Quick question for u guys .. plz have a look

S

Student Forever

New Member

• Mar 6, 2009

• #1

Hi guys.

tell me what u know about this question plz.



Explain how the AFC voltage is derived and used to control the Local oscillator.

 

blueroomelectronics

Well-Known Member

• Mar 6, 2009

• #2

Have you tried Google?

 

S

Student Forever

New Member

• Mar 6, 2009

• #3

yep.. but it confusing me

 

S

Speakerguy

Active Member

• Mar 6, 2009

• #4

D O Y O U R O W N H O M E W O R K

 

Last edited: Mar 6, 2009

S

Student Forever

New Member

• Mar 6, 2009

• #5

thanx for ur advise speakerguy79

 

Last edited: Mar 6, 2009

crutschow

Well-Known Member

Most Helpful Member

• Mar 6, 2009

• #6

If you gave us some idea that you had actually thought about the answer to the question, perhaps we would be more likely to help.

 

blueroomelectronics

Well-Known Member

• Mar 6, 2009

• #7

What part is confusing you?

 

S

Student Forever

New Member

• Mar 6, 2009

• #8

I mean when i found an automatic frequency control threat , it doesn't talk about the oscillator or my subject.

 

C

colin55

Well-Known Member

• Mar 6, 2009

• #9

What was the threat?

Do you realise WARS have been started over a simple spelling mistake.

 

K

kchriste

New Member

Forum Supporter

• Mar 6, 2009

• #10

Think about this:
How does the discriminator in an FM demodulator work? What happens on the output of the discriminator when the received station is off ±frequency?

 

audioguru

Well-Known Member

Most Helpful Member

• Mar 6, 2009

• #11

The FM detector produces a DC voltage when the radio is tuned away from the center of the station. The DC voltage corrects the frequency of the voltage-controlled local oscillator.

It is that simple.
Cheap FM radios drift their tuning so they use AFC to correct it. Good FM radios do not drift and do not need AFC.

 

S

Student Forever

New Member

• Mar 7, 2009

• #12

thanx alot audioguru

 

Q

q5101997

New Member

• Mar 7, 2009

• #13

What does AFC stand for?

 

audioguru

Well-Known Member

Most Helpful Member

• Mar 7, 2009

• #14

q5101997 said:

What does AFC stand for?

Click to expand...

Automatic-Frequency-Control.
When you tune toward a station then the AFC circuit snaps the tuning toward the center of the station's frequency. When you tune away then it seems like the station's frequency is very wide then it snaps away.

Manufacturers of cheap radios use AFC because the frequency of the cheap radios drifts. They blame the drifting on the stations. But stations are crystal controlled and do not drift.

 

Q

q5101997

New Member

• Mar 7, 2009

• #15

Thanks Donald