sensor technology
TRANSCRIPT
Understanding and Applying Sensor TechnologyBoadu A. Charles Jnr
…a device that measures a physical quantity and converts it into a signal which can be read by an observer or by
an instrument.
Sensors
Where we can find them
• Cars (60-100 sensors)
• Phones (6-10 sensors)
• ATMs
• Homes and offices
• Airports
Examples and Applications
Sensors
Force Sensors
How it works Changes resistance when a force or pressure is applied.
Resistance is inversely proportional to the force applied.
Applications • Pressure sensor (someone standing/
sitting) • Impact testing
Sensors
Flex Sensor
How it works Detects when something is bent and measure the degree of bend.
Resistance is increase proportional to the degree of bend.
Application • Sign language translator.
Sensors
Current Sensor
How it works Detects the amount of current passing through a conductor by measuring the magnetic field generated around it.
Applications • Battery supplied applications. • Circuit protection and control. • For metering.
Sensors
IR Range Finder
How it works Uses how long it takes transmitted IR to be reflected back into the receiver to approximate its distance from an obstacle.
Has detection range of 20 cm to 150 cm.
Applications • Measure presence or absence of
an obstacle. • Measure how far an object is.
Sensors
Ultrasonic Range Finders
How it works Uses how long it takes sound to be reflected back to approximate its distance from an obstacle.
Very accurate and quite expensive. Has detection range of 2 cm to 400 cm.
Applications • Measure presence or absence of
an obstacle. • Measure how further away an
object is.
Sensors
Passive IR Sensor
How it works Used to detect whether a human has moved in or out of the sensor’s range. Senses motion
Response time and sensitivity van be tuned.
Applications • Engaging and disengaging door
locks. • Implement power management
strategy by putting of lights when room is no longer in use.
Sensors
Humidity Sensor
Temperature Sensors
How it works Measures atmospheric conditions.
Application • Used in home heating, ventilating,
and air conditioning systems, offices, cars, industrial spaces and greenhouses.
Barometric Sensor
SensorsHow it works Conducts electricity at a certain rate therefore leading to a specific level of charge flow that is associated with a specific level of pressure.
Applications • Used in aircrafts, rockets, satellites
and weather balloons to measure altitude.
Sensors
Alcohol Gas Sensor
Carbon Monoxide Sensor
Liquid Level Sensor
Soil Moisture Sensor
Vibration Sensor
Sensors
Gyroscope Accelerometer
Compass
Hall Effect Sensor
Tilt Sensor
Sensors
Geo Phone
Light SensorPulse/Heart Rate Sensor
Line Sensor
Voltage Divider and Sensor Technology
Voltage Divider
R1
R2
Vout
Vin
Voltage Divider
5 Ohm
5 Ohm
2V
4V
3 Ohm
5 Ohm
2.5V
4V
8 Ohm
5 Ohm
1.54V
4V
Sensor Connections
Vin
Vout
GND
4V
2.89V
GND
2V
5V
4V
GND
5V
2V
1.14V
Sensor-Microcontroller Connections
Pinout Classification
• 3-pin Sensors
• 2-pin Sensors
3-pin Sensors
• Vin, Vout, GND
• +, Vout, -
Sensors that have 3 pinouts by which one can connect them to any circuit or to the micro controller.
Pinout Labelling
Vin + GND -
3-pin Sensors
VinGND
Vout +
-Vout
3-pin Sensors
3V3GND
A0, A1, A2, A3, A4
3-pin Sensors
Vin
GND
Vout
const int motionSensor = A3; const int threshold = 100;
int sensorReading = 0;
void setup() { }
void loop() { sensorReading = analogRead(motionSensor); if (sensorReading > threshold) { // do something } else { // do something else } }
3-pin Sensors
2-pin SensorsMost sensors that have 2 pinouts. Sensors with 2 pin out need to be connected to a resistor.
Vin
Vout
GND
Sensor Connections
Vin
Vout
GND
Good Sensors, Bad Sensors
Good Sensors
• Sensitive to only the measured property.
• The sensor itself doesn’t influence the
measured property.
• The output should a simple function of the
measured value.
Bad Sensors
• Drift
• Noise
• Power draining
Further Reading
http://www.futureelectronics.com
Thank You