Programmable Unijunction Transistors (PUTs) are a class of highly versatile electronic components used in a variety of applications within the field of discrete semiconductors. As the name implies, these transistors are programmable, meaning that the voltage at which they switch from a high resistance to a low resistance state (also known as the trigger voltage) can be adjusted according to the needs of the specific application. The primary function of a PUT is to act as a switch that is triggered at a particular voltage, making them useful in timing circuits, oscillator circuits, and voltage or current sensing applications. Moreover, due to their unique characteristics, PUTs can also act as a relaxation oscillator, providing an electronic timing function.
In terms of their specific applications, PUTs are often used in the design of alARMs, pulse generators, and timing circuits due to their excellent ability to control the flow of electricity. One of the main characteristics of these components is their stability, which is essential for many electronic devices to function correctly. Different manufacturers produce PUTs, each offering a variety of specifications to meet diverse application requirements. Some of the notable manufacturers of Programmable Unijunction Transistors include Texas Instruments, Fairchild Semiconductor and NXP Semiconductors.