Thermistor circuit

While the change in resistance due to heat is generally undesirable in standard resistors, this effect can be put to good use in many temperature detection circuits. Thus being non-linear variable-resistance devices, thermistors are commonly used as temperature sensors having many applications to measure the . Aug If this were not the case, resistors would make weird things happen in circuits , such as an LED that gets much brighter and dimmer as the ambient temperature changes. This is where the thermistor comes in.

This application note focuses on circuit solutions that use Negative Temperature Coefficient (NTC) ther - mistors in the design. The Thermistor has a non-linear.

Jul Finally, of course, we want to have the temperature reading, not just a resistance! To use an NTC thermistor in a detection circuit , put a small voltage across the thermistor. The resistance of the thermistor will reflect the temperature, with its resistance dropping rapidly as temperature increases.

If the user can measure the resistance electrically, solving for the temperature is easy with the resistance versus temperature curve that Ametherm provides for a specified NTC thermistor. However, if the thermistor is embedded in a circuit , the resistance changes are recorded in terms of the corresponding voltage or current. When selecting a sensor, some key . In this application the thermistor is used to protect a circuit by limiting the amount of current that can flow into it.

If too much current starts to flow into a circuit through the thermistor this causes the thermistor to warm up.

With the bridge being balance any change in temperature will cause a resistance change in the thermistor and a significant current will flow through the ammeter. It is also possible to use a vari- able resistor Rand to derive the temperature from its resistance value (in balanced condition). An example of a circuit including . Abstract: This article describes a simple and cost effective method of measuring temperature using a. An interchangeable- thermistor temperature-measurement application is described and a basic framework circuit which can be modified to use alternative components is provided.

When a potentiometer is used instead of a thermistor , the application can also be used to measure other process variables. Take the reciprocal of the result to get the temperature in Kelvin. Some of the most common uses of thermistors are in digital thermometers, in cars to measure oil and coolant temperatures, and in household appliances such as ovens and refrigerators, but they are also found in almost any application that requires heating or cooling protection circuits for safe operation. Apr This two-part article describes how to use a simple voltage divider circuit with a thermistor to achieve high-accuracy temperature readings over broad measurement ranges.

Part one discusses the circuit and various temperature estimation methods. This simple temperature relay circuit can be used to signal a fire or setpoint for temperature monitoring function. High Temperature Alarm Circuit. The high temperature alarm will beep and LED blinks when the temperature of the device increases abnormally. Thermistors are simple, inexpensive, and accurate components that make it easy to get temperature data for your projects.

Remote weather stations, home automation systems, and equipment control and protection circuits are some applications where thermistors would be ideal. With NTC thermistors , resistance decreases as temperature rises. An NTC is commonly used as a temperature sensor, or in series with a circuit as an inrush current limiter. PTC thermistors are commonly installed in series with a circuit , and used to protect .