Thermistors are fascinating components used in various electronic applications, primarily for temperature measurement and control. They come in different designs, with the two most common being the flexible and the more robust fixed versions. Essentially, a thermistor is a type of resistor whose resistance changes with temperature. There are two main types of thermistors: Negative Temperature Coefficient (NTC) and Positive Temperature Coefficient (PTC).
In general, the resistance of a metal increases as its temperature rises. This happens because the atoms in the metal start to vibrate more vigorously, making it difficult for electrons to pass through without colliding. PTC thermistors exhibit this behavior, where their resistance increases with temperature, resulting in an upward trend when graphed.
On the other hand, NTC thermistors behave differently due to their semiconductor nature. As the temperature increases, their resistance decreases, which is why they are called negative temperature coefficient thermistors. This unique behavior is linked to the atomic structure of the material used in NTC thermistors.
To understand how thermistors work, it’s helpful to consider a simplified model of a metal atom. At the center of the atom is the nucleus, surrounded by electrons in various orbital shells. Conductors typically have one to three electrons in their outermost shell, known as the valence shell. Each shell can hold a maximum number of electrons, and an electron needs a certain amount of energy to occupy each shell. Electrons farthest from the nucleus have the most energy.
For a material to conduct electricity, electrons must be able to move freely between atoms. In conductors, electrons can easily reach the conduction band and move without much restriction. However, in insulators, the valence shell is full, leaving little room for additional electrons. The nucleus holds onto these electrons tightly, and the conduction band is far away, preventing electrons from escaping and allowing electricity to flow.
Semiconductors, like those used in NTC thermistors, have a unique property. They have one too many electrons in the outer shell to act as conductors, so they behave like insulators. However, the conduction band is relatively close, and heating the material can provide electrons with enough energy to jump and break free from their atoms. As more heat is applied, more electrons gain energy, leading to a decrease in the material’s resistance.
The basic construction of a thermistor involves a piece of semiconductor material placed between two conductors, all sealed with a protective coating. This design allows the thermistor to effectively measure and respond to temperature changes.
Thermistors are essential components in many electronic devices, providing accurate temperature readings and helping to maintain optimal operating conditions. Understanding their operation and characteristics can be incredibly beneficial for anyone studying electronics or engineering.
For further learning, explore additional resources and videos on thermistors and related topics. Stay curious and keep exploring the fascinating world of electronics!
Set up a simple circuit using both NTC and PTC thermistors. Measure and record the resistance changes as you vary the temperature using a heat source. Analyze the data to understand the distinct behaviors of NTC and PTC thermistors. Discuss your findings with your peers.
Use simulation software like LTSpice or Multisim to model circuits containing NTC and PTC thermistors. Observe how the circuit responds to temperature changes. This will help you visualize the impact of thermistors in electronic circuits without physical components.
Choose an application of thermistors in real-world devices, such as thermostats or automotive sensors. Prepare a presentation explaining how thermistors are used in the device, highlighting the importance of their temperature-dependent resistance properties.
Create a project that uses a thermistor to monitor temperature changes. For example, design a simple temperature alarm system using an Arduino or Raspberry Pi. Document the design process and share your project with the class.
Engage in a group discussion about the semiconductor properties of NTC thermistors. Explore how the atomic structure and electron behavior contribute to their unique characteristics. Use diagrams and models to support your discussion.
Here’s a sanitized version of the provided YouTube transcript:
—
Thermistors come in a few variations in design, with two common types: the flexible version and the more rugged fixed version. A thermistor is essentially a thermal resistor, meaning it is an electrical resistor that changes resistance with temperature. There are two types of thermistors: the NTC (Negative Temperature Coefficient) and the PTC (Positive Temperature Coefficient).
Typically, the resistance of a metal increases as its temperature rises. This occurs because the atoms begin to vibrate, making it harder for electrons to flow through the material without colliding. The PTC thermistor behaves in a way that shows an increase in resistance with temperature, resulting in an upward trend when plotted.
In contrast, the NTC thermistor uses a semiconductor that behaves differently. We refer to it as a negative temperature coefficient because its resistance decreases as the temperature increases. This behavior is related to the atomic structure of the material.
In a simplified model of a metal atom, there is a nucleus at the center surrounded by electrons in different orbital shells. A conductor typically has one to three electrons in its outermost or valence shell. Each shell can hold a maximum number of electrons, and an electron must have a certain amount of energy to occupy each shell. The electrons farthest from the nucleus possess the most energy.
For a material to conduct electricity, electrons must be able to move between atoms. In conductors, electrons can easily reach the conduction band and move freely. However, in insulators, the outermost valence shell is full, leaving little to no room for additional electrons. The nucleus holds onto the electrons tightly, and the conduction band is far away, preventing electrons from escaping and allowing electricity to flow.
In semiconductors, there is one too many electrons in the outer shell for it to act as a conductor, so it behaves like an insulator. However, since the conduction band is relatively close, heating the material can provide electrons with enough energy to jump and break free from their atoms. As more heat is applied, more electrons gain energy, leading to a decrease in the material’s resistance.
The basic construction of a thermistor consists of a piece of semiconductor between two conductors, sealed with a protective coating.
That’s it for this video! If you want to continue your learning, check out one of the videos on screen now. I’ll catch you in the next lesson. Don’t forget to follow us on social media and visit theengineeringmindset.com.
—
This version removes any informal language and maintains a professional tone while conveying the same information.
Thermistors – Thermistors are temperature-sensitive resistors whose resistance changes significantly with temperature. – In the laboratory experiment, the thermistors were used to measure the temperature changes in the chemical reaction.
Temperature – Temperature is a measure of the average kinetic energy of the particles in a substance. – The temperature of the gas was increased to study its effect on pressure and volume according to the ideal gas law.
Resistance – Resistance is a measure of the opposition to the flow of electric current in a conductor. – The resistance of the copper wire was calculated to determine its suitability for the electrical circuit.
Electrons – Electrons are subatomic particles with a negative charge that orbit the nucleus of an atom. – The flow of electrons through a conductor constitutes an electric current.
Conductors – Conductors are materials that allow the flow of electric charge with low resistance. – Copper and aluminum are commonly used as conductors in electrical wiring due to their high conductivity.
Semiconductors – Semiconductors are materials with electrical conductivity between that of a conductor and an insulator, often used in electronic devices. – Silicon is a widely used semiconductor in the manufacturing of integrated circuits and solar cells.
Insulators – Insulators are materials that resist the flow of electric charge, used to protect or separate conductors. – The rubber coating on electrical wires acts as an insulator to prevent accidental electric shocks.
Atomic – Atomic refers to anything related to atoms, the basic units of matter and the defining structure of elements. – The atomic structure of the material was analyzed to understand its electrical properties.
Energy – Energy is the capacity to do work or produce change, existing in various forms such as kinetic, potential, thermal, and electrical. – The energy generated by the solar panels was sufficient to power the entire building.
Construction – Construction in engineering refers to the process of assembling materials to form a structure or system. – The construction of the new laboratory facility was completed ahead of schedule, allowing for advanced research in nanotechnology.
