oscillator selecting and finding problem in my circuit

[rakirajueee08]

I am a undergrad student.I have a problem with a oscillator circuit.I have found a oscillator circuit from net and using it as a oscillator in my circuit.But my problem is that i could not find that what type of oscillator it is and what is it's operation?It would be helpful for me if someone please help me to know the type and operation of the oscillator .Thank you.I have given the figure attached.

 

[godfreyl]

It's a Hartley oscillator.

In future please try to make your pictures smaller. That one you posted is 3.5MB. The one below is only 42K and it still looks OK, IMHO.

 

[rakirajueee08]

Thanks a lot and sorry for the inconvenience with the size of the figure.I have a confusion about how the transistor performing the switching purpose and giving the oscillation?

It's a Hartley oscillator.

In future please try to make your pictures smaller. That one you posted is 3.5MB. The one below is only 42K and it still looks OK, IMHO.

 

[LvW]

Thanks a lot and sorry for the inconvenience with the size of the figure.I have a confusion about how the transistor performing the switching purpose and giving the oscillation?

....switching purpose? Please do not think only of switching operations of a transistor. Such a transistor can be - and is (!) - used as a linear amplifier. And that is the task of the transistor in this circuit.

Question: Do you know the general oscillation condition (Barkhausen?). Otherwise you cannot understand why a circuit with feedback can oscillate - under certain conditions.
In short: There must be an amplifier and a feedback loop with a phase shift of 360 deg for one single frequency. This can be accomplished using a transistor with a filter in the feedback loop.
There are several alternatives to do this.
One of these is the HARTLEY principle: As you know there is a phase shift of 180 deg between base and collector.
The remaining 180 deg (at one single frequency) are caused by a 3rd-order high-pass filter consisting of two inductances and one capacitor.
Please note that
* this filter is fed by a current source (transistor), and
* the 12 V supply provides a signal ground.

Thus you have a classical L-C-L high pass PI-filter in the feedback loop.

 

[rakirajueee08]

sir as you have said that it is a hartley oscillator,I could not find any hartley oscillator like this in the internet and in my book ?so I am unable to understand the operation ?can you please tell me the operation in more detail?Thank you a lot.

 

[rusty81]

First of all, you must understand what is a positive feedback, a filter, and an amplifier

**broken link removed**

 

[LvW]

sir as you have said that it is a hartley oscillator,I could not find any hartley oscillator like this in the internet and in my book ?so I am unable to understand the operation ?can you please tell me the operation in more detail?Thank you a lot.

In my post#4 I have asked you if you know the oscillation condition. What is your answer?
Otherwise, you cannot understand the circuits operation.