Using 555 as FM transmitter Circuit Diagram

The integrated circuit 555 has no limits, this FM transmitter circuit, the IC 555 is designed as an stable multivibrator as usual. But the tension control pin is used to connect a piezoelectric element instead of the capacitor disk. The piezoelectric element generates a voltage and the output pin is connected to an antenna wire 30 inches for the transmission of signals.Just tap the piezo element and you can hear the sound on an FM radio station. The range is very short.

Using 555 as FM transmitter Circuit Diagram

2Km Fm Transmitter Shematic diagram with Explanation Circuit

This is a powerful transmitter so first of all I would like to tell you not to use this for illeagl things.You can transmitt signals from 2km.Use a matching antenna for this.





Note

# Don't give power without an antenna
# For L1 make 3 turns of 1mm enamelled copper wire on a 10mm diameter plastic former. On the same core make 2 turns of 1 mm enamelled copper wire close to L3 and that will be L2.
# by using R9 the gain can be controlled
# Inductor L3 can be a VK220J type RFC.
# This circuit operates with 9V to 18V ( Dont pass 24V)

Simple FM Transmitter Circuit Schematic With explanation

Simple FM Transmitter Circuit Schematic With explanation

This circuit uses a small microphone to capture the sound and some transistors to generate radio waves that can be picked up by a FM receiver like a car stereo.How it works:
From left to right, the first part is the microphone and some resistors to get it working. Next we have a capacitor and the first transistor, this amplifies the sound from the microphone so that it can be loud enough to work with. The last part, there is a transistor, a coil and some capacitors. This part generates the radio waves and combines them with the sound from the mic to transmit it thru the antenna.
The coil is made with about 9 turns of wire, use a pencil to get the right diameter for the coil. The capacitor with the arrow is called a trimmer capacitor, it has a small screw to adjust the value, we'll use it to tune a certain frequency or station to transmit on.

Simple FM Transmitter Circuit Schematic With explanation

(click to enlarge)

Versatile FM Transmitter Circuit Schematic With Explnation

Here is the circuit diagram of a versatile FM transmitter that doesn’t have a coil. The circuit is simple and easy to assemble.






The gate N1 acts as a buffer for strengthening the signals from the condenser microphone. The inverter N2 with its associated components forms a radio frequency oscillator in the FM region.The varicap diode BB109 is used for frequency modulating the audio signal to the carrier wave generated by the oscillator.Inverters N4 t0 N6 are used to drive the antenna.As the N4,N5,N6 are connected in parallel their effective output impedance is very less and can easily drive the antenna.


Notes.

* All electrolytic capacitors must be rated 10V.
* Use any general purpose condenser microphone.You can easily get one from old telephone or tape recorder.
* Use a 10 cm long wire as antenna.
* Gates N1 to N6 belong to same IC CD4069.
* The battery can be a 9V transistor radio battery.Adapters are not recommended because they would induce noise in the circuit.

Spy FM Transmitter Circuit Schematic With Explnation

This is so impotent circuit for us,Because we can use this circuit as a spy unit.This circuit can transmit signals about 30m.And the other important thing is the power of this circuit we can operate this circuit with 1.5v to 3v(1.8 mA at 1.5 Volts )


Note

# If you are unable to find the transistor here use these transistors Because here you can use equal transistors such as 2N2222A, BFxxx series, BC109B, C, and even well known BC238.

# Use 1.5v to 3v for this circuit.Don't supply more than 3v(3v can cover the max range 30m)

FM Transmitter 2 watt

The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz. Audio picked up and amplified by the electret microphone is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates the resonant frequency of the tank circuit (L1 coil and the trimcap) by varying the junction capacitance of the transistor. Junction capacitance is a function of the potential difference applied to the base of the transistor T2. The tank circuit is connected in a Hartley oscillator circuit.

Components List

R1=220K R2=4.7K R3,R4=10K R5=100ohm

C1,C2=4.7uF Electrolytic C3,C4=1nF C5=2-15pF C6=3.3pF

Q1=BC547C Q2=BD135 P1=25K MIC=Electret Condenser Type

P1 act as condenser microphone volume level. For FM, coil will be small. Use thin gauge enamel magnet wire. the diameter of coil will be a couple mm: use ink tube from pen to form, and try 8-12 turns. Small inductance coils make for much guess work.

