WELCOME TO OUR PRESENTATIONOUR PRESENTATION TOPIC: TYPES OF TRANSISTOR OSCILLATORS

GROUP MEMBERSNAEIM KHAN ID: 151-19-1639MD. SAHIDUR RAHAMAN ID: 151-19-1647MD. NAHID HASAN ID: 151-19-1644MD. GOLAM RABBI ID: 151-19-1719MD. EMDADUL HAQUE ID: 151-19-1687

TYPES OF TRANSISTOR OSCILLATORS

• Tuned collector oscillator• Colpitt’s oscillator• Hartley oscillator• Phase Shift oscillator• Wien bridge oscillator

TUNED COLLECTOR OSCILLATOR

• Figure shows the circuit of tuned collector oscillator . Tuned collector oscillation is a type of transistor LC oscillator where the tuned circuit (tank) consists of a transformer and a capacitor is connected in the collector circuit of the transistor. Tuned collector oscillator is of course the simplest and the basic type of LC oscillators.

FIGURE OF COLPITT’S OSCILLATOR CIRCUIT

BACKGROUND

• An oscillator is a circuit that outputs a repetitive electronic signal i.e. a sine wave.

• The Colpitts oscillator is known for using a capacitor voltage divider as its feedback source

• Advantages include:

• Frequency stability.

•A simple and robust design.

BACKGROUND

• For oscillation to occur the Barkhausen criteria must be met.

• Loop Gain

• Phase Shift must equal zero

• Magnitude equal to unity

• Realistically the magnitude will be greater than 1

• Determine if criteria is satisfied by checking the loop gain at the frequency of oscillation

• This is the output signal

By noting the # of squares

We found that the

Frequency is 9KHZ

and the output voltage

200 v

HARTLEY OSCILLATOR

•The Hartley oscillator is an electronic oscillator circuit in which the oscillation frequency is determined by a tuned circuit consisting of capacitors and inductors, that is, an LC oscillator.

FIGURE OF HARTLEY OSCILLATOR

PHASE SHIFT OSCILLATOR

• The frequency of oscillations is given by f0=1/2piRCroot6R1=R2=R3=R C1=C2=C3=C

• Circuit Operation.

• Feedback fraction, m=Ei/Eo

• Advantage.

• Disadvantage.

FIGURE OF PHASE SHIFT OSCILLATOR

WIEN BRIDGE OSCILLATOR The wien bridge oscillator is the standard oscillator circuit for all frequencies in the range of 10Hz to about 1MHz. It is the most frequently used type of audio oscillator as the output is free from circuit fluctuations and ambient temperature. The wien bridge circuit originally developed by Max Wien in 1891 for the measurement of impedances.

CIRCUIT OPERATION

Advantage:1. It gives constant output.2. The circuit works quit easily.3. The overall gain is high because of two transistors.4. The frequency of oscillations can be easily changed by using a

potentiometer.

Disadvantage:5. The circuit requires two transistors and large number of components.6. It cannot generate very high frequencies.

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