Tuned Oscillators Pdf To Doc

Posted By admin On 22/08/21

The varicap diode in parallel with the inductor constitutes a parallel resonant network. It is tuned to the desired harmonic. Note that the reverse bias, Vbias, is fixed. The varicap multiplier is primarily used to generate microwave signals which cannot be directly produced by oscillators. Oscillators - Free download as Powerpoint Presentation (.ppt), PDF File (.pdf), Text File (.txt) or view presentation slides online.

Sometimes we need a timed signal to use as a clock (but alsofor other things).

General theory

The Barkhausen stability criterionsays that

  1. the loop gain exceeds unity at the resonant frequency
  2. the fase shift around the loop is (where )

bad enough seems that the Barkhausen Stability Criterion is simple, intuitive, and wrong.

RC&Phase Shift Oscillator

  • PDF with derivation of equation
Tuned oscillators pdf to doctor

Crystal

Quartz is a piezoelectric material. When an electricfield is placed upon it, a physical displacement occurs.Interestingly enough, we can write an equivalent electricalcircuit to represent the mechanical properties ofthe crystal.

Colpitts oscillator

  • slide with derivation formulas for the colpitts oscillator
  • Video Colpitts Crystal Oscillator Fundamentals
  • http://www.electronics-tutorials.ws/oscillator/colpitts.html
  • http://www.electronics-tutorials.ws/oscillator/crystal.html
  • https://makerf.com/posts/experimenting_with_colpitts_oscillators
  • Crystal Oscillator Design with video and web app to calculate stuffs

Negative resistance oscillator

Some active devices (like diode and transistor) have zone of negative resistance that canbe used to amplify the feedback loop of an oscillating circuit.

  • Video World's Simplest Single Transistor Oscillator - BJT with Negative Resistance
  • Page with a more elaborated explanation of NR.

Voltage controlled oscillator (VCO)

  • https://www.electronicshub.org/voltage-controlled-oscillators-vco/
  • https://electronics.stackexchange.com/questions/233607/sawtooth-vco-and-current-source-for-modular-synthesizer
  • Posts (12 e 3) about building a VCO creating a current source
  • https://electronics.stackexchange.com/questions/207668/how-do-i-make-a-vco-with-a-lm-358
  • https://www.allaboutcircuits.com/projects/diy-synth-series-vco/

Links

  • Crystal Oscillator Basics and Crystal Selection for rfPICTM and PICmicro® Devices (PDF)
  • Crystal Oscillator Circuit Design (PDF)
  • Sparkfun tutorial
  • Choosing the Right Crystal and Caps for your Design (post
  • Microcontroller Oscillator Circuit Design Considerations ((PDF)[http://www.freescale.com/files/microcontrollers/doc/app_note/AN1706.pdf])
  • Tutorial about crystals with pratical example of circuit using them.
  • Video with simple example of oscillators (with a little bit of oscilloscope)
  • Slides SIGNAL GENERATORS AND WAVEFORM-SHAPING CIRCUITS

OSCILLATORS Questions with Answers :-

1. An oscillator converts …………….

Tuned oscillators pdf to doctor
  1. c. power into d.c. power
  2. c. power into a.c. power
  3. mechanical power into a.c. power
  4. none of the above
    Answer : 2

2. In an LC transistor oscillator, the active device is ……………

  1. LC tank circuit
  2. Biasing circuit
  3. Transistor
  4. None of the above
    Answer : 3

3. In an LC circuit, when the capacitor is maximum, the inductor energy is ……….

  1. Minimum
  2. Maximum
  3. Half-way between maximum and minimum
  4. None of the above
    Answer : 1

4. In an LC oscillator, the frequency of oscillator is ……………. L or C.

  1. Proportional to square of
  2. Directly proportional to
  3. Independent of the values of
  4. Inversely proportional to square root of
    Answer : 4

