For months I’ve been looking for a simple FM
BUG project, the ones online require inductors which you either have to
acquire or build, if you don’t have a LCR meter it becomes rather hard
to get the circuit working, specially if you’re a beginner without an
oscilloscope! – Sometimes they don’t even tell you which inductance is
required and you have to calculate an estimate, which is the main reason
why many high frequency RF projects fail in the first place. This
circuit on the other hand performs pretty well, even if you’re
manipulating the board or touching the coax it will stay within the
tuned frequency (unless you touch the transistor or timing capacitor!).
Posted on Saturday, February 16, 2013 • Category: FM Transmitters
The objective of this 3V FM Transmitter
design is to provide a simple low-power transmitter solution for
broadcasting audio from various audio sources. This transmitter
transmits audio using small sensitive microphone. Transmitter's
frequency, as built is tunable via 15pF trimmer to the desired
frequency, and the coil is embedded on the circuit board. This
implementation is adapted to rebroadcast the output of a CD player,
television receiver, or radio receiver. I use this transmitter so that I
can move about the house and listen to my favorite programs without
disturbing others. Within and the house, I find that I can get 50 to 100
meters away from the transmitter with the small pocket FM receiver I
carry in my shirt pocket.
Posted on Sunday, February 10, 2013 • Category: FM Transmitters
This little broadcast FM transmitter has
500mW of RF output power and runs of 12-15V battery or power supply. DC
whose signal modulated by FM using four transistors. Transmitter
includes four transmitter stages and draws around 100-150mA of current.
Using the values of the circuit components, the frequency will be around
100 MHz but can be changed via coil. Through the 5 pF capacitor and 10K
ohm resistor, the modulation of audio signal is supplied to the tank
circuit. The amount of modulation is being managed by the 1N4002, a
general purpose rectifier diode. FM Transmitter's output stage is
functioning as a class D amplifier where the output transistors act as a
switch.
Posted on Wednesday, January 16, 2013 • Category: FM Transmitters
There are many miniature FM transmitter bug
circuits online, this one is unique in that it runs completely on solar
power. No battery is required. As long as the sun is shining on the PV
panel, the transmitter will transmit. The transmitter bug is useful as a
"remote ear", and can be used for anything from listening birds to
surveillance work. The mic preamp and oscillator circuits were borrowed
from a common circuit found around the Internet, a regulated solar power
supply and an RF amp that extends the range of transmitter and improves
frequency stability were added.
Posted on Sunday, December 23, 2012 • Category: FM Transmitters
Build your own simple mini FM transmitter.
This fun project will show you how to build a mini broadcasting
transmitter that can transmit an audio signal up to a quarter mile to
any FM receiver. It's easy to build and a good learning experience. It
serves as a hands-on learning tool for students or anybody interested in
electronics. Having a range of up to a quarter mile, it's great for a
house security system, baby monitoring device or simply a listening
gadget that you can place anywhere!
Posted on Tuesday, December 4, 2012 • Category: FM Transmitters
The power output of many transmitter
circuits are very low because no power amplifier stages are
incorporated. The transmitter circuit described here has an extra RF
power amplifier stage using 2N3866 RF power transistor after the
oscillator stage to increase output power to 250 milliwatts. With a good
matching 50-ohm ground plane antenna or multi-element Yagi antenna,
this transmitter can provide reasonably good signal strength up to a
distance of about 2 kilometers. Transmitter's oscillator is built around
BF494 transistor T1. It is a basic low-power variable-frequency VHF
oscillator. A varicap diode circuit is included to tune the frequency of
the transmitter and to provide frequency modulation by audio signals.
The output of the oscillator is about 50 milliwatts. 2N3866 transistor
T2 forms a VHF-class A power amplifier. It boosts the oscillator signal
power four to five times. Thus 250mW of power is generated at the
collector of transistor T2.
Posted on Sunday, November 18, 2012 • Category: FM Transmitters
Presented FM transmitter bug is built using
BF414 / BF324 / BF606 transistor. The 30cm antenna has a range of about
30m in the building, more in the open field. Power supply 2x AAA
batteries have been used with voltage of 2.75 V. I added resistor 10K in
parallel with 1.5pF capacitor so that the system works well when
connected to an external source (mp3 player / computer). On the computer
I had to reduce sound to about 35% of capacity, so that I do not have
clipping. I managed to improve transmitter stability with simple
shielding. The coil is 5 turns of enameled copper wire wound on 1 mm ø =
5 mm.
