State the main difference between PUT and UJT.

State the main difference between PUT and UJT.
by

1 Answer

Answer :

Difference between PUT and UJT: (i) The intrinsic stand-off ratio of a UJT is fixed hence operating characteristics cannot be alterd. The PUT, on the other hand has operating characteristics that can be altered. These include base-base resistance, intrinsic stand-off voltage, valley current and peak current and all these can be altered by setting the values of two external resistors. (ii) The UJT is made up of a lightly doped n-region known as the base region onto which is joined a small heavily doped p-region called the emitter. The PUT on the other hand is a four layer device similar to an SCR except that the gate terminal of the PUT is connected to the n-region adjacent to the anode. (iii) PUT has high forward conductance, so it can provide high peak current pulses, even with low value capacitor in relaxation oscillator circuit. (iv) PUT has fast rise time, which allows faster rise in current and provides healthy output pulses as compared to UJT.

by

Related questions

With neat diagram explain synchronized UJT triggering circuit.

Description : With neat diagram explain synchronized UJT triggering circuit.

Last Answer : Line Synchronized UJT triggering circuit: The UJT is almost ideal as a firing device for SCRs. There are 2 main reasons for the compatibility between UJTs and SCRs. Firstly, the UJT produces a ... , the SCR is sure to have the right polarity between the anode and cathode for turning on.

Describe triggering of SCR using UJT relaxation oscillator.

Description : Describe triggering of SCR using UJT relaxation oscillator. 

Last Answer : I need it's operation

operating principle of PUT.

Description :  operating principle of PUT.

Last Answer : Constructional diagram & Operating principle of PUT:  The PUT is a PNPN device similar to SCR, but its operation is similar to the UJT. The PUT behave like a UJT whose trigger voltage VP can be set ... low resistance and VAK ≈ 1V). The PUT is also referred to as a complementary SCR (CSCR). 

Draw and explain the characteristic of UJT.

Description : Draw and explain the characteristic of UJT. 

Last Answer : UJT Characteristics: The UJT characteristic is emitter voltage versus emitter current characteristic, as shown in the figure. There three operating regions in UJT  1.Cut off region: For ... in IE will place the device into saturation and hence after valley point there is valley point. 

A UJT can........

Description : A UJT can   (A) be triggered by any one of it's three terminals (B) not be triggered (C) be triggered by two of its three terminal only (D) be triggered by all of its terminals only.

Last Answer : A UJT can be triggered by two of its three terminal only

In the emitter characteristic of UJT, the negative resistance portion.

Description : In the emitter characteristic of UJT, the negative resistance portion.  1.lies in the cut-off region 2.continues up to peak point 3.lasts until the valley point is reached 4.does not exist 

Last Answer : In the emitter characteristic of UJT, the negative resistance portion. lasts until the valley point is reached

To turn a UJT ON, the forward bias on emitter diode should be:

Description : To turn a UJT ON, the forward bias on emitter diode should be:  1. more than the peak point voltage 2. less than the peak point voltage 3. Equal to the peak point voltage 4. Equal to the stand - off voltage  

Last Answer : To turn a UJT ON, the forward bias on emitter diode should be: more than the peak point voltage 

Draw the characteristics of UJT and state its working principle.

Description : Draw the characteristics of UJT and state its working principle.

Last Answer : The characteristics of Unijunction Transistor (UJT) can be explained by three parameters: * Cutoff Region * Negative Resistance Region * Saturation Region Cutoff Region : The ... in its ON position. The emitter voltage VE remains almost constant with the increasing emitter current.

State the working principle of UJT

Description : State the working principle of UJT

Last Answer : Figure shows the equivalent circuit of a unijunction transistor with voltage source VEE connected across emitter and base 1 and VBB connected across base 1 and base 2. Hence the Emitter diode is reversed ... emitter current begins to flow ,the UJT is said to be fired, triggered or turned on.

The seven segment arrangement for numerical display on consoles, test meters and other applications can be either ________________. A. UJT or BJT B. BCD or OCD C. JFET or IGFET D. LED or LCD

Description : The seven segment arrangement for numerical display on consoles, test meters and other applications can be either ________________. A. UJT or BJT B. BCD or OCD C. JFET or IGFET D. LED or LCD

Last Answer : Answer: D

Which is the most suitable power device for high frequency ( more 100 kHz) switching application? a) Power MOSFET b) BJT c) SCR d) UJT

Description : Which is the most suitable power device for high frequency ( more 100 kHz) switching application? a) Power MOSFET b) BJT c) SCR d) UJT

Last Answer : Ans: Power MOSFET

What is the normal current path for a UJT?

