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:
link 2:
Ken
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?
Hi, Don. It's an Illudium Q-36 Explosive Space Modulator .
That makes me sooooo angry! :-)
Cheers Marvin the Martian
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.
kGerard Bok a =E9crit :
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???
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! :)
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.
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