Radio Transmitter and Its component description

TRANSMITTER:

In electronics and telecommunications a transmitter or radio transmitter is an electronic device which, with the aid of an antenna, produces radio waves.

Pre-knowledge:

Before actually learning going for transmitter we should have a clear idea about radio waves.These waves are actually responsible for the transmission of our desired signals.

RADIO WAVES:

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Radio waves have frequencies from 300 GHz to as low as 3 kHz, and corresponding wavelengths from 1 millimeter to 100 kilometers^.Like all other electromagnetic waves, they travel at the speed of light. Naturally occurring radio waves are made bylightning, or by astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, satellite communication, computer networks and innumerable other application.

DETAIL STUDY OF A TRANSMITTER:

BASIC COMPONENTS:

a. Oscillator

b. Antenna

c. Power supply

DESCRIPTION OF COMPONENTS:

OSCILLATOR:

modern electronic communication system have many applications that require stable, repetitive,  wave forms to oscillate or to fluctuate between two state or conditions. An oscillator is a device that produces  oscillations(i,e. generate wave forms), in transmitters, oscillator is a device that produces electrical oscillations.

ANTENNA:

A transmitting antenna takes waves that are generated by electrical signals inside a device such as a radio and converts them to waves that travel in an open space. The waves that are generated by the electrical signals inside radios and other devices are known as guided waves, since they travel through transmission lines such as wires or cables. The waves that travel in an open space are usually referred to as free-space waves, since they travel through the air or outer space without the need for a transmission line. A receiving antenna takes free-space waves and converts them to guided waves.

                                                                            

It is a metallic conductor system capable of radiating and capturing electromagnetic energy. Antennas are used to interface transmission lines to the atmosphere , the atmosphere to transmission lined or both . For an antenna to efficiently receive radio signals,It must abstract energy from the radio wave as it passes by the receiving point. Electromagnetic  wave reception occurs in an antenna bocz electromagnetic  flux of the wave cuts across the antenna conductor, including a voltage into the conductor that varies with the time in exactly the same as the current  flowing in the antenna that radiated the wave, the induced voltage along with the current it produces represents energy that the antenna absorbs from the passing wave.

POWER SUPPLY:

A SIMPLE BATTERY WOULD MEET OUR LEARNING PURPOSE.

LET’S  LEARN THE BASIC CONSTRUCTION OF A TRANSMITTER.

AS WE HAVE LEARNT IN ABOVE SECTION IN THEORITICAL WAY,

SO LETS MOVE TO PRACTICAL AND WILL HAVE FUN.

BASIC COMPONENTS:

1.OSCILLATOR.

2.HEAD PHONE JACK.

3.ANTENNA(OR SIMPLE CONDUCTIING WIRE DEPENDS ON U).

4.CIRCUIT BOARD OR A SIMPLE BREADBOARD.

5.AUDIO TRANSFORMER.

6.POWER SUPPLY.

 CONSTRUCTION:

1.The crystal should have a  black dot on it.WHICH WILL BE SHOWN IN THE FIGURE This is the only pin that we will not use on the crystal. Next is audio transformer . In this circuit it is used as a modulator.

2.This transformer has two leads on the one side and three on other side.the two lead side is used for low impedence application,three lead side is used for high impedence operation,

3.To Have a better range we generally connect the low impedence side of the transformer to the oscillator

4. The modulator changes the strength of the radio waves to match the loudness of the music or voice we want to transmit.

5. Connect head phone jack as shown in the figure,  We will connect the red wire of the headphone jack to the pin above the black dot. The white wire can also connect here if it is a stereo jack. We will connect the black wire or the ground to the pin to the right of the dot.

6. Connect the last pin to an antenna.

7.Connect the battery as shown in figure.

8.Circuit is ready.

Circuit diagram.

Operation:

The power supply 9v moves to 9v and 0v at a variation of say 1million times for a 1000000mhz oscillator.Here telephone jack can also be used in place of a headphone jack and speaking directly through telephone handset,when this applied to the antenna it generates a radio waves and will be transmitted.

           Now take ur radio.tune it frequency(If you used a 1.0000MHz crystal then you will tune your radio to 1000for 1.2000MHz crystal will give you 1200 on the radio,(on radio they are in khz).