Posted on Friday, October 26, 2012 • Category: FM Transmitters
BA1404 transmitter includes onboard RF
amplifier for increased transmitting range. Operating voltage range is
1-3V, the circuit contains FM stereo mixer, 38KHZ oscillator, FM
modulator and high-frequency amplifier monolithic integrated circuit. As
the "electronic newspaper" BBS there are many users requiring detailed
information on the FM stereo transmitter, so I re-collect the relevant
information on the simple discrete, merge, integrated FM stereo
transmitter experiment, that BA1404 with μpc1651 mix of the most easy to
make and debug, and very high frequency stability (relative to the
previous circuit BA1404), transmission power is increased by UPC1651RF
amplifier.
Posted on Sunday, October 7, 2012 • Category: FM Transmitters
A high quality stereo FM transmitter circuit
is shown here. The circuit is based on the IC BA1404 from ROHM
Semiconductors. BA1404 is a monolithic FM stereo modulator that has
built in stereo modulator, FM modulator, RF amplifier circuitry. BA1404
FM transmitter can be operated from 76 to 108MHz and power supply for
the circuit can be anything between 1.25 to 3 volts.
Posted on Sunday, September 16, 2012 • Category: FM Transmitters
Here is a simple USB FM transmitter that
could be used to play audio files from an MP3 player or computer on a
standard VHF FM radio by connecting it to an USB port. The circuit use
no coils that have to be wound. This USB transmitter can be used to
listen to your own music throughout your home. To keep the fm
transmitter circuit simple as well as compact, it was decided to use a
chip made by Maxim Integrated Products, the MAX2606. 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.
Posted on Monday, August 20, 2012 • Category: FM Transmitters
This easy to build FM transmitter bug can
transmit voice to exceptionally good range. Tune trimmer to hear the
signal to your near radio. Transmitter frequency range is 88-108 MHz.
Max current consumption is 30mA. You can power the fm transmitter bug
with a 9Volt Battery, or you can plug a power supply to feed in 9-12
Volts. That bug will pick even a low whisper or even the sound of a
breath well far from the microphone. Great spy transmitter equipment.
Posted on Saturday, June 23, 2012 • Category: FM Transmitters
After building FM transmitter I decided to
build a 6W RF Transmitter amplifier for the FM band to get more power
and we chose to copy a 6 Watt design built around 2SC1971 RF power
transistor. We were not satisfied with finished result and decided to
replace the fixed capacitors around the pcb inductors with variable
capacitors, this is much better and possible to tune to your transmitter
frequency.
Posted on Friday, June 8, 2012 • Category: FM Transmitters
The 1 watt 20 meter QRP transmitter with
VXO. This is a nice QRP transmitter that can be used in combination of
one of the simple receivers.
Normally these designs have only two transistors: one is the X-tal
oscillator and the second the final amplifier. A good example is my
first QRP rig that is also described somewhere on this site. Here the
VXO (Variabele X-tal Oscillator) has a tuning range of 16 kHz. This VXO
is buffered with an extra driver stage for a better frequency stability
and a varicap diode is used instead of a variabele capacitor. An extra
transistor is added for keying the transmitter with a low keying
current.
What you can do with such a simple 1 watt QRP power transmitter.
This is a real low power transmitter, so do not expect that you can do
everything with it but...
When conditions are normal, you can easily make many QSO's during one
afternoon with stations with distances upto 2000 km with a simple
inverted V wire dipole antenna! From Europe, I did even make QSO's
across the Ocean!
Posted on Tuesday, May 29, 2012 • Category: FM Transmitters
This PLL transmitter is controlled and the
frequency is very stable and can be programmed digitally. Transmitter
will work 88-108 MHz and output power up to 500mW. With a small change
can set the frequency of 50-150 MHz. The output power is often set to
several watts with transistors. So therefore I decided to build a simple
transmitter with great performances. The frequency of this transmitter
can easily be changed by software and space / compress air coil. This
transmitter is the oscillator colpitts. Oscillator is a VCO (voltage
controlled oscillator) which is set by the PLL circuit and PIC micro
controller. This oscillator is called the Colpitts oscillator and
voltage controlled to achieve the FM (frequency modulation) and PLL
control.
Posted on Wednesday, May 2, 2012 • Category: FM Transmitters
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.
Stability of this transmitter is not bad and PLL circuit can be added
on.