( BH1415F ) FM Stereo Transmitter

This Electronic circuit is a stereo FM Transmitter based on BH1415F wireless audio link IC. Phase Locked Loop (PLL) controller use PIC16F628 and the the PLL frequency programming can be displayed with 8x2 and 16x2 LCD. Frequency Range 88-108 MHz

BH1415F can be supplied with 6 - 15V voltage, consumes only around 25mA while providing very sound quality and improved 40dB channel separation. BH1415 is only available in SOP22 IC case and 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 stereo coder on a small PCB.

Simplest Radio Transmitter

This is probably the simplest radio transmitter that you will find anywhere. It has a total of five parts and can be constructed into a very small space. It is great for science fair projects or other science related projects where short range transmission is useful.It runs on 1.5 to 3 Volts, with small hearing aid batteries or lithium “coin” cells being ideal. A thermistor or photoresistor can be inserted in series with R1 to have a varying output frequency dependent on the input.

The frequency can also be changed by changing the value of C1. A 2N2222 transistor is recommended, but you can try other types also. Performance tends to vary from type to type as well as from transistor to transistor. L1 is 20 to 30 turns of thin magnet wire (24 to 32 ga.) close wound around a 1/8 to 1/4″ diameter non-conductive form. The coil is tapped 1/3 of the way from one end and the tap connected to the emitter of Q1. Experiment with all of the values in this circuit. Nothing is critical, but performance can be varied considerabl

88-108 MHz Mono Modulated Fm Transmitter Circuit for House

This is a Fm Transmitter circuit for house.It
is a mono modulation type FM and Frequency range 88-108 MHz. Working voltage range 12-18 VDC and use current max at 450mA only. This circuit convenient for , because , have good small-sized. It is the ideal project for the beginner who wishes to get started in the fascinating world of FM broadcasting and wants a good basic circuit. This circuit use the transistor the important , be the number is 2N3553.

An Exciting product( BA1404 HI-FI Stereo FM Transmitter Kit)

hi fi stereo fm transmitter

Be “On Air” with your own radio station! BA1404 based transmitter is an exciting product 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.

RF Wireless FM Transmitter circuit and explanation

RF Wireless FM Transmitter

RF Wireless FM

Here’s a rf wireless FM transmitter can be built with simple, affordable and widely available parts. Construction is fun and much can be learned although performance is modest; for example, your voice gets difficult to hear at distances greater than 25 feet.

This FM transmitter is far from perfect offering only modest performance. First, tuning the transmitter can be frustrating. Even slight turns in the variable capacitor can result in large frequency changes. Second, transmitter tuning often resulted in a harmonic frequency. Instead of the intended 108 MHz for example, capacitor tuning yielded a 216 MHz transmitter frequency. In addition to hearing your voice one could slightly hear radio station broadcasts.

If performance is modest, why would I build this transmitter?

One answer is that much can be learned and this tutorial is is appendixed with the underlying mathematics to calculate parameters like (1) transmitter frequency, power output and range (2) antenna length and (3) required coil winding. Often on the web, one just finds a schematic. By adding the analysis (with high school level math), one can conceive improvements on transmitter performance.

RF Wireless Circuit

Construction
A combination of wire wrapping and soldering was used to construct the FM transmitter. Jameco’s prototyping card provides enough room for (non-critical) part placement. You should try to keep all parts close together and keep wire leads short.

RF Wireless-Inductor

RF Wireless-Bottom

RF Wireless FM Transmitter Operation
First, use a battery-powered pocket radio as a receiver. AC powered boom-boxes and home stereos (110 or 220 V) are not recommended; battery-powered radios are much better at receiving transmissions than AC-powered units.

1. Tune your radio to dead air, i.e. frequencies within the FM radio band that are silent or only have some hiss. Frequencies near 108 MHz are typically dead air. The Radio-Locator web page lists local radio stations in your area. This can help you identify dead air frequencies.
2. Turn on your RF wirelessFM transmitter, extend its antenna and keep the transmitter approximately 2 feet away from your FM radio. Speak into the mic while slowly adjusting the variable cap. Use your fingernail or non-metallic screwdriver until you hear yourself over the radio. This process is frustratingly tedious, requiring careful capacitor tuning. You are tuned once you hear howling (also known as a hot mic) which indicates transmitter-receiver feedback.
3. Increase the transmitter-to-radio distance. Congratulations – you have a rf wireless microphone!

