03-Sensor & Aktuator

Sensors and Actuators

The lesson introduces two types of electronic components used in Arduino-style projects: sensors, which detect conditions or measurements, and actuators, which produce an action such as light or sound. The instructor begins with an Islamic greeting and a brief prayer.

1. LDR Light Sensor

An LDR (light-dependent resistor), or photoresistor, detects light intensity. A common use is automatic lighting: streetlights can switch off when it is bright and turn on when it is dark.

The lesson explains two ways to read an LDR:

• Digital output (DO): Provides one of two states—HIGH or LOW—and behaves like a switch. The example uses it to classify the environment as light or dark.
• Analog output (AO): Provides a range of readings, allowing more precise thresholds. The example code converts the analog reading into voltage, then estimates resistance and light level in lux. This lets the user choose how dark or bright it must be before the program responds.

Wiring and Code Examples

• For the digital example, connect the LDR module’s DO to Arduino pin 2, VCC to 5 V, and GND to ground. The AO pin is unused.
• For the analog example, connect AO to an analog input, shown as A0. The digital output is unused.
• Both examples also use an I²C LCD: SDA to A4 and SCL to A5, along with power and ground. The code initializes the LCD and its backlight, reads the sensor, and displays information such as “light” or “dark.”
• The demonstration uses example thresholds to show the difference between the two approaches. Analog readings allow the threshold to be adjusted more flexibly than a simple digital reading.

2. Ultrasonic Distance Sensor

An ultrasonic sensor measures distance by sending out a sound wave and detecting its echo. The time between sending and receiving the wave is used to calculate distance.

Wiring and Program Logic

• Connect VCC to 5 V and GND to ground.
• Connect Trigger to pin 3 and Echo to pin 2 in the example.
• The program briefly activates the trigger, reads the echo duration, and converts it to centimeters using the relationship described in the lesson: duration × 0.034 ÷ 2.
• The example turns on an LED when an object is less than 100 cm away and turns it off when the object is farther away. It also prints the measured distance to the Serial Monitor.
• Arduino’s built-in LED on pin 13 can be used for a simple output test when a separate LED is not available.

The instructor relates this type of sensor to vehicle parking aids, which can use distance readings to signal when an obstacle is close.

3. Actuators: LEDs and Buzzers

An actuator responds to a program’s output by producing an effect. The lesson names LEDs and buzzers as examples.

• LED: Used in the demonstrations as a visual indicator, such as switching on when a measured distance is below a threshold.
• Buzzer: The instructor distinguishes between:
  • Active buzzers, which produce a fixed tone when powered.
  • Passive buzzers, whose frequency can be controlled to make different notes or sounds.
• A Simon-style game is mentioned as an example that uses a passive buzzer. Players listen to tones and respond by pressing the corresponding buttons.

The instructor also notes that other sensors, such as PIR and DHT sensors, can be explored separately.

Speakers and Sources Featured

• Instructor/teacher: Presents the lesson, explains the components, and walks through the wiring and code examples.
• Students/participants: Occasionally ask questions or respond during the lesson; no individual names are given.
• Simulator and code examples: Demonstrations use simulated LDR, ultrasonic sensor, LCD, LED, and buzzer setups. These are instructional examples rather than separate speakers.