Hartley, colpitts oscillators

Thank you verymuch madam

Rohith,

We did a short study on a similar subject,

following the lead of Dr. Puncochar..

You can find this development on my website

click on the main logo to enter the "ET" page,

then click on the page for "GC_ET_AFP-bpf".

This has the label

( Josef Punčochář )

Associate Professor VŠB-Technical University of Ostrava, · Department of Electrical Engineering 

My own developement from his idea is the second label

and this is the second link below. .

I was mostly interested in

(1) Sine Wave ( without diode control ) ( pure "Q" control )

(2) one resistor f(0) control

(3) simple magnitude_control.

Your comments are appreciated.

https://www.geocities.ws/glene77is/

http://www.geocities.ws/glene77is/GC_ET_AFP-bpf.html

Dear Glen Ellis,

Thank you very much for sharing the valuable information.

I hope your attachments will help me in my project.

Thanks,

Rohith

The oscillators can be built by a positive feedback amplifier which satisfies the Parkhausen criteria. The oscillating open loop gain AB must be equal or greater than one, which means magnitude AB=1 and the phase= 0, 2 pi,..etc. Whenever this condition is satisfied the circuit will oscillate. It remains that one has to make the circuit oscillate at certain frequency. This is normally accomplished by frequency selective circuit where the above condition is satisfied at certain specific frequency. These circuits are called timing circuits of the oscillators. It is so that the amplifier odf the oscillator is made flat which means that its gain is independent of frequency. Then the feed back network which is called the B network must be frequency selective. This means that it acts as a narrow band pass filter with the center frequency is the most preferred frequency for oscillations. This filter may be passive like an LC tuned circuit, or a phase shift network or a lag lead circuit. An alternative, one can use an active B-network, say acting also as a band pass filter.

The active filters themselves are used preferably at low frequencies where using the LC components will  make the filter bulky and lossy.

So, the active filter tuned oscillators are advantageous at low frequencies and extremely low frequencies.

Best wishes

.

Thank you professor for the detailed response.