This is a circuit that I've build a few years ago for a friend, who used
it in combination with the BLY88 amplifier to obtain 20 W output power.
From the notes that I made at the original schematic, it worked fine
with a SWR of 1 : 1.05 (quite normal at my place with my antenna).
Posted on Sunday, April 1, 2012 • Category: FM Transmitters
A simple 200mW FM Transmitter circuit which
covers frequencies from 88 to 108 MHz. It is built with 3 transistors:
BC109, BFR91A and BFR96S. It is quite stable and the output power is
around 200mW.
The first stage of transmitter is a mic amplifier but if you connect
this radio transmitter directly to an audio source you can remove this
stage and connect the audio signal to R5.
U1, 1PH51C can be replaced with LM7805. You must use a stabilized power
source for oscillator stage to prevent frequency variation. You can
remove C7 and use a linear potentiometer instead of R6 with the median
connector to C4, one pin to ground and the other one to +. FM
Transmitter uses MV2109 varicap diode and C7 for frequency tuning.
Posted on Tuesday, March 20, 2012 • Category: FM Transmitters
The RF oscillator using the inverter N2 and
10.7Mhz ceramic filter is driving the parallel combination of N4 to N6
through N3.Since these inverters are in parallel the output impedance
will be low so that it can directly drive an aerial of 1/4th wavelength.
Since the output of N4-N6 is square wave there will be a lot of
harmonics in it. The 9th harmonics of 10.7Mhz (96.3Mhz) will hence be at
the center of the FM band. N1 is working as an audio amplifier. The
audio signals from the microphone are amplified and fed to the varicap
diode. The signal varies the capacitance of the varicap and hence varies
the oscillator frequency which produce Frequency Modulation.
Posted on Wednesday, February 15, 2012 • Category: FM Transmitters
With this circuit you can build a very small
tracking transmitter that can be tracked using a FM broadcast band
radio receiver. The transmitter can be powered from any 1.5V volt
battery or power supply. Transmitter has a range up to 1 mile depending
on battery voltage, height above ground, receiver sensitivity, and
antenna length. Under certain conditions distances of 1 mile have been
achieved. It is recommended that this transmitter be used with FM radios
that can tune continuously across the dial. The better the receiver and
receiver antenna system the greater the practical range of the
transmitter, however good functionality can be achieved with the least
expensive radios and using only the standard telescoping antenna
included with most radios.
Posted on Tuesday, February 7, 2012 • Category: FM Transmitters
Here's BH1417 USB FM Transmitter with
built-in PLL circuit. Its low-frequency signal is converted into
high-frequency, which can take any audio device with FM radio (stereo,
car CD, MP3, DVD player, etc.), as a normal radio station. Transmitter
power is sufficient for reliable reception of its signal within a few
tens of meters. The basis of the device is a chip BH1417F, included in a
typical scheme. This device contains all the necessary circuitry to
generate a composite stereo signal c of the pilot tone, the RF generator
with PLL and power amplifier. A detailed description is given in.
Posted on Wednesday, February 1, 2012 • Category: FM Transmitters
Here's a long range 300mW FM Transmitter for
the 88MHz to 108MHz band. This particular TX is of special interest to
those wishing to build low power Power Amplifiers for the VHF bands
since it used impedance matching, power amplifier and antenna filtering,
all of which should be used by radio constructors, whether it be for
amateur radio or any other form of radio. The features of this project
are: Higher output power - 150mW min (at 9v) and 300mW+ (at 12.5v). Very
pure output signal due to careful design and filtering. VARICAP
modulation - possibility to add a synthesizer. Single sided Printed
Circuit Board, only 40mm x 72mm. Covers the domestic FM band - 88MHz to
108MHz. Easy to build, but coil winding experience IS required
Posted on Tuesday, January 17, 2012 • Category: FM Transmitters
The objective of this 1.5V FM Broadcast
Transmitter design is to provide a simple low-power transmitter solution
for broadcasting audio from various audio sources. This transmitter
accepts stereo input via two 470K resistors. Since there is no audio
level control on the input, the audio level out from the source needs to
be adjusted. Or, you can just add a 10k as an input level control.
Transmitter's frequency, as built is tunable via spreading or
compressing the coil to the desired frequency, and the coil can be glued
down. If you want to make one that's tunable, it might be easiest to
reduce the 18 pf capacitor and put a small trimmer capacitor in parallel
with the inductor (across the reduced value capacitor). Voltage
variable capacitors would be an nice alternative to a mechanical
variable capacitor but they don't offer much tuning range with only a
1.5V power supply.
