Sensors
Table of Contents
Push buttons
This momentary push button will connect the terminals on the two sides when pressed down. The button can be used in a breadboard or prototype board. The pinout button below shows the pinout of the button.
Microphone
This electret microphone is a sensor that turns soundwaves into a voltage signal. It can be used with the example schematic. You may need to amplify the signal using an opamp depending on the application.
NTC
This sensor is a variable resistor that varies its resistance with the temperature of the bead. At room temperature (25 degrees Celsius) the resistance is 100 kΩ. The resistance goes up as the temperature drops and vice versa. The exact T/R curve can be calculated or read from a table in the datasheet. The curve can be calculated with parameters found in the datasheet and the formula below.
To get a voltage signal proportional to temperature, the NTC may be used in a voltage divider.
Example Schematic Formula Datasheet
LDR
This light dependent resistor can be used to make a system light sensitive. The resistance of the LDR changes with illumination, where the resistance drops when illuminated and vice versa. The datasheet provides several suggested uses depending on the application.
Photodiode
The photodiode contains a P-N junction that generates an electrical current when photons hit it. In layman’s terms; it generates electricity with light, just like a solar panel does. Typical applications for a photo diode are for example CD players, smoke detectors and IR receivers.
Random sensor
There are 4 different kinds of sensors: The SHT20, HC-SR04, MPU6050, and an RFID kit. You should find you have only one of these, a deliberate choice. You can use these for your first projects for inspiration. Feel free to visit the STORES for sensors, if no one in your group owns a sensor you would want to use.
SHT20
The SHT20 is a digital temperature and humidity sensor. Using the I2C protocol the values can be read out on a microcontroller. In the datasheet there is also a manual included which explains how to read out data.
HC-SR04
The HC-SR04 is an ultrasonic module, with which you can measure the distance to objects. Simply sending a pulse will return an echo signal proportional to the distance.
MPU-6050
The MPU-6050 is an accelerometer and gyroscope module, which can be used to measure acceleration up to 16g and angular velocity up to 2000°/s. The measurements can be read using the ubiquitous I2C protocol.
RFID Kit
The RFID kit consists of a card, a tag and an RC522 RFID module, which allows reading and writing of the cards. Using the SPI communication protocol data can be stored to and written to the accessories.
Piezo buzzer
This buzzer has a piezo element inside. This crystal element expands and contracts by applying a voltage to it. Supplying a square wave to the buzzer will generate a sound.
Current amplification may be nessecary to drive the buzzer. The circuit found below may be used to drive the buzzer.