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3 Watt FM Transmitter This is the schematic for an FM transmitter with 3 to 3.5 W output power that can be used between 90 and 110 MHz. Although the

3 Watt FM Transmitter

This is the schematic for an FM transmitter with 3 to 3.5 W output power that can be used between 90 and 110 MHz. Although the stability isn't so bad, a PLL can be used on this circuit.

Schematic
This is the schematic of the 3W FM Transmitter

Parts

Part Total Qty. Description Substitutions
R1,R4,R14,R15 4 10K 1/4W Resistor
R2,R3 2 22K 1/4W Resistor
R5,R13 2 3.9K 1/4W Resistor
R6,R11 2 680 Ohm 1/4W Resistor
R7 1 150 Ohm 1/4W Resistor
R8,R12 2 100 Ohm 1/4W Resistor
R9 1 68 Ohm 1/4W Resistor
R10 1 6.8K 1/4W Resistor
C1 1 4.7pF Ceramic Disc Capacitor
C2,C3,C4,C5,C7,
C11,C12 7 100nF Ceramic Disc Capacitor
C6,C9,C10 3 10nF Ceramic Disc Capacitor
C8,C14 2 60pF Trimmer Capacitor
C13 1 82pF Ceramic Disc Capacitor
C15 1 27pF Ceramic Disc Capacitor
C16 1 22pF Ceramic Disc Capacitor
C17 1 10uF 25V Electrolytic Capacitor
C18 1 33pF Ceramic Disc Capacitor
C19 1 18pF Ceramic Disc Capacitor
C20 1 12pF Ceramic Disc Capacitor
C21,C22,C23,C24 4 40pF Trimmer Capacitor
C25 1 5pF Ceramic Disc Capacitor
L1 1 5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L2,L3,L5,L7,L9 5 6-hole Ferroxcube Wide band HF Choke (5 WDG)
L4,L6,L8 3 1.5 WDG, Dia 6 mm, 1 mm CuAg, Space 1 mm
L10 1 8 WDG, Dia 5 mm, 1 mm CuAg, Space 1 mm
D1 1 BB405 BB102 or equal (most varicaps with C = 2-20
pF [approx.] will do)
Q1 1 2N3866
Q2,Q4 2 2N2219A
Q3 1 BF115
Q5 1 2N3553
U1 1 7810 Regulator
MIC 1 Electret Microphone
MISC 1 PC Board, Wire For Antenna, Heatsinks

Notes

1. The circuit has been tested on a normal RF-testing breadboard (with one side copper). Make some connections between the two sides. Build the transmitter in a RF-proof casing, use good connectors and cable, make a shielding between the different stages, and be aware of all the other RF rules of building.

2. Q1 and Q5 should be cooled with a heat sink. The case-pin of Q4 should be grounded.

3. C24 is for the frequency adjustment. The other trimmers must be adjusted to maximum output power with minimum SWR and input current.

4. Local laws in some states, provinces or countries may prohibit the operation of this transmitter. Check with the local authorities.

VHF Radio FM Transmitter Circuit

Here’s a VHF Radio FM transmitter. This project is a simple VHF FM transmitter using only one crystal and will cover 145.00 to 146.00 MHz. The crystal is a 44.9333 MHz crystal for 145.500 receive, as used in the Trio (Kenwood) 2200, PYE, Motorolla, Tait equipment, to name but four. The frequency of the crystal is not critical as almost any other xtal for the 2-meter band will function.

VHF Radio Transmitter

No provision has been made to tune the vhf radio transmitter to different channels, as this transmitter was first used as a single channel “repeater box”, leaving my main rig free to be used on other channels. The transmitter circuit is given above and simply mixes the output of a (more or less) conventional receiver multiplier (x3) with the output of a 10.7MHz VFO that is modulated with true FM.

Ordinary 1N4001 diodes will function well as varicap diodes, but if true varicap diodes (such as BA102 etc.) are used you will have to reduce the value of the 18pf capacitor coupling D1/D2 to L1. L1 may be a 10.7MHz IF transformer robbed from a domestic receiver, but remove the internal capacitor. Adjust L1 (10.2 – 11.2 MHz) to cover 145-146 MHz.

