Thermistor

 Understanding NTC and PTC Thermistors: A Guide to Temperature-Sensitive Resistors

Thermistor

In the world of electronics, temperature sensing and control are critical in many applications—from home appliances to industrial equipment. Among the most commonly used temperature sensors are thermistors, specifically NTC (Negative Temperature Coefficient) and PTC (Positive Temperature Coefficient) types.

Let’s explore what they are, how they work, and where they are used.

🔍 What is a Thermistor?

A thermistor (short for “thermal resistor”) is a type of resistor whose resistance changes significantly with temperature. Unlike standard resistors that maintain a fixed resistance, thermistors are highly sensitive to temperature variations.

There are two main types:

  • NTC Thermistor – Resistance decreases as temperature increases.

  • PTC Thermistor – Resistance increases as temperature increases.

🌡️ NTC Thermistor (Negative Temperature Coefficient)

How It Works:

In an NTC thermistor, the resistance drops as the temperature rises. This happens because the increase in temperature excites more charge carriers (like electrons), allowing current to flow more easily.

Characteristics:

  • High resistance at low temperatures.

  • Resistance decreases non-linearly with rising temperature.

  • Very sensitive to small temperature changes.

Common Applications:

  • Temperature sensing in thermostats and digital thermometers.

  • Inrush current limiters in power supplies.

  • Battery protection circuits (to monitor and prevent overheating).

  • Automotive engine temperature sensors.

🔥 PTC Thermistor (Positive Temperature Coefficient)

How It Works:

A PTC thermistor does the opposite: its resistance increases with temperature. At a certain point (called the Curie temperature), the resistance rises sharply and can limit or stop the flow of current.

Characteristics:

  • Low resistance at room temperature.

  • Resistance increases rapidly beyond a specific temperature threshold.

  • Acts like a self-resetting fuse.

Common Applications:

  • Overcurrent protection in circuits.

  • De-icing heaters in refrigerators and freezers.

  • Self-regulating heating elements.

  • Resettable fuses in power systems and motor windings.

⚖️ NTC vs. PTC: Key Differences

FeatureNTC ThermistorPTC Thermistor
Resistance TrendDecreases with temperatureIncreases with temperature
SensitivityHigh sensitivityLower sensitivity
Typical UseTemperature measurementCurrent protection
CostUsually cheaperSlightly more expensive

🧪 Choosing the Right Thermistor

When selecting between NTC and PTC thermistors, consider the application:

  • Choose NTC for precise temperature monitoring and control.

  • Choose PTC for overcurrent protection and automatic circuit breaking.

🧠 Final Thoughts

NTC and PTC thermistors are small but powerful components that play a crucial role in making our devices smarter and safer. Whether it's protecting your laptop charger from overheating or regulating the temperature in your refrigerator, these components are quietly doing their job behind the scenes.

Understanding how they work and where they are used helps engineers and hobbyists alike create more reliable electronic systems.

Have questions or need help choosing the right thermistor for your project? Leave a comment below!

Location: Ramala, Uttar Pradesh 250623, India

Comments

Post a Comment

Popular posts from this blog

water tank motor auto on/off switch circuit diagram

Image
पानी की टंकी मोटर स्वचालित चालू / बंद स्विच  प्रस्तुत सर्किट द्वारा पानी की टंकी पूरी तरह से भर जाने के बाद टैंक की मोटर अपने आप बंद हो जाती है। और टंकी में पानी खाली होने पर मोटर अपने आप चलने लगती है।  इस परिपथ में IC 555 का प्रयोग किया जाता है। IC 555 इस सर्किट और टाइमर सर्किट दोनों में समान रूप से काम करता है। और IC सुरक्षा के लिए, हमने इसमें एक डायोड in4007 जोड़ा है। इसके अलावा इस सर्किट में 2 ट्रांजिस्टर BC548 का भी इस्तेमाल किया गया है। और एक रिले 18V का उपयोग ऑन-ऑफ स्विच के रूप में किया गया है। इस परियोजना में हमें तीन तारों को पानी की टंकी में विसर्जित करने की आवश्यकता है। +V तार को पानी की टंकी के सबसे निचले स्तर पर रखा जाना चाहिए और ic के ट्रिगर पिन 2 वाले तार को पानी की टंकी के मध्य स्तर पर रखा जाना चाहिए। और तीसरा तार जो ट्रांजिस्टर Q1 के आधार से जुड़ा है, पानी की टंकी के शीर्ष पर रखा गया है। काम करने का ढंग पानी की टंकी मोटर ऑटो चालू/बंद स्विच  ...
Read more>>

remote control switch circuit diagram

Image
Remote control switch  The circuit presented serves as a remote control switch.  This circuit is built using ic CD 4017.  A 12 volt relay is used in this circuit which acts as a switch.   by this switch you can on or oof fan, cooler, bulb and any electricity device. list of all the electrical components used in this circuit  given below. Remote control switch circuit diagram  Electronics Components list  ic CD4017  Capacitor  1uf 25v ir receiver  TSOP 1738 Transistor  Q1 bc 557 Q2 BC547  Resistance  R1 10k ohm R2 100k ohm R3 1k ohm Diode  1N4007  Relay 12v PCB BOARD  Watch full video 
Read more>>

fm transmitter circuit diagram

Image
Building Your Own FM Transmitter:  A Step-by-Step Guide Introduction: In an era where wireless communication is king, understanding the basics of radio frequency (RF) technology can be both fascinating and practical. One exciting project to delve into this world is building your own FM transmitter. In this blog post, we'll provide you with a comprehensive guide, including a circuit diagram, to create your very own FM transmitter. Whether you're an electronics enthusiast or just curious about how it works, this DIY project is both educational and fun. **Chapter 1: Understanding the Basics of FM Transmitters** Before we dive into the circuit diagram and assembly, let's briefly explore what an FM transmitter is and how it works. 1. **What is an FM Transmitter?**    An FM transmitter is a device that c...
Read more>>

