1. STARTER They all detect something and then respond But how?
What is the function of each of the electronic products shown below and what do they all have in common?
They all detect something and then respond
But how?
Plant Water
Detector
Solar Garden Light
Electronic Thermometer
Electronic Drum
Blood Glucose Level Detector

2. WHAT SENSOR?
What is the sensor used in each of these electronic products and what does each detect?
LDR
A Light Dependent Resistor is a type of resistor whose resistance changes according to light.
Bright Light – low resistance (≈1KΩ)
Darkness – high resistance (≈1MΩ)

3. Thermistor WHAT SENSOR?
A thermistor is a type of resistor whose resistance changes according to temperature.
High temperature – low resistance (≈70Ω)
Low temperature – high resistance (≈1KΩ)

4. Moisture Sensor WHAT SENSOR?
A Moisture Sensor is a type of resistor whose resistance changes according to moisture.
Wet – low resistance
Dry – high resistance
They tend to be made from two copper or brass rods or as a PCB

5. Piezo Electric Transducer
WHAT SENSOR?
Piezo Electric Transducer
A Piezo Electric Transducer works in a very different way to the other sensors you have learnt about today in that it produces a voltage in response to any vibration

6. WHAT SENSOR?
Biosensor
HOMEWORK: Topic 23