Draw a neat circuit of colpitt''s oscillator, Electrical Engineering

Assignment Help:

Q. Draw a neat circuit of Colpitt's oscillator using an n-p-n transistor. Give its equivalent circuit obtain expressions for (i) frequency of oscillation and(ii) minimum gain for sustained oscillations.

The Colpitt's oscillator circuit is a superb circuit and is widely used in commercial signal generators upto 100 MHz. The basic circuit of a Colpitt's oscillator is shown in fig.It basically consists of a single stage inverting amplifier and an L-C phase shift net,vork, as obvious from the circuit diagram shown. The two series capacitors C1 and C2 form the potential divider used for providing the feedback voltage-the voltage developed across capacitor C2 provides the regenerative feedback required for sustained oscillations. Parallel combination of RE and CE along with resistors Rl andR2 provides the stabilized self bias. The collector supply voltage V cc is applied to the collector through a radio.frequency choke (RFC) which permits an easy flow of direct current but at the same time it offers + Vcc very high impedance to the high frequency currents. The presence of coupling capacitor Cc in the circuit , which blocks dc but provides path for ac.

568_Draw a neat circuit of Colpitts oscillator.png

Transistor itself produces a phase shift of 180 and another phase shift of 180 is provided by the capacitive feedback. Thus a total phase shift of 360 is obtained which is an essential condition for developing oscillations. The output voltage is derived from a secondary winding L' coupled to Basic Circuit For Colpitts Oscillator. the inductance L. The frequency is determined by Fig. the tank circuit and is varied by gang-tuning the two capacitors CI and Cz. It is to be noted that capacitors C1 and Cz are ganged. As the tuning is varied, values of both capacitors vary simultaneously, the ratio of the two capacitances remaining the same.


Related Discussions:- Draw a neat circuit of colpitt''s oscillator

Usage of transistor, Usage of transistor: The bipolar junction transis...

Usage of transistor: The bipolar junction transistor that is abbreviated as BJT was the most generally used transistor in the 1960s and 70s. Even later than MOSFETs became ext

Engineer, explain the alphanumeric codes

explain the alphanumeric codes

Low and high pass filters - calculate the cutoff frequencies, At the comple...

At the completion of this unit, you will be able to determine the cutoff frequencies and attenuations of RC and RL low- and high-pass filters by using test circuits. UNIT FUNDA

Mvi move immediate instruction , MVI Move Immediate  Instruction This...

MVI Move Immediate  Instruction This form  of the instruction is used to copy 8bit  data ( specified  in the  instruction )  directly  into the  register or memory  pointed by

Electronic and electrical measurement CRO., Describe the construction and w...

Describe the construction and working of atleast two types of storage CRO

What are the drawbacks of microprocessor, There is a limitation on the size...

There is a limitation on the size of data. Most Microprocessor does not maintain floating-point operations.

What are shift registers - sequential logic circuit, What are Shift Registe...

What are Shift Registers - Sequential Logic Circuit? The Shift registers are a type of sequential logic circuit that mainly for storage of digital data and they are a group of

Compute the percentage change, Q. A particular BJT has a nominal value of α...

Q. A particular BJT has a nominal value of α 0.99. Calculate the nominal β.If α can easily change ±1%, compute the percentage changes that can occur in β.

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd