DIYFM发射机200mW.docx

1、DIYFM发射机200mWDIY-FM发射机200mWTX200 High Quality 200mW FM Transmitter- uses regular NPN transistors (with optional PLL module)Parts List:R1 - 47KR2 - 22KR3 - 39KR4 - 100R5 - 27KC1, C2, C4, C5, C9 - 1nC3 - 4.7uFC6 - 15pFC7 - 6.8pFC8 - 75pFC10 - 100nFC11 - 2pFC12 - 10pFC13 - 100uFQ1, Q2 - BF199L1 - 3.5 t

2、urns / 5mm dia. variable coil (65nH - 80nH).L2 - Ferrite bead 1 turn or use 1uH inductor.Technical Specifications:Supply Voltage: 9VPower Consumption: 35mARF Power: 200mWAbout TX200 - 200mW FM TransmitterHere is the latest and greatly improved TX200 VFO/VCO FM transmitter. The most versatile transmi

3、tter to date that can be turned into high fidelity stereo PLL based 200mW FM transmitter. It is a perfect circuit for transmitting your music around the house and yard. TX200 uses only two coils; one in the oscillator and the other one in the 200mW VHF amplifier so it should be fairly easy for anyon

4、e to build. It also includes built-in pre-emphasis and C5 for enhanced sound quality. While assembling the transmitter care must be taken to make sure that C1 is directly connected to L1 and C9 to L2. These caps eliminate the distortions form the DC supply and improve the sound quality greatly. 9V v

5、oltage supply is also very important because it provides the exact amount of current to Q1 to produce loud and clear sound quality. I hope that youll have as much fun as I had while building this transmitter. Enjoy! ;)Power MeterTX200 comes with built-in LED based power meter. This is a very helpful

6、 tool that will tell you if your transmitters oscillator is working properly. If RF signal is transmitted the LED will illuminate. Besides that, it will also give you a quick visual way to check how much power is being transmitted. I highly recommend that you have the transmitter and power meter on

7、the same PCB. If you like to experiment a lot, you will appreciate this inexpensive but externally helpful additionHow to use PLL to digitally tune the frequency of the TX200 transmitter?If you want to use Phase Locked Loop (PLL) to digitally tune the frequency of TX200 then you will need to make sm

8、all changes to the transmitters oscillator. Theoretically, change original variable frequency oscillator (VFO) to voltage controlled oscillator (VCO). PLL uses voltage to change the capacitance of the varicap diodes / frequency of the oscillator so two BB105 varicap diodes or any 15-30pF varicaps wi

9、ll be perfect for this.You vary the capacitance of the varicap diode(s) by applying voltage supply between 1 - 8V. If you apply 1V the capacitance will be around 34pF, and if you apply 8-30V the capacitance will be 12pF (minimum). Now, you may wonder why do we need to start from 1V? The reason is th

10、at if you apply voltages below 1V the capacitance may go as high as 200pF and we simply cant use that. 100K resistor will be used to lower the current of the voltage, because varicaps require only 0.2mA of current to operate!With this knowledge we replace C6 - 15pF capacitor with two varicaps and on

11、e resistor. That much is enough to be able to use 1 - 8V voltage to change the oscillators frequency. The second change that we will need to make is to use 2pF capacitor and connect it to the Q2 transistors collector. PLL will use this to sample the frequency and compare it with digitally selected f

12、requency. PLL will then compare those frequencies and if they are not the same PLL with vary the voltage that is applied to the varicaps, until those two frequencies are the same.Before you even connect PLL circuit to the TX200 transmitter you will need to test if the oscillator is working properly.

13、 We can tune through entire FM band (88-108MHz) by applying the voltage to the varicaps. To do so, connect PLL - Voltage Control PIN to the 10K potentiometer as shown below. With this setup you will be able to use potentiometer to change the frequency of the transmitter. If you cant go through the e

14、ntire FM band or if your frequency is out completely then you will need to change the inductance of the L1 coil.PLL ModuleThe schematic and instructions for building this PLL module can be found atpira.cz. After building it and doing some testing with it I was amazed by how well this Phase Locked Lo

15、op circuit performs. Its stable, compact, very easy to build and connecting it to TX200 transmitter was a piece of cake!Make TX200 a Stereo Transmitter!You can easily turn TX200 into a high quality stereo transmitter by connecting this stereo encoder module that you can eitherbuild it yourselforbuy

16、it as a kit. Stereo encoder kit includes all the hard to find components such as NJM2035 IC and 38KHz crystal.TX200 Prototype ImagesBA1404 HI-FI Stereo FM Transmitter - Special Edition KitBe On Air with your own radio station! BA1404 HI-FI Stereo FM Transmitter - Special Edition Kit is an exciting t

17、ransmitter that will broadcast high quality stereo signal in 88MHz - 108MHz FM band. It can be connected to any type of stereo audio source such as iPod, Computer, Laptop, CD Player, Walkman, Television, Satellite Receiver, Tape Deck or other stereo system to transmit stereo sound with excellent cla

18、rity throughout your home, office, yard or camp ground. Add500mW FM / VHF Transmitter Amplifier / Boosterfor even longer range.Special Edition BA1404 HI-FI Stereo FM Transmitter Kit includes premium components with audio grade gold capacitors, 1% Metal Film Resistors and quality PCB with Red Solder

19、Mask and Plated-Through Holes. The kit is based on the popular BA1404 stereo broadcaster IC which contains all the complex circuitry for generating the stereo FM signal. 38 KHz crystal provides a rock solid stability of sub-carrier for stereo signal.Specifications:Voltage Supply: 1.5 - 3V DC Input (

20、Single or Two AA/AAA batteries)Frequency: 88MHz - 108MHzAudio Input: StereoPCB Dimensions: 49mm x 32mm (W x H)Kit Components 1x BA1404 Stereo FM Transmitter IC 1x PCB with Red Solder Mask and Plated-Through Holes 1x 38KHz Crystal Oscillator 1x 3.5T Variable Precision RF Coil 1x 10uH Inductor 4x 10uF

21、/50V Gold Audio Capacitors 4x 1nF Ceramic Capacitors 2x 1nF Mylar Capacitors 1x 220pF Ceramic Capacitor 5x 10pF Ceramic Capacitors 2x 47K 1% Metal Film Resistors 2x 27K 1% Metal Film Resistors 1x 150K 1% Metal Film Resistor 1x 5.6K 1% Metal Film Resistor 1x 270 1% Metal Film Resistor 1x Instructions