Simple led bulb driver circuit diagram

Image
LED bulb driver circuit diagram    The presented circuit is designed for the driver of the LED bulb.  This circuit is built using 3 capacitors C 1, C 2, C 3.  A list of all the components used in this circuit is given below. Components list  C1, C2 105J 400V C3 47uf 160V Resistance  R1  1M ohm Diode  1N4007 ×4 PCB board 
Read more>>

Password lock circuit diagram

Image
Building a Secure Password Lock Circuit with IC CD4017: A Step-by-Step Guide Introduction: In today's digital age, security is of utmost importance. Whether it's your home, office, or personal belongings, safeguarding them with a reliable locking mechanism is essential. One effective way to enhance security is by creating a password-protected lock circuit. In this blog post, we will guide you through the process of building a secure password lock circuit using the versatile IC CD4017. **Table of Contents:** 1. **What is IC CD4017?** 2. **Components Required** 3. **Circuit Diagram** 4. **Circuit Explanation** 5. **Construction Steps** 6. **Testing the Password Lock Circuit** 7. **Enhancements and Customizations** 8. **Conclusion** **1. What is IC CD4017?** IC CD4017, also known as the Decade ...
Read more>>

electronic components circuit symbol

Image
    Understanding Electronic Component Circuit Symbols Introduction Electronic circuits are the building blocks of modern technology. From smartphones to spacecraft, electronic circuits power and control a wide range of devices. To work with these circuits effectively, engineers and enthusiasts alike need to understand the symbols used to represent electronic components in circuit diagrams. In this blog post, we will delve into the world of electronic component circuit symbols, demystifying the key symbols you need to know.   Chart of electronics components circuit symbol  Resistors Resistors are one of the fundamental components in electronics. They limit the flow of current in a circuit. In circuit diagrams, resistors are represented by a zigzag line. The symbol is simple, resembling a serpentine path. The value of the resistance is often indicated next to the symbol in ohms (Ω). Capacitors Capacitors store electrical charge and release it when need...
Read more>>

fan regulator circuit diagram

Image
Fan regulator  The circuit presented serves as the fan's regulator. BT136 is used in this circuit. And to control the fan speed, a variable register 220k ohm has been used in this circuit. The list of electrical components used in this circuit is given below. Fan regulator circuit diagram  Electronics components list  Triac BT136  diac (DB3 C312) Resistance  R1 10k ohm V/R1 220k ohm  Capacitor  C1 104 I 400v
Read more>>

high voltage generator circuit diagram

Image
 High voltage generator circuit diagram  The presented circuit diagram is designed to generete high voltage.  This circuit generates 2000 high volts dc. This circuit should be used very carefully.  This circuit is built using transistor D882.   This circuit is used to protect crops from wild animals and to protect them from monkeys.  And this circuit is also used in mosquito bat.  A list of all the electronic components used in this circuit is given below. How to make high voltage generator circuit watch full video  Electronics components list  Transistor  Q1 D882  Capacitor  C1 105j 400v C2 102 pf C3 101 of C4 223j 2000v  Diode  all diode 1N4007  LED light Resistance  R1 1m ohm  R2 18k ohm  R3 1.5I ohm  Transformer  L1 15 turn 0.2mm copper wire  L2 30 turn 0.2mm copper wire  L3 450 turn 0.05mm copper wire  Battery 4v PC...
Read more>>

thief detector circuit diagram

Image
The presented circuit diagram is used to catch the thief.  This circuit is built using transistors BC548 and AC188.   Put a thin copper wire connected between the base and negative line of transistor BC548 where there is a way for thieves to enter the house.   Now as soon as the thief tries to enter the house, the copper wire will break and as soon as the copper wire breaks, the positive voltage through the resistance R1 10k will come to the base of transistor BC 548 and the circuit will be turned on.   As soon as the circuit is turned on, the resistance and 103PF connected between the transistor BC548 base and the collector of transistor AC188 together produce a sairan-like frequency that will be heard in the speaker connected to the collector of transistor AC188.  This circuit is very simple and very easy to use. A list of electronics components used in this circuit given below.  ...
Read more>>

gas leak detector circuit diagram

Image
LPG has become the need of everyone these days.  Nowadays everyone is using gas cylinder to cook food, but just as the use of LPG is continuously spreading its feet, similarly the accident caused by gas cylinder cannot be ignored because during use of LPG Gas leaks often lead to accidents.  A gas leak detector is a useful project to prevent accidents due to LPG leaks.   Gas Leak Detector The gas sensor MQ2 installed in the project is sensitive to Hydrogen, LPG, Smoke and Alcohol.  This project can be used to prevent any accident by detecting gas leak in home, shop and industry. The presented project serves as a gas leak detector .  This circuit is designed using gas sensor and transistor BC 148.   This circuit will notify you of gas leaks by sounding an alarm.  The list of elec...
Read more>>