current. Furthermore, selecting resistor values for R1 and R2
This means each LED lights up when the input voltage increases by a factor of roughly 1.41 (the square root of 2). This is perfect for audio signals, where our ears perceive volume logarithmically.
The new calculator allowed Leo to instantly solve the three biggest challenges of his build: