RC shift oscillator using transistor bc547b

Discussion in 'The Projects Forum' started by leonel, Aug 31, 2010.

1. leonel Thread Starter New Member

Aug 31, 2010
9
0
hi im new in this forum and dont realy knw how it work i need help on build a shift oscillator with a bc547 i realy dont knw how to start. and the requierment are 2v(p-p) frequency 2000hz and using 9v dc
plz help me

2. Audioguru New Member

Dec 20, 2007
9,411
896
The oscillator is called a Transistor Phase-shift Oscillator.
Google has 112,000 links to schematics and parts lists. The calculation is shown for the frequency.
A few use the BC107 which was the same as a newer BC547.

3. leonel Thread Starter New Member

Aug 31, 2010
9
0
plz can u give me some glue how to start the calculation?bcz im doing the research about but im geting nothing much.

4. Wendy Moderator

Mar 24, 2008
20,766
2,536
Think 60° phase shift for each RC oscillator. The transistor input impedance should also match the other resistances.

While not what you are asking for this comes close. Just use an inverting transistor instead of a op amp.

http://en.wikipedia.org/wiki/Phase_shift_oscillator

Last edited: Sep 1, 2010
5. Audioguru New Member

Dec 20, 2007
9,411
896
Here is a link to a transistor phase-shift oscillator. It has a simple single transistor amplifier and a phase-shift network with 3 RC phase shifts. the formula is provided to calculate the values for the phase shift R and C.
http://www.electronics-tutorials.ws/oscillator/rc_oscillator.html

6. leonel Thread Starter New Member

Aug 31, 2010
9
0
thnks for ur help but my problem is i want a frequency of 2000hz and how m i gonna find the value of my Re Rc Rb in my amplifier?

7. Audioguru New Member

Dec 20, 2007
9,411
896
Re, Rc and Rb are the parts of an extremely simple single transistor amplifier.
The value of Rc is determined by how much supply current will be used and by the load resistance.
Re and the two base bias resistors are simple calculations.
The two base bias resistors in parallel and in parallel with the calculated input impedance of the transistor amplifier should be equal to the R of the RC phase shift parts.

If you cannot do these simple calculations then look in Google for a completed circuit.

8. marshallf3 Well-Known Member

Jul 26, 2010
2,358
201
Didn't your electronics course come with a required textbook?