The transmitter modulator is a simple circuit which I will post later. Two OP-Amps were used in the prototypes, the first was a MIC amplifier to bring the MIC AF OP up to 500mV RMS. Clamp the AF with a couple of back-to-back diodes (limiter) then the second OP-Amp amplifies the clipped AF to the correct level, (about 1.5v RMS) for 5KHz deviation. Adjust the gain of the first OP-AMP for MIC GAIN and adjust the gain of the second OP-AMP for deviation (with FULL AF).

Audio Modulator

The output of the transmitter amplifier driver will supply about 10-20mW to the PA. I didn’t use a Power Amplifier because I lived so close to the repeater (path loss = -109dB). There are hundreds of VHF QRP PA’s published in SPRAT, INTERNET, RSGB books, RadCom, and PACKET RADIO so I will leave that to your own ingenuity. A single transistor, such as the 2N3866 will be more than adequate to get up to 250mW, but an additional band-pass tuned circuit should be used between them.

Browse: VHF Radio Transmitter on Amazon

See more: Wireless Transmitter

Source: FM Transmitter

FM Transmitter for MP3 Player

Do you have an idea 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, and many other audio sources. This 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.

FM Transmitter Schematic

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.

FM Transmitter Printed Circuit Board
This a suggested high-resolution PCB layout for BA1404 Transmitter. It is ready for printing and no further adjustments are necessary. Dimensions of the PCB should be 57 mm x 35 mm (W x H).

FM Transmitter PCB

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See More: Audio Video Transmitter

Source: BA1404 Stereo FM Transmitter

VHF Radio FM Transmitter Circuit

VHF Radio FM Transmitter Circuit

Here’s a VHF Radio FM transmitter. This project is a simple VHF FM transmitter using only one crystal and will cover 145.00 to 146.00 MHz. The crystal is a 44.9333 MHz crystal for 145.500 receive, as used in the Trio (Kenwood) 2200, PYE, Motorolla, Tait equipment, to name but four. The frequency of the crystal is not critical as almost any other xtal for the 2-meter band will function.

VHF Radio Transmitter

No provision has been made to tune the vhf radio transmitter to different channels, as this transmitter was first used as a single channel “repeater box”, leaving my main rig free to be used on other channels. The transmitter circuit is given above and simply mixes the output of a (more or less) conventional receiver multiplier (x3) with the output of a 10.7MHz VFO that is modulated with true FM.

Ordinary 1N4001 diodes will function well as varicap diodes, but if true varicap diodes (such as BA102 etc.) are used you will have to reduce the value of the 18pf capacitor coupling D1/D2 to L1. L1 may be a 10.7MHz IF transformer robbed from a domestic receiver, but remove the internal capacitor. Adjust L1 (10.2 – 11.2 MHz) to cover 145-146 MHz.

The transmitter modulator is a simple circuit which I will post later. Two OP-Amps were used in the prototypes, the first was a MIC amplifier to bring the MIC AF OP up to 500mV RMS. Clamp the AF with a couple of back-to-back diodes (limiter) then the second OP-Amp amplifies the clipped AF to the correct level, (about 1.5v RMS) for 5KHz deviation. Adjust the gain of the first OP-AMP for MIC GAIN and adjust the gain of the second OP-AMP for deviation (with FULL AF).

Audio Modulator

The output of the transmitter amplifier driver will supply about 10-20mW to the PA. I didn’t use a Power Amplifier because I lived so close to the repeater (path loss = -109dB). There are hundreds of VHF QRP PA’s published in SPRAT, INTERNET, RSGB books, RadCom, and PACKET RADIO so I will leave that to your own ingenuity. A single transistor, such as the 2N3866 will be more than adequate to get up to 250mW, but an additional band-pass tuned circuit should be used between them.

Browse: VHF Radio Transmitter on Amazon

See more: Wireless Transmitter

Source: FM Transmitter

1W AM Transmitter

This AM transmitter circuit provides a nice, clean output of about 1 Watt (carrier power). Though designed for the medium wave band (circa 1.5 MHz) it would work equally well on higher frequencies (6.2 MHz for example) with a few tweaks in component values (see table on left - C15 should be adjusted for maximum output).

