We know they've apparently cut your country off from Google but can you get to Wikipedia?

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

 

We know they've apparently cut your country off from Google ...

Not that I can tell. Why would Google be blocked in India?

 

Here is my schematic of phase shift oscillator, i want to know how to choose what should be the voltage across base of transistor and other such parameter as capacitor, pls pls tell me what is the procedure for this will designing ckt...!

 

Choosing the transistor bias voltage is a simple function of picking a voltage that is greater than the EB voltage drop. This will make the transistor 'turn on'. If you are inputing a sine wave to the base then the bias voltage you select should reflect whether you want the transistor 'on' for the entire 360 degree sine wave, or just a portion of it.

 

R7 in your oscillator is supposed to connect to the collector of the transistor.

Your oscillator circuit has nothing to limit its output amplitude so it will be clipped with bad distortion.

 

If you are inputing a sine wave to the base then the bias voltage you select should reflect whether you want the transistor 'on' for the entire 360 degree sine wave, or just a portion of it.

now, i am understanding how to select voltage but have doubt in turning on transistor for some portion, pls sir, give some example of it for better understanding..!

 

When the base voltage rises .7 volts above the emitter voltage(ground) then the transistor conducts and the voltage at the collector goes down to very near emitter level. As soon as the voltage goes below .7 volts the transistor turns off and the voltage at the collector rises to the supply rail level.

 

Since you do not know how to properly bias a simple transistor circuit then look in Google for a phase-shift oscillator circuit. I looked and found a site with a schematic, a parts list and an oscilloscope photo of its waveform. Here is the site:
http://www.visionics.ee/curriculum/...ft Oscillator/RC Phase Shift Oscillator1.html

 

Thank you member you are helping me lot.!!

 

Since you do not know how to properly bias a simple transistor circuit then look in Google for a phase-shift oscillator circuit. I looked and found a site with a schematic, a parts list and an oscilloscope photo of its waveform. Here is the site:
http://www.visionics.ee/curriculum/Experiments/RC%20Phase%20Shift%20Oscillator/RC%20Phase%20Shift%20Oscillator1.html

the link is showing this images!!
what does it mean??

 

I'm hypnotized.

 

still having some question about, calculating the value of resistance in potential divider bias.
as how to find value of resistance pls give some more example of it.

 

the link is showing this images!!
what does it mean??

I don't know what the squares are for but did you scroll and see the parts list, schematic and 'scope waveforms?

 

still having some question about, calculating the value of resistance in potential divider bias.
as how to find value of resistance pls give some more example of it.

If you go to school and learn about transistors or read about them on the internet then you will see that the potential divider that makes the base bias should have a current that is 10 times to 20 times the base current. This circuit has the current in the potential divider about 14.5 times the base current.

 

still having some question about, calculating the value of resistance in potential divider bias.
as how to find value of resistance pls give some more example of it.

I once used 4.7K resistors because that was all I had. I would have prefered to use 10K resistors so the overall current use would be lower, but, guess what?, BOTH of them worked just fine.



Lots of hobby designers pick a value because "It is what they have on hand"

Stop obsessing over EXACT value and build something would you. Experiment and "see what happens when..."

Get busy on the project and quite hanging out here asking questions- do the experiment and see what happens. Look at the meter readings change. Learn by doing. Often times the most educational experience you have will be a monumental failure. Those moments truly teach.

 

The current in the potential divider that biases a transistor should be 10 times to 20 times the base current because then a low gain transistor, a medium gain transistor and a high gain transistor will all work almost the same. When you buy a transistor you don't know its current gain.

If the resistor values in the potential divider are lower than 10 times the required value then the input impedance is too low and the value of the input capacitor must be increased to pass low frequencies. So you should not simply use whatever values you have.

 

I seen in Robert L. Boylestad (elect. book), it give a relation (beta)*Re>= 10*R2 (Testing Condition) what does it mean??

 

I seen in Robert L. Boylestad (elect. book), it give a relation (beta)*Re>= 10*R2 (Testing Condition) what does it mean??

You forgot to post the schematic that shows R2.
R2 might be the resistor to ground in the potential divider that biases the base of a common-emitter transistor.
Beta is the current-gain of a transistor. Re is its emitter resistor.
The book says that beta times Re should be more than ten times R2.
Similar to saying that the current in the potential divider should be 10 times to 20 times the base current.

 

Similar to saying that the current in the potential divider should be 10 times to 20 times the base current.

What does this mean??
pls give example.

 

What does this mean??
pls give example.

You need a better translation program. "The current in the potential divider should be 10 times to 20 times (more than) the base current (of the transistor)".
I said it in perfect English.

Didn't you see the phase-shift oscillator project that I posted? Didn't you calculate its voltages and currents?