DIY-FM发射机200mW

TX200 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 turns / 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 transmitter 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 anyone 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 voltage 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 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 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 small 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 will 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 that 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 one 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 frequency. 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. 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 entire 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 Loop 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 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 transmitter 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 clarity 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 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 S