This is a simple DIY metal detector circuit built using a single unijunction transistor (UJT) configured as a relaxation oscillator. It senses any metallic object brought close to its search coil. Search coil forms the inductor in timing network. When metal approaches coil then it alters the magnetic field and inductance, causing a noticeable shift […]
UJT
Unijunction Transistor (UJT) 2N2646 Datasheet
The 2N2646 is a type of Unijunction Transistor (UJT), which is commonly used in various oscillator based electronic circuit application. The following paragraphs provide the datasheet and the main specifications of the device: Pin Configuration: The following diagram shows the pinout configuration of the UJT 2N2646. General Characteristics: Electrical Specifications: Advantages and Disadvantages Common Applications […]
7 Easy Sawtooth Waveform Generator Circuits using UJT, IC 555, and Transistors
In this post I have explained how to build 7 types of easy sawtooth generator circuits, using BJTs, UJTs, and IC 555. In a sawtooth waveform the voltage increases slowly in a slanting manner or diagonally, then as soon as it reaches the peak, the waveform voltage suddenly drops to zero. Once it drops to […]
10 Simple Unijunction Transistor (UJT) Circuit Diagrams Explained
In the earlier post I have explained comprehensively about how a unijunction transistor works, in this post I will elucidate a few interesting application circuits using this amazing device called UJT. The example application circuits using UJT which are explained in the article are: 1) Square Wave Pulse Generator The first design below demonstrates a […]
Unijunction Transistor (UJT) – Comprehensive Tutorial
A unijunction transistor is a 3 terminal semiconductor device which is unlike a BJT has only a single pn junction. It is basically designed to be used as a single-stage oscillator circuit for generating pulsed signals suitable for digital-circuit applications. UJT Relaxation Oscillator Circuit The unijunction transistor could be typically wired in the form of […]