100K Ohm NTC 3950 Thermistor
100K Ohm NTC 3950 Thermistor Detailed Explanation
What is it?
A NTC Thermistor is a type of resistor whose resistance changes with temperature.
NTC means Negative Temperature Coefficient, which means:
As temperature increases resistance decreases
The 100K 3950 specifies its key characteristics.
Meaning of 100K 3950
1. 100K Ohm
Resistance at 25C = 100,000 (100k)
2. 3950 (Beta Value)
A constant that defines how resistance changes with temperature
Based on the Steinhart'Hart equation
Higher Beta steeper resistance change
ts charge carriers
This changes resistance
Behavior:
Cold High resistance
Hot Low resistance
Temperature'Resistance Relationship
Where:
R(T)R(T)R(T): Resistance at temperature TTT
R0R_0R0: Resistance at reference temperature T0T_0T0 (usually 25C)
BBB: Beta value (3950)
TTT: Temperature in Kelvin
Typical Circuit (Voltage Divider)
To use with a microcontroller:
VCC[ Fixed Resistor ]-----> Output (to ADC)[ Thermistor ]GND
Output voltage changes with temperature read using ADC
Key Specifications
Resistance: 100k @ 25C
Beta value: 3950
Temperi
Accuracy: typically 1% to 5%
Important Characteristics
1. Non-linear Response
Not linear like digital sensors
Requires calculation or lookup table
2. High Sensitivity
Very sensitive to small temperature changes
3. Fast Response
Small size quick thermal response
Applications
Temperature measurement
Battery temperature monitoring
CPU thermal control
HVAC systems
Automotive sensors
Power supply protection
Advantages
Low cost
High sensitivity
Small size
Fast response
Limitations
Self-heating can affect readings
Example Use with Arduino
Steps:
Create voltage divider
Read analog value (ADC)
Convert voltage resistance
Use equation (or library) temperature
Real-Life Example
In a laptop:
Thermistor detects CPU temperature
Resistance drops as temperature rises
System increases fan speed
Practical Tips
Use a precision resistor (1%) in voltage divider
Avoid placing near heat sources unless intended
Use averaging in