RF oscillator

327

06:06:50

An rf oscillator mostly used in FM transmitters.

published 9 years ago

ShodanKataKana

9 years ago

This is great. I love to watch the beginning of the sine wave, it's very frantic.

faceblast

9 years ago

does the signal to be modulated get injected into this circuit, or is it mixed in later

Voltransistor

9 years ago

I been doing FM RFs with breadboards lately. It gets sensitive to different stations.

thebugger

9 years ago

Well it depends. Poor fm transmitter designs inject the signal directly into the oscillator stage while better designs use varicaps to alter the frequency. For a very good design the oscillator stage should be left alone and should be shielded from the rest of the circuit. Then you must make a buffer stage so that the other stages won't cause any disturbance in the oscillator. And then after the buffer stage a power amplifier should be put (depending on your needs). Oh and most important. Shield the whole thing up because even your presence will disturb the transmitter.

thebugger

9 years ago

Ive been making fm tranamitters lately too and even my presence disturbs the transmitter. Also with cheap poor designs you waste a lot of power transmitting harmonics. And thats really bad because you cramp the entire fm spectrum with harmonics.

Voltransistor

9 years ago

@thebugger-Thankyou! :-) You do a good job! :-) Do you also know FM receivers? They can be a pain.

thebugger

9 years ago

My advice. Just use varicaps to tune to a given frequency. It provides great frequency stability for both receivers and transmitters. But if u ask me go with AM for short range. At small radius am does not pick so much noise and the quality is good. For larger radius go with fm.

thebugger

9 years ago

Cuz both AM transmitters and receivers are easier to build and tune and dont necessarily require an inductor for the oscillator stage just an old plain wien bridge oscillator a single transistor modulator and a power amplifier stage. The long wave spectrum is at the lower end of the spectrum so no chokes and stuff are needed.

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