Colpitts oscillator_Professor Marwan Mahmod

Theory of colpitts oscillator circuit

1. Ruba Sbaih
Jeelan ataree
Supervisor:
Prof: Marwan Mahmod

2. 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.

3. 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

4. Design a Colpitts oscillator using and using it
for lighting the fluorescent lamp.
Build and test design
Obtain frequency of oscillation
Output a non-distorted sine wave from self-
oscillation

5. PV

6. We tried three circuit for the colpitts oscillator:
First:

7. Second :

8. And the third one :

10. This is the output signal
By noting the # of squares
We found that the
Frequency is 9KHZ
and the output voltage
200 v

12. By installing suitably sized switched capacitors
into the circuit, the Power Factor is improved
and the value becomes nearer to 1 thus
minimising wasted energy and improving the
efficiency of a plant.

13. Thecolpittoscillatordoesnotexpensive
becauseitscircuitverysimpleandrequired
onlyasingletransistorfreeAndwhenweuse
thePVcelltosupplythepowertotheoscillator
wewillnotneedanytypeofpowersupplyto
playit.