Description : What is the normal current path for a UJT?

Last Answer : From base 1 to the emitter.

The sequential rise in voltage between the two bases of the UJT is called what?

Description : The sequential rise in voltage between the two bases of the UJT is called what?

Last Answer : A voltage gradient

The area between base 1 and base 2 in a UJT acts as what type of common circuit component?

Description : The area between base 1 and base 2 in a UJT acts as what type of common circuit component?

Last Answer : Variable resistor.

The UJT has how many PN junctions?

Description : The UJT has how many PN junctions?

Last Answer : One.

Draw the circuit and explain the operation of UJT relaxation oscillator.

Description : Draw the circuit and explain the operation of UJT relaxation oscillator. 

Last Answer : Working: When the supply voltage (VCC) is switched ON, the capacitor charges through resistor (R), till the capacitor voltage reaches the voltage level (VP) which is called as peak point voltage. At ... resistor R is shown as a variable resistor. The sweep period is given by the relation

A UJT exhibits negative resistance region :

Description : A UJT exhibits negative resistance region : (A) Before the break point (B) Between peak and valley point (C) After the valley point (D) Both (A) and (C)

Last Answer : A UJT exhibits negative resistance region Between peak and valley point

UJT has : -............

Description :  UJT has : -  a) two base leads b) one emitter lead c) two emitter leads and one base lead d) one emitter lead and two base leads

Last Answer :  UJT has : - one emitter lead and two base leads

A UJT has - - - PN Junction

Last Answer : A UJT has one PN Junction

What is the difference between forward and reverse bias?

Description : What is the difference between forward and reverse bias?

Last Answer : Forward bias is a PN junction bias which allows current to flow through the junction. Forward bias decreases the resistance of the depletion layer. Reverse bias is a PN junction bias that allows only ... Positive polarity on the n-type material and negative polarity to the p-type material.

Explain difference between enhancement MOSFET and depletion type MOSFET.

Description : Explain difference between enhancement MOSFET and depletion type MOSFET.

Last Answer : In enhancement MOSFET channel is not initially exists but in depletion MOSFET channel is already exists. In case of depletion MOSFET if the voltage is applied between drain and source the drain current will flow ... a channel. depletion MOSFET & enhancement MOSFET

Explain triggering of SCR using opto-coupler. State its advantages.

Description : Explain triggering of SCR using opto-coupler. State its advantages. 

Last Answer : Triggering of SCR using opto-coupler:  A simple opto-coupler based triggering circuit for SCR is shown in the figure. An optocoupler or opto-isolator is a combination of light source ... is small size and light weight device. iii)Interfacing with logic circuits is easily possible.

State the advantages of SMPS.

Description : State the advantages of SMPS.

Last Answer : Advantages of SMPS: 1. High Efficiency, more than 94%. 2. Easy maintenance and servicing. 3. High modularity and redundancy. 4. Lower power dissipation. 5. Wide AC input voltage range. 6. Less cost.

State classification of Phase controlled rectifiers.

Description : State classification of Phase controlled rectifiers.

Last Answer : Classification of phase controlled rectifiers:

State the applications of power electronics.

Description : State the applications of power electronics.

Last Answer : Power electronics applications are extended to various fields such as: 1. Aerospace, 2. Automotive electrical and electronic systems, 3. commercial, 4. industrial, 5. residential, 6. telecommunication, 7. transportation, 8. utility systems,

State the applications of MOSFET

Description : State the applications of MOSFET

Last Answer : Applications of MOSFET: i) Switching-mode-power-supplies (SMPS) and linear power supplies. ii) Brushless DC motor drives iii) Solid state DC relay iv) Automobile applications v) Stepper motor controller vi) Lighting controls vii) Solenoid drivers viii) Robotics ix) Induction heating

During forward blocking state, the SCR has:

Description : During forward blocking state, the SCR has:

Last Answer : During forward blocking state, the SCR has: low voltage, large current

Explain the on state losses in power BJT.

Description : Explain the on state losses in power BJT.

Last Answer : On state losses in power BJT: Transistor have four types of losses one is turn on state losses second is turn off state losses third is turn on switching losses and fourth is turn ... ON = VCE sat x IC With increasing collector current collector to emitter saturation voltage increases.