Please , see the figure below . Can I substitute the LC tank in this circuit with a crystal ( no crystal oscillator, just the xtal) ??. If so , do I have to add a capacitor in series with xtal or what changes do I have to do ?.

 

No, you cannot replace LC circuit with a crystal. The properties of a crystal and LC circuit are very different.

If you want a crystal controlled oscillator, you need a circuit designed for a crystal.

 

No, you cannot replace LC circuit with a crystal. The properties of a crystal and LC circuit are very different.

If you want a crystal controlled oscillator, you need a circuit designed for a crystal.

Thanks a lot sir.

 

Here is an example of a crystal oscillator circuit.

 

Here is what the equivalent circuit of a crystal looks like. It is a bit more complicated than and LC tank.

 

Here is an example of a crystal oscillator circuit.

View attachment 285456

What a coincidence, I did that one two days ago with a 4 mHz xtal and it worked as prescribed, however I don't know how to connect an audio source. I think I should put a coupling capacitor at the output of this oscillator and connected to base base of another npn with positive of the audio source to the collector and the transmitter to the ground of it .. Is that right ?.

 

It think, what you had in mind was a mixer. The frequencies could be anything, including an audio source.

 

It think, what you had in mind was a mixer. The frequencies could be anything, including an audio source.
View attachment 285473

Oh that looks good , I will try it. Thanks a lot.

 

AM band Transmitter (techlib.com)

Also on that web page is:

It might do for some uses.