Beginner2–4 h (estimate)6 parts

Single-axis light tracker

Two LDRs and a servo turn a small panel toward the brighter side.

Overview

Two light-dependent resistors sit either side of a small divider on a servo-mounted plate. When one side is brighter, the board turns the servo toward it until both readings match, a simple feedback loop you can tune with a deadband and a gain.

You will learn

· Voltage dividers and analog readings
· Error = left − right as a control signal
· Proportional control with a deadband
· Servo pulses (PWM) in practice

Parts list

Part (generic)	Qty	Note
Arduino Uno-compatible board (5 V logic)	1
Light-dependent resistor (LDR)	2
10 kΩ resistor	2
Micro servo (SG90-class, 5 V)	1
Small card or plastic plate with a divider wall between the LDRs	1
Breadboard and jumper wires; 5 V supply for the servo	as needed

Generic part names only. Pinouts and logic levels vary between modules of the same type, so check the documentation of the exact module you have.

Tools

· USB cable and the Arduino IDE
· A torch or phone light for testing
· Hot glue or tape

Safety

· Power the servo from a suitable 5 V supply with a common ground.
· Do not point it at the sun for long through lenses; this is a learning model.

Learn the ideas first

Full build

01Build two voltage dividers and read both LDRs
02Mount the LDRs with a divider wall on the servo
03Compute the error and add a deadband
04Proportional tracking and gain tuning
05Add limits and smoothing

Checking your account…