LESSONLED Series · Part 10 Also: Arduino C++ Series · 9EP.22 · 20 s

Speed knob: potentiometer + analogRead

Name: Speed knob: potentiometer + analogRead
Uploaded: 2026-10-04T07:00:00+05:30
Duration: 20 s
Description: A potentiometer (5V, wiper → A0, GND) gives 0–5 V; analogRead(A0) turns it into 0–1023, and delay(knob / 4 + 20) makes the chaser 20–275 ms per LED.

Cover of the lesson: Speed knob: potentiometer + analogRead

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// WHAT YOU WILL LEARN

A potentiometer (5V, wiper → A0, GND) gives 0–5 V; analogRead(A0) turns it into 0–1023, and delay(knob / 4 + 20) makes the chaser 20–275 ms per LED.

// LESSON NOTES

Turn a knob, change the speed 🎛️

THE KNOB: a potentiometer is a resistor track with a sliding contact (the wiper). Outer legs go to 5V and GND, the middle leg goes to A0. Turn it and the wiper gives any voltage from 0 V to 5 V. It's a voltage divider you can turn!

analogRead(A0): the Uno turns 0–5 V into a number from 0 to 1023 (10-bit, 1024 steps). 0 V = 0, 2.5 V ≈ 512, 5 V = 1023.

THE CODE: only 2 lines changed from the LED chaser. int knob = analogRead(A0); reads the knob every step, and delay(knob / 4 + 20); turns it into a wait of 20 to 275 ms.

Big number = long wait = slow. Small number = short wait = FAST. Shown at real speed.