Sensors and actuators

Sense the world and act on it.

📖 Key ideas

Common sensors: temperature (DHT11/DHT22), ultrasonic distance, PIR motion, soil moisture, gas (MQ-2), light (LDR).
Analog sensors give varying voltages; digital sensors give on/off or data.
Actuators: relays, motors, servos, buzzers, LEDs.
Relays switch high-power devices safely.
Calibrate sensors for accurate readings.

💡 Real-life example: Sensors are the five senses; actuators are hands and legs.

DHT11Temperature and humidity sensor

PIRMotion sensor

RelayElectrically controlled switch

ServoMotor with precise angle control