Dipole Antena

Dipole antenna consists of two conductors of equal length. Size can be searched by the formula as shown in the picture. The gain of this antenna is 3 dB. 72 ohm antenna impedance magnitude. The antenna is suitable for the fm transmitter and was often used by breakers on 3-meter band. How to make easy, inexpensive but the results are pretty good. please try!

RF AMFLIFIER MP3/IPOD

This is a rf amflifier schema for mp3 car or ipod :

MP3 CAR

MP3 car is an electronic device that can read files of music or songs stored in the buffer flasdisk heard through a stereo FM radio, especially used in the car. You can also include audio from a computer, tape and others. 


The voltage used is a voltage of 12-24 volts found in a car that is in turn plugs the cigarette. Operation and settings in addition to existing orders in mp3 car also can use the remote control, making it very simple use.
Radiance range is 4-5 meters with existing stereo pll.


And also good when used for broadcast in the house and if necessary strengthened by using rf amflifier radiance.


Car MP3 physical shape can see in the picture below:

MINI FM TRANSMITER

Schema C1946 Transmiter Fm

This RF Amplifier designed for FM broadcast using a single 2SC1946 VHF Power Transistor. This 10-30W RF amplifier circuit provides an appropriate power boost with an input of 1-3 watt. Tower are 30 meters high will send signal surrounding air should be around 15 km.


 

This is part list: 

All component values are drawn on the .comp and .silklayer bitmaps, with the following exception(s);
all four (4) coils (in the RF Amplifier Parts List
lowpass filter section) are: 3.5 turns, 8 mm DIA., 1.2 mm CuL closewound i.e. no wirespacing.

Note:
CuL = magnetwire, enameled copper wire, insulated (rigid) copper wire e.t.c..
2 mm equals approx. to #12 A.W.G
1 mm equals approx. to #18 A.W.G
1.2 mm equals approx. to #17 A.W.G
0.8 mm equals approx. to #20 A.W.G
0.3 mm equals approx. to #28 A.W.G.)

·                                 all diameters are measured from the inside of the coils, i.e. 'internal' diameter.

·                                 make sure to mount the rf-transistor on a appropriate heatsink and use some thermal heatsink compound between the flange of the transistor and heatsink! (Thermal resistance heatsink at least 6°C/W.)

RF Amplifier 2SC1970 88-108 MHz

5This RF power amplifier is based on the transistor 2SC1970 and 2N4427. The output power is about 1.3W and the input driving power is 30-50mW. It will still get your RF signal quit far and I advice you to use a good 50 ohm resistor as dummy load. To tune this amplifier you can either use a power meter/wattmeter, SWR unit or you can do using a RF field meter.

 

Attention :

Good grounding is very important in a RF system. I use bottom layer as Ground and I connect it with the top with wires to get a good grounding. Make sure you have some cooling at the transistor. In my case I put the 2SC1970 close to the PCB to handle the heat. With good tuning the transistor shouldn't become hot.

Transmiter IC BA1404

Whether you want to create your own radio station, transmit the music around the house, or simply create a wireless link between your iPod and a receiver in your car, this transmitter will let you do these things easily. With BA1404 HI-FI Stereo transmitter you will be able to transmit MP3 music from your iPod, computer, discman, walkman, TV / SAT receiver, and many other audio sources.

The above FM transmitter design is a result of many hours of testing and tweaking. The goal was simple; to test many existing BA1404 transmitter designs, compare their performance, identify weaknesses and come up with a new BA1404 transmitter design that improves sound quality, has very good frequency stability, maximizes transmitter's range, and is fairly simple for everyone to build. We are happy to announce that this goal and expectations have been met and even exceeded.

The transmitter can work from a single 1.5V cell battery and provide excellent crystal clear stereo sound. It can also be supplied from two 1.5V battery cells to provide the maximum range.

 

This is ic ba 1404 schema . It' good to try asembly yourself so  you know how about it. and the part another is:

Parts:

L1 - 3.5 Turns Variable Coil

BA1404 IC

38KHz Crystal

ANT - 30 cm of copper wire

Technical Specifications:

Supply Voltage: 1.5 - 3V

Dimensions: 5.7 cm x 3.5 cm x 1 cm

(W x D x H)

Parts:

L1 - 3.5 Turns Variable Coil

BA1404 IC

38KHz Crystal

ANT - 30 cm of copper wire

Technical Specifications:

Supply Voltage: 1.5 - 3V

Dimensions: 5.7 cm x 3.5 cm x 1 cm

(W x D x H)