The carrier (produced by the 4049) is modulated at low-level by the MC1496 balanced modulator. There are then a couple of stages of linear amplification to reach the final output power so no modulation transformer is required. TR2, TR5 and TR6 are BC108 or similar; TR3 is a 2N3053 or 2N4427 or 2N3866 or any low/medium power NPN transistor. The main output transistors, TR4 and TR5 were originally 2SC1162 but BD135 or BD139 or other medium power RF transistors will do equally well. T1 uses a pre-tuned TOKO KANK3334 coil, the other transformers are wound on the red T50-2 toroids (the number of turns shown is the ratio, use about 4 to 5 times that number in reality - less athigher frequencies). The LED lights up if current in the output amplifier goes too high, so it's a kind of 'high SWR' warning.

Source: ZFM

Stereo FM Transmitter Based BH1417 Chips

This electronic circuit is a 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.


Parts List:
1x BH1417 - Stereo PLL Transmitter IC (Case SOP22) (datasheet)
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

Specifications:
Supply Voltage: 4 - 6V
Transmission Frequency: 87.7 - 88.9MHz, 106.7 - 107.9MHz (200kHz steps)
Output RF Power: 20mW
Audio Frequency: 20 - 15KHz
Separation: 40dB
Power Consumption: 30mA

Frequency Selection / Calibration
Frequency selection is very straight forward. Simply select transmission frequency at which you would like to transmit, set the combination for 4-DIP switch and BH1417 will immediately tune to that frequency. If you can't hear the transmitted audio signal on your FM receiver then re-adjust 2.5 turn variable coil until you can hear the signal. If you have a laboratory power supply you may try to vary the voltage supply from 4 to 6V. While doing that BH1417 will automatically vary the voltage for MV2109 varicap diode making sure that there's no frequency drift.


Source

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

« FM Receiver Auto Battery Charger » Wireless FM Transmitter FM Transmitter USB Powered Wireless FM Transmitter Circuit Here’s a Wireless FM tran

FM Transmitter

USB Powered Wireless FM Transmitter Circuit

Here’s a Wireless FM transmitter circuit powered from USB ports that could be used to play audio files on a standard VHF FM radio. The transmitter circuit use no coils that have to be wound. This FM transmitter can be used to listen to your own music throughout your home. When this FM transmitter used in the car, there is no need for a separate input to the car stereo to play back the music files from your MP3 player.

This FM transmitter use a chip made by Maxim Integrated Products, the MAX2606 [1]. This IC from the MAX2605-MAX2609 series has been specifically designed for low-noise RF applications with a fixed frequency. The VCO (Voltage Controlled Oscillator) in this IC uses a Colpitts oscillator circuit. The variable-capacitance (varicap) diode and feedback capacitors for the tuning have also been integrated on this chip, so that you only need an external inductor to fix the central oscillator frequency.

Transmitter Schematic

It is possible to fine-tune the frequency by varying the voltage to the varicap. Not much is demanded of the inductor, a type with a relatively low Q factor (35 to 40) is sufficient according to Maxim. The supply voltage to the IC should be between 2.7 and 5.5 V, the current consumption is between 2 and 4 mA. With values like these it seemed a good idea to supply the circuit with power from a USB port.

A common-mode choke is connected in series with the USB connections in order to avoid interference between the circuit and the PC supply. There is not much else to the circuit. The stereo signal connected to K1 is combined via R1 and R2 and is then passed via volume control P1 to the Tune input of IC1, where it causes the carrier wave to be frequency modulated. Filter R6/C7 is used to restrict the bandwidth of the audio signal. The setting of the frequency (across the whole VHF FM broadcast band) is done with P2, which is connected to the 5 V supply voltage.

The transmitter PCB designed uses resistors and capacitors with 0805 SMD packaging. The size of the board is only 41.2 x 17.9 mm, which is practically dongle-sized. For the aerial an almost straight copper track has been placed at the edge of the board. In practice we achieved a range of about 6 metres (18 feet) with this. There is also room for a 5-way SIL header on the board. Here we find the inputs to the 3.5 mm jack plug, the input to P1 and thesupply voltage . The latter permits the circuit to be powered independently from the mains supply, via for example three AA batteries or a Lithium button cell. Inductor L1 in the prototype is a type made by Murata that has a fairly high Q factor: minimum 60 at 100 MHz.

