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itskrish

Joined Mar 2, 2024
11
HI!
I am new to electronics .planning to do fm bug for college project

can someone explain this circuit in detail
 

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Sensacell

Joined Jun 19, 2012
3,453
These simple bugs fall into the category of "trickier than it seems"

The way the frequency is modulated is not straightforward, if fact, this produces a carrier that is both AM and FM modulated at the same time.
The audio signal voltages alter the junction capacitances in the transistor, changing both the amplitude and frequency.
 

Dinesh_2k4

Joined Aug 18, 2022
23
These simple bugs fall into the category of "trickier than it seems"

The way the frequency is modulated is not straightforward, if fact, this produces a carrier that is both AM and FM modulated at the same time.
The audio signal voltages alter the junction capacitances in the transistor, changing both the amplitude and frequency.
My main doubt here is:
just a 9V power supply and a LC tank will be able to generate a carrier , but what role does the 10pF that connects b/w Emitter and Collector play in FM modulation and signal generation?
Is it still a colpit oscillator?
 

MrChips

Joined Oct 2, 2009
30,823
My main doubt here is:
just a 9V power supply and a LC tank will be able to generate a carrier , but what role does the 10pF that connects b/w Emitter and Collector play in FM modulation and signal generation?
Is it still a colpit oscillator?
Are you the same person who started this thread?
 

Dinesh_2k4

Joined Aug 18, 2022
23
If you had already started your on thread on this subject, why did you even bother to reply here?
It gave the impression that you and the TS were the same person.
I admit but Not exactly the same person!!
I asked my friend to do it, he is a team mate of mine for this project.Im not sure if its right as im new.
but I appologise, I really thought of closing the previous thread but Dont know how to do that....
coz its dumped with a lot of simulations
 

ericgibbs

Joined Jan 29, 2010
18,869
Hi 2k4,
Whom ever you ask, you will get the same answer.

With that simple circuit, you will always have some level of amplitude modulation in addition to the FM modulation.

It will give satisfactory short range operation.
E
 

MrChips

Joined Oct 2, 2009
30,823
I admit but Not exactly the same person!!
I asked my friend to do it, he is a team mate of mine for this project.Im not sure if its right as im new.
but I appologise, I really thought of closing the previous thread but Dont know how to do that....
coz its dumped with a lot of simulations
There is no need to play games. If you need help with organizing the flow of a thread, just ask a moderator for assistance.
We prefer not to have random threads on the same subject. It makes it confusing for readers to follow. Remember, threads on AAC forums are not just for answering your own questions. Threads can be very useful for other readers who might be having similar problems.
 

MrChips

Joined Oct 2, 2009
30,823
I admit but Not exactly the same person!!
I asked my friend to do it, he is a team mate of mine for this project.Im not sure if its right as im new.
but I appologise, I really thought of closing the previous thread but Dont know how to do that....
coz its dumped with a lot of simulations
If you wish, we can close this thread and continue on the older thread.
 
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