Rangkaian FM-VHF Amplifier Booster Transmitter

Rangkaian FM-VHF Amplifier Booster Transmitter

This is a high performance low noise 500mW amplifier / booster for all low power FM transmitters such as BA1404, BH1417, BH1415, 433MHz transmitter modules, etc. The amplifier chip is an integrated circuit containing multiple transistor stages and all other parts conveniently within a single small package. Boosting your FM transmitter has never been easier and the output signal can also directly drive 2n4427 or 2n3886 transistors for 1W or 5W of RF output power.

Specifications
Output Power: 500mW
Input Frequency: 50MHz - 1300MHz
Voltage Supply: 9-12V

Component List
1x High Performance FM / VHF Amplifier Chip
1x 10uH Choke
1x 220 Ohm
3x 1nF Ceramic Capacitor
1x Instructions and Schematic

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Rangkaian Transmitter FM 15 W

15W Fm-transmitter

Building a good fm-transmitter(88-110Mhz) begins with getting a good schematic. You don't have to understand the precise working of the transmitter to build it. But some basic information won't harm. A transmitter alone is, as you probably know, is not enough to start your radio-station. In the simplest form you need 4 things. First an input device such as an amplifiler you also use with your home-stereo.
You can also use a walkman. Details about input-devices in the page: "Input". Second you need a regulated power-supply. In this case a 14-18 Volts/2,5-3,5 Ampere. One of the most influencial things you need is antenna and coax-cable. More about this later on. And finally the transmitter itself. You can devide the transmitter in two main parts: the oscillator and the amplifier. The oscilator converts electric sound information into electromagnetic waves. The amplifier gives these waves
a bigger amplitude.

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Simple FM Transmitter Circuit Diagram

Simple FM transmitter with a single transistor

Mini FM transmitters take place as one of the standard circuit types in an amateur electronics fan's beginning steps. When done right, they provide very clear wireless sound transmission through an ordinary FM radio over a remarkable distance. I've seen lots of designs through the years, some of them were so simple, some of them were powerful, some of them were hard to build etc.

Here is the last step of this evolution, the most stable, smallest, problemless, and energy saving champion of this race. Circuit given below will serve as a durable and versatile FM transmitter till you break or crush it's PCB. Frequency is determined by a parallel L-C resonance circuit and shifts very slow as battery drains out.

Schematic
Simple FM Transmitter involves on a single transistor oscillator

Technical datas:

Supply voltage : 1.1 - 3 Volts
Power consumption : 1.8 mA at 1.5 Volts
Range : 30 meters max. at 1.5 Volts

Main advantage of this circuit is that power supply is a 1.5Volts cell (any size) which makes it possible to fix PCB and the battery into very tight places. Transmitter even runs with standard NiCd rechargeable cells, for example a 750mAh AA size battery runs it about 500 hours (while it drags 1.4mA at 1.24V) which equals to 20 days. This way circuit especially valuable in amateur spy operations :)

Transistor is not a critical part of the circuit, but selecting a high frequency / low noise one contributes the sound quality and range of the transmitter. PN2222A, 2N2222A, BFxxx series, BC109B, C, and even well known BC238 runs perfect. Key to a well functioning, low consumption circuit is to use a high hFE / low Ceb (internal junction capacity) transistor.

Not all of the condenser microphones are the same in electrical characteristics, so after operating the circuit, use a 10K variable resistance instead of the 5.6K, which supplies current to the internal amplifier of microphone, and adjust it to an optimum point where sound is best in amplitude and quality. Then note the value of the variable resistor and replace it with a fixed one.

The critical part is the inductance L which should be handmade. Get an enameled copper wire of 0.5mm (AWG24) and round two loose loops having a diameter of 4-5mm. Wire size may vary as well. Rest of the work is much dependent on your level of knowledge and experience on inductances: Have an FM radio near the circuit and set frequency where is no reception. Apply power to the circuit and put a iron rod into the inductance loops to chance it's value. When you find the right point, adjust inductance's looseness and, if required, number of turns. Once it's OK, you may use trimmer capacitor to make further frequency adjustments. You may get help of a experienced person on this point. Do not forget to fix inductance by pouring some glue onto it against external forces. If the reception on the radio lost in a few meters range, than it's probably caused by a wrong coil adjustment and you are in fact listening to a harmonic of the transmitter instead of the center frequency. Place radio far away from the circuit and re-adjust. An oscilloscope would make it easier, if you know how to use it in this case. Unfortunately I don't have any :(

Every part should fit on the following PCB easily. Pay attention to the transistor's leads which should be connected right. Also try to connect trimmer capacitor's moving part to the + side, which may help unwanted frequency shift while adjusting. PCB drawing should be printed at 300DPI, here is a TIFF file already set.

The one below is a past PCB work of mine, which was prepared to fit into a pocket flashlight. Since it was so crowded, use the new computerized PCB artwork instead, yet very small. Take a look at my PCB design page to get information on my work style.

