PAGE 083 OF 150 · TIMERS, FLASHERS & DIMMING
PWM Dimming Explained
A higher duty cycle looks brighter.
LED SYMBOLTriangle points from anode to cathode; the arrows show light leaving the part.
Why dimming works
The eye averages fast flashes. At a duty cycle of 25 percent, the average current is a quarter of the on-current, so the LED looks dimmer.
Perceived brightness
Human vision is not linear, so a 50 percent duty cycle looks brighter than half. Applying gamma correction, often with an exponent near 2.2, gives smoother-looking fades.
Hardware
A microcontroller pin supplies only a small current, so drive bigger LEDs or strips through a transistor or logic-level MOSFET. Boards commonly offer 8-bit PWM, with values from 0 to 255.
REMEMBER
Switching an LED on and off quickly can look like steady dimmer light.Try it yourself
Sketch the circuit on paper first, calculate the values, then build it on a solderless breadboard using a low-voltage supply. Measure with a multimeter before you make anything permanent.
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