Ujt uni junction transistor - basics
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Original Uni-junction transistor or UJT is a simple device in which a bar of N-type semiconductor material into which P-type material is diffused; somewhere along its length defining the device parameter as intrinsic standoff. The 2N2646 is the most commonly used version of UJT.
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Solution
Out of all the methods listed above PE ratio is the best indicator for almost all the sectors (apart
from banking sector), the reason being that PE ratio being a valuation model which takes into
consideration the earnings as well as the current market price. Having MPS makes it relevant
from an equity investing standd point.
However in certain sectors like banking sector, the size of book assets determine the value of the
company and not the earnings, hence in such situations we should consider Book value to Market
cap ratio for inter company comparison.
Incase of financially leveraged company, where the entire sector is high financial leverage, EV /
EBITA can be used to compare two companies.
Also, it is highly advisable to not to look at a ratio in isolation, but to take a holistic approach in
investment decisions..
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This article discusses different power electronics devices that are in use like power diodes, power thyristors, power transistors, IGBT, GTO, IGCT and others. This article will give a basic view of these devices and their operations.
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The document discusses unijunction transistors (UJTs) and programmable unijunction transistors (PUTs). It describes their equivalent circuit models, characteristics such as intrinsic standoff ratio and peak voltage, and applications in relaxation oscillators and timing circuits. Examples are provided to illustrate how to calculate values like standoff voltage from given specifications. PUTs offer the advantage over UJTs of having programmable parameters set by external resistors.
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This document outlines the syllabus for a Power Electronics course. It covers key topics like power semiconductor switches, AC-DC converters, DC-DC converters, AC-DC inverters, and AC-AC converters. Specific units will discuss power switching devices, phase controlled rectifiers, choppers/SMPS, inverters, and voltage regulators. The course aims to develop skills for designing power converters for drive and power system applications and to understand commercial and industrial power electronics applications.
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Ujt uni junction transistor - basics
- 1. UNI JUNCTION TRANSISTOR (UJT) Basicsof Electronics PREPARED BY ATHEENA PANDIAN
- 2. TOPICSFOR DISCUSSION Presentation Outline What is UJT Symbol Construction Working Characteristics Applications 1. 2. 3. 4. 5. 6.
- 3. What is UJT? A unijunction transistor is a three-lead electronic semiconductor device with only one junction that acts exclusively as an electrically controlled switch. BSI|2020BrandGuidelines
- 4. BasicsofElectronics The most common application of a unijunction transistor is as a triggering device for SCR's and Triacs but other UJT applications include sawtoothed generators, simple oscillators, phase control, and timing circuits. WHY UJT?
- 5. The symbol of UJT is designed in such a way that arrow is bent and shown that it is in the direction towards the channel. Symbol of UJT
- 6. BSI|2020BrandGuidelines Construction of UJT In Unijunction Transistor, the PN Junction is formed by lightly doped N type silicon bar with heavily doped P type material on one side. The ohmic contact on either ends of the silicon bar is termed as Base 1 (B1) and Base 2 (B2) and P-type terminal is named as emitter.
- 7. WorkingofUJT The simplified equivalent circuit (at Figure) shows that N-type channel consists of two resistors RB2 and RB1 in series with an equivalent diode 'D' representing the PN junction. The emitter PN junction is fixed along the ohmic channel during its manufacturing process. 1. 2. 3.
- 8. WorkingofUJT 4. The variable resistance RB1 is provided between the terminals Emitter (E) and Base 1 (B1), the RB2 between the terminals Emitter (E) and Base 2 (B2). Since the PN junction is more close to B2, the value of RB2 will be less than the variable resistance RB1.
- 9. WorkingofUJT The voltage across resistance RB1 of the voltage divider circuit is calculated by
- 11. CUTOFF Cutoff region is the area where the Unijunction Transistor (UJT) doesn’t get sufficient voltage to turn on. The applied voltage hasn’t reached the triggering voltage, thus making transistor to be in off state. NEGATIVE RESISTANCE REGION When the transistor reaches the triggering voltage, VTRIG, Unijunction Transistor (UJT) will turn on. After a certain time, if the applied voltage increases to the emitter lead, it will reach out at VPEAK. The voltage drops from VPEAK to Valley Point even though the current increases (negative resistance). SATURATION Saturation region is the area where the current and voltage raises, if the applied voltage to emitter terminal increases.
- 12. Applications of UJT Switching Device Triggering Device for Triacs and SCR’s Timing Circuits For phase control In saw tooth generators In simple relaxation oscillators 1. 2. 3. 4. 5. 6.
- 13. Thank You