Characteristics of unijunction transistor, Electrical Engineering

Characteristics of  unijunction transistor:

Characteristics : The static emitter characteristic of UJT at a given inter base voltage VBB in shown in fig. From fig., it is noted that for emitter potentials to the left of peak point, emitter current IE never exceeds IEO. The current IEO corresponds very closely to the reverse leakage current ICO of the conventional BJT. This region, as shown in the fig., is called the cut off region. Once conduction is established at VE = VP the emitter potential VE stars decreasing with the increase in emitter current IE. This corresponds exactly with the decrease in resistance current IE. The device, therefore, has a negative resistance region which is stable enough to be used with a great deal of reliability in the areas of applications listed earlier. Eventually, the valley point reaches, and any further increase in emitter current IE places the device in the saturation region, as shown in the fig. three other important parameters for the UJT are IP, VV and IV and are defined below :

Peak Point Emitter Current IP : It is the emitter current at the peak point. It represents the minimum current that is required to trigger the device. It is inversely proportional to the inter base voltage VBB.

Valley point Voltage VV : The valley point voltage is the emitter voltage at the valley point. The valley voltage increases with the increase in inter base voltage VBB.

Valley Point Current IV : The valley point voltage is the emitter voltage at the valley point. The valley voltage increases with the increase in inter base voltage VBB.

Special Features of UJT : The special features of a UJT are :

1. A stable triggering voltage a fixed fraction of applied inters base voltage VBB.

2. A very low value of triggering current.

3. A negative resistance characteristic.

4. Low cost.

Posted Date: 2/8/2013 2:56:35 AM | Location : United States

Related Discussions:- Characteristics of unijunction transistor, Assignment Help, Ask Question on Characteristics of unijunction transistor, Get Answer, Expert's Help, Characteristics of unijunction transistor Discussions

Write discussion on Characteristics of unijunction transistor
Your posts are moderated
Related Questions
Q A wire with n = 10 30 electrons/m 3 has an area of cross section A = 1mm 2 and carries a current i = 50 mA. Compute the number of electrons that pass a given point in 1 s, and

1. Frequency Modulation theory and its explanation 2. FM transmitter schematic, tests results and measurements 3. Amplifier and Oscillator circuit explanation and calculation

Q. Describe small signal FET.What are its characteristics? Small signal FET is the FETs used for amplification. The linear characteristic of FET is used for this purpose The in

Q. DC Motor Characteristics? We gain an understanding of the speed-torque characteristics of a dc motor from Equations. In shunt motors, the field current can be simply control

how the clipper circuits are working? explanation of working of clipper circuits

Q. A60-Hz, three-phase transmission line has a total per-phase series impedance of 35+j140 .Ifit delivers 40 MW at 220 kV and 0.9 power factor lagging, find: (a) The voltage, c

Simulation of a pn Junction An n + p junction is fabricated on a p-type silicon substrate with N A = 8×10 15 cm -3 . The n+ region has a concentration of N D = 1.5×10 18

Considering Figure, let balanced positive-sequence, three-phase voltages with ¯V AB = 100√3 0° V (rms) be applied to terminals A, B, and C. The three-phase wye-connected balanced

Improving Joints and Connections - Energy Loss Improper joints are a source of energy loss in both overhead and underground systems. The conductivity of joint should not be le

First Quadrant or Class A chopper A chopper  two mode operation of class  A chopper  can be explained as follow.