Here is a completed and perfectly running circuit, mounted in a pocket light, taking the advantage of the 1.5V AA cell slot near it. Microphone is fixed into the bulb's place and antenna is made out of a 30cm soft cable. When cover is placed, it becomes very handy!

Do not forget, restrictions on radio frequency transmitting devices may differ in your local area. This circuit has a power output that should be less than 1mW so have to be safe under many kinds of legal conditions but particular attempts such as listening to other people's private life will always be disapproved everywhere.

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Single Chip FM Transmitter

Skema Rangkaian Single Chip FM Transmitter

A simple FM transmitter links your home-entertainment system to a portable radio that can be carried around the house and into the back yard. For example, you can play music on the CD changer in your living room, and listen to it on a portable radio by the back-yard barbeque.

IC1 is a voltage-controlled oscillator with integrated varactor. Its nominal frequency of oscillation is set by inductor L1, and a 390nH value places that frequency at 100MHz. Potentiometer R1 then lets you select a channel by tuning over the FM band of 88MHz to 108MHz. Output power is about -21dBm into 50 (most countries accept emissions below 10dBm in the FM band).

The home system's left and right audio signals are summed by R3 and R4, and attenuated by the (optional) potentiometer R2. R2's wiper signal serves as a volume control by modulating the RF frequency. Signals above 60mV introduce distortion, so the pot attenuates down from that level.

In the absence of a standard FM radio antenna, 75cm (30 inches) of wire will suffice as a transmitting antenna. For best reception, it should be mounted parallel with the receiving antenna. The IC operates on a single supply voltage in the range 3V to 5V, but you should regulate the applied voltage to minimize frequency drift and noise.

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BH1417 Stereo PLL FM Transmitter

BH1417 Stereo PLL FM Transmitter Skema Rangkaian

This is the latest BH1417 FM Transmitter design from RHOM that includes a lot of features in one small package. It comes with pre-emphasis, limiter so that the music can be transmitted at the same audio level, stereo encoder for stereo transmission, low pass filter that blocks any audio signals above 15KHz to prevent any RF interference, PLL circuit that provides rock solid frequency transmission (no more frequency drift), FM oscillator and RF output buffer.

There are 14 possible transmission frequencies with 200KHz increments that users can select with a 4-DIP switch. Lower band frequencies start from 88.7 up to 89.9 MHz, and upper band frequencies start from 107.7 up to 108.9 MHz.

BH1417 can be supplied with 4 - 6 voltage and consumes only around 30mA, providing 20mW output RF power. BH1417 provides 40dB channel separation which is pretty good, although older BA1404 FM Transmitter chip provides slightly better 45dB channel separation.

BH1417 is only available in SOP22 IC case so this may be an inconvenience for some folks. On the other hand, because the chip is smaller than regular DIP-based ICs it is possible to fit the entire transmitter on a small PCB.

The bad news is that BH1417 requires 7.6MHz crystal oscillator, which is very hard to find. The good news is that you can use 7.68 MHz crystal instead, which is easier to find. In fact our BH1417 transmitter prototype (schematic shown above) uses 7.68 MHz crystal. This has absolutely no effect on stereo encoding process, we have tested it and stereo sound is crystal clear. The transmitted frequency on the other hand will be shifted up by exactly 1MHz (example: 88.1 MHz to 89.1 MHz) which is perfectly fine. The frequencies that are used in this project have been adjusted by 1MHz already so no additional conversion is necessary.

BH1417 chip may also be used a stand alone stereo encoder. The advantage of that is that you have full freedom of using a transmitter & amplifier of your choice. You will still have a pre-emphasis, limiter, stereo encoder and low pass filter in one small package because very few external components are required for these blocks. PIN 5 is MPX output that can be directly connected to an external FM transmitter through a 10uF cap.

BH1417 Block Diagram

Parts:
1x BH1417 - Stereo PLL Transmitter IC (Case SOP22)
1x 7.68 MHz Crystal
1x MPSA13 - NPN Darlington Transistor
1x 2.5 Turns Variable Coil
1x MV2109 - Varicap Diode
1x 4-DIP Switch
ANT - 30 cm of copper wire

1x 22K Resistor
7x 10K Resistor
1x 5.1K Resistor
2x 3.3K Resistor
1x 100 Ohm Resistor 1x 100uF Capacitor
3x 10uF Capacitor
2x 1uF Capacitor

1x 47nF Capacitor
3x 2.2nF Capacitor
1x 1nF Capacitor
1x 330pF Capacitor
2x 150pF Capacitor
1x 33pF Capacitor
2x 27pF Capacitor
1x 22pF Capacitor

2x 10pF Capacitor

sumber: http://electronics-diy.com

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BA1404 HI-FI Stereo FM Transmitter

BA1404 HI-FI Stereo FM Transmitter Skema Diagram

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.

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