Op-Amp Gain — LED Driver
Non-inverting driver
Enter input, gain resistors, LED specs and supply; gain, output and limiting resistor appear live.
Driver
How to use this calculator
A non-inverting op-amp sets its output to Vout = Vin·(1 + Rf/Rg). An LED is then driven from that output through a current-limiting resistor: Rlim = (Vout − VF) / ILED. Enter the input, the gain resistors, the LED forward voltage and current, and the op-amp supply; the gain, output voltage, and limiting resistor appear live. If Vout would exceed the supply, the calculator clamps it and flags the condition.
What it means in a real circuit
For Vin = 1 V, Rf = 20 kΩ, Rg = 10 kΩ the gain is 3, so Vout = 3 V. With a 2 V LED at 10 mA the limiting resistor is (3−2)/0.010 = 100 Ω. The op-amp gives you a controllable, gain-set LED brightness from a small input signal. Keep the required Vout within the op-amp's rail (minus its output swing), or the LED will be dimmer than calculated — that's what the clamp warning tells you. Use this for signal-driven indicators, VU meters, and dimming circuits.