Transmitter PCB

P1 has the opposite effect to what you would expect (clockwise reduces the volume), because this made the board layout much easier. The deviation and audiobandwidth varies with the setting of P1. The maximum sensitivity of the audio input is fairly large. With P1 set to its maximum level, a stereo input of 10 mVrms is sufficient for the sound on the radio to remain clear. This also depends on the setting of the VCO. With a higher tuning voltage the input signal may be almost twice as large (see VCO tuning curve in the data sheet). Above that level some audible distortion becomes apparent. If the attenuation can’t be easily set by P1, you can increase the values of R1 and R2 without any problems.

Measurements with an RF analyzer showed that the third harmonic had a strong presence in the transmitted spectrum (about 10 dB below the fundamental frequency). This should really have been much lower. With a low-impedance source connected to both inputs thebandwidth varies from 13.1 kHz (P1 at maximum) to 57 kHz (with the wiper of P1 set to 1/10).

In this circuit the pre-emphasis of the input is missing. Radios in Europe have a built-in de-emphasis network of 50 ?s (75 ?s in the US). The sound from the radio will therefore sound noticeably muffled. To correct this, and also to stop a stereo receiver from mistakenly reacting to a 19 kHz component in the audio signal, an enhancement circuit is published elsewhere in this issue (Pre-emphasis for FM Transmitter, also with a PCB). Author: Mathieu Coustans, Elektor Magazine, 2009

MP3 FM Transmitter Parts List
Resistors (all SMD 0805)
R1,R2 = 22k?
R3 = 4k?7
R4,R5 = 1k?
R6 = 270?
P1 = 10k? preset, SMD (TS53YJ103MR10 Vishay Sfernice, Farnell # 1557933)
P2 = 100k? preset, SMD(TS53YJ104MR10 Vishay Sfernice, Farnell # 1557934)
Capacitors (all SMD 0805)
C1,C2,C5 = 4?F7 10V
C3,C8 = 100nF
C4,C7 = 2nF2
C6 = 470nF
Inductors
L1 = 390nF, SMD 1206 (LQH31HNR39K03L Murata, Farnell # 1515418)
L2 = 2200? @ 100MHz, SMD, common-mode choke, 1206 type(DLW31SN222SQ2L Murata, Farnell #1515599)
Semiconductors
IC1 = MAX2606EUT+, SMD SOT23-6 (Maxim Integrated Products)
Miscellaneous
K1 = 3.5mm stereo audio jack SMD (SJ1-3513-SMT
CUI Inc, DIGI-Key # CP1-3513SJCT-ND)
K2 = 5-pin header (only required in combination with 090305-I pre-emphasis circuit)
K3 = USB connector type A, SMD (2410 07 Lumberg, Farnell # 1308875)

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See more: FM Transmitter Antenna

Source: FM Transmitter for MP3 Player Powered from USB

Synthesised WideBand FM Transmitter This project is a complete crystal-controlled Wide Band Frequency Modulated (WBFM) transmitter delivering a power

This project is a complete crystal-controlled Wide Band Frequency Modulated (WBFM) transmitter delivering a power output in the order of 10 milli-watts (+10dBm) using simple components. The transmitter is based upon the Phase-Locked Loop (PLL) principle, but due to the circuit's simplicity a true "phase lock" can never be achieved.

The transmitter has both 1v peak-to-peak 'LINE' input and 10mV 'MIC' audio inputs. These will accept audio input sources from external equipment, such as hi-fi, CD and computer equipment. The microphone input also has an in-built power source to energise an 'Electret' type condenser
microphone. The Radio Frequency (RF) output circuitry includes a three-pole filter for reduction of harmonics and other spurious signals. The spurious output signal level is better than -40dBc (0.0001 times the power of the wanted signal level), which makes the project suitable for driving an external power amplifier.The transmitter is powered from a 12v supply, but it will operate from 9 Volts to 16 Volts. The DC power input is equipped with a diode (D1), which protects the transmitter in the event the supply voltage is inadvertently connected the wrong way round.

Download Kit Intro Datasheet