RF Transmitter Circuits

  

The transmitting system consists of two tuned circuits such that the one containing the spark-gap is a persistent oscillator; the other, containing the aerial structure, is a free radiator maintained in oscillation by being coupled to the first. The transmitting system consists of two electrically coupled circuits, one of which, containing the air-gap, is a powerful but not persistent oscillator, being provided with a device for quenching the spark so soon as it has imparted sufficient energy to the other circuit containing the aerial structure, this second circuit then independently radiating the train of slightly damped waves at its own period.

For a fixed frequency transmitter one commonly used method is to use a resonant quartz crystal in a Crystal oscillator to fix the frequency. Where the frequency has to be variable, several options can be used.
For VHF transmitters, it is often not possible to operate the oscillator at the final output frequency.
 
In such cases, for reasons including frequency stability, it is better to multiply the frequency of the free running oscillator up to the final, required frequency. The task of many transmitters is to transmit some form of information using a radio signal (carrier wave) which has been modulated to carry the intelligence.
 
A few rare types of transmitter do not carry information: the RF generator in a microwave oven, electrosurgery, and induction heating. RF transmitters that do not carry information are required by law to operate in an ISM band. In many cases the carrier wave is mixed with another electrical signal to impose information upon it. This occurs in Amplitude modulation (AM). Amplitude Modulation: In Amplitude modulation the instantaneous change in the amplitude of the carrier Frequency with respect to the amplitude of the modulating or Base band signal.
 
 

Circuits


sponsored links


Peter's electronic projects. RF circuit diagrams. RF circuits are not easy to build. The purpose of this page is to make the circuit diagrams available for educational purposes. I won't be able to ...

The tank (LC) circuit: every FM transmitter needs an oscillator to generate the radio Frequency (RF) carrier waves. The tank (LC) circuit, the BC547 and the feedback 5pF capacitor are the oscillato...

Transmitter RF Output LED Indicator Circuit Diagram This RF output detector circuit using a visual indicator can be useful for an RF.

Have you ever wanted to broadcast your own radio station within your neighborhood? Ever get ... My Experience: FM transmitters remind me of my early years in electronics. When I was 8, I came acros...

A high quality stereo FM transmitter circuit is shown here. The circuit is based on the IC BA1404 from ROHM Semiconductors. BA1404 is a monolithic FM stereo modulator that has built in stereo modul...

simple rf receiver transmitter MICRO. Discussion in ... motor on and off. dont forget to add a free wheel diode to the dc motor so that the sparks don't burn out your electronic circuit. ... Simple...