5. An oscillator produces……………. oscillations

  1. Damped
  2. Undamped
  3. Modulated
  4. None of the above
    Answer : 2

6. An oscillator employs ……………… feedback

  1. Positive
  2. Negative
  3. Neither positive nor negative
  4. Data insufficient
    Answer : 1

7. An LC oscillator cannot be used to produce ………………. frequencies

  1. High
  2. Audio
  3. Very low
  4. Very high
    Answer : 3

8. Hartley oscillator is commonly used in ………………

  1. Radio receivers
  2. Radio transmitters
  3. TV receivers
  4. None of the above
    Answer : 1

Tuned Oscillators Pdf To Docx

9. In a phase shift oscillator, we use …………. RC sectionsPhysics 12mr. mackenzie's web page builder.

  1. Two
  2. Three
  3. Four
  4. None of the above
    Answer : 2

10. In a phase shift oscillator, the frequency determining elements are …………

  1. L and C
  2. R, L and C
  3. R and C
  4. None of the above
    Answer : 3

11. A Wien bridge oscillator uses ……………. feedback

  1. Only positive
  2. Only negative
  3. Both positive and negative
  4. None of the above
    Answer : 3

12. The piezoelectric effect in a crystal is ……………

  1. A voltage developed because of mechanical stress
  2. A change in resistance because of temperature
  3. A change in frequency because of temperature
  4. None of the above
    Answer : 1

13. If the crystal frequency changes with temperature, we say that crystal has …………. temperature coefficient

  1. Positive
  2. Zero
  3. Negative
  4. None of the above
    Answer : 1

14. The crystal oscillator frequency is very stable due to ………………. of the crystal

  1. Rigidity
  2. Vibrations
  3. Low Q
  4. High Q
    Answer : 4

15. The application where one would most likely find a crystal oscillator is …………….

  1. Radio receiver
  2. Radio transmitter
  3. AF sweep generator
  4. None of the above
    Answer : 2

16. An oscillator differs from an amplifier because it ………

  1. Has more gain
  2. Requires no input signal
  3. Requires no d.c. supply
  4. Always has the same input
    Answer : 2

17. One condition for oscillation is ………….

Tuned Oscillators Pdf To Doc
  1. A phase shift around the feedback loop of 180o
  2. A gain around the feedback loop of one-third
  3. A phase shift around the feedback loop of 0o
  4. A gain around the feedback loop of less than 1
    Answer : 3

18. A second condition for oscillations is ……………….

  1. A gain of 1 around the feedback loop
  2. No gain around the feedback loop
  3. The attention of the feedback circuit must be one-third
  4. The feedback circuit must be capacitive
    Answer : 1

19. In a certain oscillator Av = 50. The attention of the feedback circuit must be …………

  1. 1
  2. 01
  3. 10
  4. 02
    Answer : 4

20. For an oscillator to properly start, the gain around the feedback loop must initially be

Tuned Oscillators Pdf To Doc
  1. 1
  2. Greater than 1
  3. Less than 1
  4. Equal to attenuation of feedback circuit
    Answer : 2

21. In a Wien-bridge oscillator, if the resistances in the positive feedback circuit are decreased, the frequency……….

  1. Remains the same
  2. Decreases
  3. Increases
  4. Insufficient data
    Answer : 3

22. In Colpitt’s oscillator, feedback is obtained …………….

  1. By magnetic induction
  2. By a tickler coil
  3. From the centre of split capacitors
  4. None of the above
    Answer : 3

23. The Q of the crystal is of the order of …………

  1. 100
  2. 1000
  3. 50
  4. More than 10,000
    Answer : 4

24. Quartz crystal is most commonly used in crystal oscillators because ………….

  1. It has superior electrical properties
  2. It is easily available
  3. It is quite inexpensive
  4. None of the above
    Answer : 1

27. …………. is a fixed frequency oscillator

  1. Phase-shift oscillator
  2. Hartely-oscillator
  3. Colpitt’s oscillator
  4. Crystal oscillator
    Answer : 4

28. In an LC oscillator, if the value of L is increased four times, the frequency of oscillations is …………

  1. Increased 2 times
  2. Decreased 4 times
  3. Increased 4 times
  4. Decreased 2 times
    Answer : 4

29. An important limitation of a crystal oscillator is ……………

  1. Its low output
  2. Its high Q
  3. Less availability of quartz crystal
  4. Its high output
    Answer : 1
Tuned

30. The signal generator generally used in the laboratories is …………. oscillator

  1. Wien-bridge
  2. Hartely
  3. Crystal
  4. Phase shift
    Answer : 1

Tuned Oscillators Pdf To Doctor

OSCILLATORS Objective Type Questions and Answers pdf free download ::