Transmitter

[lerameur]

HI,

I have been looking at Am and FM transmitter for a little while. I
know about the theory of both, now I wanted to find one circuit of each

to see how they are different. I came across these two, but the thing
is, they look very similar. Could someone point out where is the
difference and why, thank you


link 1: http://www.electronics-lab.com/projects/rf/011/index.html


link 2: http://www.uoguelph.ca/~antoon/circ/fmt6.html


Ken

 

[Gerard Bok]

I have been looking at Am and FM transmitter for a little while. I
know about the theory of both, now I wanted to find one circuit of each

to see how they are different. I came across these two, but the thing
is, they look very similar. Could someone point out where is the
difference and why, thank you

link 1: http://www.electronics-lab.com/projects/rf/011/index.html

The output frequency is fixed here by C1 / L1
The amount of output is 'regulated' or rather squeezed by the
amplified microphone signal.
Which is: AM

link 2: http://www.uoguelph.ca/~antoon/circ/fmt6.html

Q3 forms an oscillator, together with L1, C3, C6.
The oscillator's frequency is influenced by the amplified
microphone signal. Hence: FM

Now you are going to produce a phase modulator, I guess ?

 

[Don Bruder]

The output frequency is fixed here by C1 / L1
The amount of output is 'regulated' or rather squeezed by the
amplified microphone signal.
Which is: AM


Q3 forms an oscillator, together with L1, C3, C6.
The oscillator's frequency is influenced by the amplified
microphone signal. Hence: FM

Now you are going to produce a phase modulator, I guess ?

Not a phase modulator, Pinky, A Uranium Q-38 Explosive Space Modulator!
There'll be such an Earth-shattering KABOOM, we'll finally be able to
TAKE OVER THE WORLD!

Uh... Sounds good, Brain, but how are we gonna get the fish into those
little-bitty rubber pants?

 

[Chris]

Not a phase modulator, Pinky, A Uranium Q-38 Explosive Space Modulator!
There'll be such an Earth-shattering KABOOM, we'll finally be able to
TAKE OVER THE WORLD!

Uh... Sounds good, Brain, but how are we gonna get the fish into those
little-bitty rubber pants?

--
Don Bruder - [email protected] - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... <http://www.sonic.net/~dakidd> for more info

Hi, Don. It's an Illudium Q-36 Explosive Space Modulator .

That makes me sooooo angry!

Cheers
Marvin the Martian

 

[lerameur]

The point that I did not understand is that they seemed to be
identical. The right hand side of the circuit are identical, Uses tank
oscillation, with a drive transistor. Also both is influenced by the
base of that transistor, which is the input. This is why i am confused.
They look the same for me , except for the capacitor C2 in the FM
circuit. Does this capacitor forces the amplitude to stay the same, and
make the frequency changes ?
If I look at the Am circuit, the more voltage on the base, will make
the c1 and L1 oscillation decrease in its amplitude.

k


Gerard Bok a écrit :

 

[Don Bruder]

Hi, Don. It's an Illudium Q-36 Explosive Space Modulator .

Only on Mars, ya sawed off little twerp! Down here on earth, we long ago
abandoned that primitive technology. Sheesh... Get with the times,
wouldja???

That makes me sooooo angry!

Anger-management classes will help that, I'm told... And if something
like that gets yer cute lil' iron panties in a wad, stay away from
wascally wabbits! They'll make ya blow a gasket fer sure!

 

[Homer J Simpson]

The point that I did not understand is that they seemed to be
identical. The right hand side of the circuit are identical, Uses tank
oscillation, with a drive transistor. Also both is influenced by the
base of that transistor, which is the input. This is why i am confused.
They look the same for me , except for the capacitor C2 in the FM
circuit. Does this capacitor forces the amplitude to stay the same, and
make the frequency changes ?
If I look at the Am circuit, the more voltage on the base, will make
the c1 and L1 oscillation decrease in its amplitude.

If a cheap little FM transmitter like this has some AM it doesn't matter
that much. The reverse is not true.