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
Draw the re-model for the circuit given in figure and calculate: a). The input impedance (β=100), b). The output impedance (r0 = 50 kΩ) and c). The mid-band collector-base

20 cells with emf 1.45V and internal resistance 0.5Ω for each cells is linked 4 rows which every rows having of 5 cells in series. Load resistance 15Ω is connected to the battery.

Q. Explain about Address Structure? Address Structure: ISDN address structure is illustrated in figure. ISDN number part has a maximum of 15 digits and ISDN sub address part

Mode 1 ( 0 By  applying a positive  output  pulse  of the pulse  width modulator to  the  transistor Q 1 it gets turned on.  An input  current  in flows  through V in   Q 1

Q. Illustrate the basic use of binary in IT ? The binary system is thus useful in IT because not only any number, but any information, can be represented in terms of only 0s an

GTO ( Gate Turn Off) GTO stands for gate  turn off  thyristor . it is four layer  PNPN  device. It can be  triggered into conduction like a conventional thyristor  by a pulse


Q. Explain different Routing plan adopted in a Telephone network.  Ans: Hierarchical networks are capable of handling heavy traffic where required, and at the same time us

For large number of measurements the mean is calculated by taking a sample. Each sample that is taken has a mean. The mean of various sample difference from sample and are known to

1. The circuit below will be most efficiently analyzed by obtaining the Thevenin equivalent circuit for the circuit to the left of the points (a-b) on the schematic. The capacitor