Posted on Sunday, January 8, 2012 • Category: FM Transmitters
This FM Broadcast Transmitter circuit will
transmit a continuous audio tone on the FM broadcast band (88-108 MHz)
which could used for remote control or security purposes. Circuit draws
about 30 mA from a 6-9 volt battery and can be received to about 100
yards. A 555 timer is used to produce the tone (about 600 Hz) which
frequency modulates a Hartley oscillator. A second JFET transistor
buffer stage is used to isolate the oscillator from the antenna so that
the antenna position and length has less effect on the frequency. Fine
frequency adjustment can be made by adjusting the 200 ohm resistor in
series with the battery. Oscillator frequency is set by a 5 turn tapped
inductor and 13 pF capacitor.
Posted on Friday, December 30, 2011 • Category: FM Transmitters
Here is a very simple telephone broadcaster
transmitter which can be used to eavesdrop on a telephone conversation.
The circuit can also be used as a wireless telephone amplifier.
One important feature of this phone transmitter is that the circuit
derives its power directly from the active telephone lines, and thus
avoids use of any external battery or other power supplies.
Posted on Wednesday, December 28, 2011 • Category: FM Transmitters
In this project, you will make a simple
3-stage low-power broadcast-type circuit, using a crystal oscillator
integrated circuit and an a collector modulated AM oscillator with
amplifier. You can connect the circuit to the an electred microphone or
amplified dynamic microphone. Using an electred microphone is shown (in
gray) in the diagram below. (no amplified dynamic microphone has a to
low output voltage to work. at least 100mv is needed). You could also
add a LF preamp stage of one transistor to allow connecting a dynamic
microphone directly.
You'll see that you can receive the signal through the air with almost
any AM radio receiver. Although the circuits used in radio stations for
AM receiving are far more complicated, this nevertheless gives a basic
idea of the concept behind a principle transmitter. Plus it is a lot of
fun when you actually have it working!
Remember that transmitting on the 10 meter band you'll need a valid
radioamateur license!!
A wide range of different circuits have been used for AM, but one of the
simplest circuits uses collector modulation applied via (for example) a
transformer, while it is perfectly possible to create good designs
using solid-state electronics as I applied here (T1 BC557).
The transmitter is build as a Colpitts Oscillator with a BSX20
transistor. HF-output of the oscillator is approx. 50 mW, depending on
the supply voltage of 6 to 15 Volts. This is amplified by the BD135 and
brings the power up to approx. 1 watt @ 12volts. The transmit frequency
is stabilized with the 28Mhz crystal. A slight detuning of approx 1kc is
possible when using a 120pF trimmer capacitor for C8. The oscillator
signal is taken from the collector of T2 and guided to the input of T3
which output is lead via an L-filter and low-pass PII filter circuit
cleaning up the signal pretty good and ensuring spectral purity. The
oscillator is keyed by T1 and the morse key (S). By keying the morse-key
T1 is not been used for modulation and is biased, hence lets T2 freely
oscillate.
Posted on Thursday, December 15, 2011 • Category: FM Transmitters
This small FM transmitter with a range of
about 50 meters designed for hoby. With lots of mini-transmitters then
you have a comprehensive, action-packed radio program. Due to the power
supply via the USB port of a high frequency stability is achieved.
Alternatively, the receiver, a battery 5 to 12 volts to operate.
Posted on Tuesday, December 6, 2011 • Category: FM Transmitters
Here are instructions for building your own
ipod FM radio transmitter. It works quite easy, there is a power switch
on the bottom to turn it on and tune your radio and transmitter to the
right frequency. For the antenna you can use a copper wire of 70 cm. The
range of this FM transmitter is about 100 to 150 meters (500 feet).
With R5 you can adjust the input signal and with C6 you can tune your
frequency. Transmitter is supplied by 9V battery.
Posted on Friday, December 2, 2011 • Category: FM Transmitters
With this Stereo FM Transmitter with BA1404
you will be able to create a mini stereo FM station and broadcast to
your entire home, a simple way to have an audio link wireless with ease.
With the FM transmitter BA1404 Hifi Stereo you can stream your music
from your iPod MP3, satellite receiver, computer, DVD player, Mobile
Phone, MP4 player and MP3 and other audio source directly to an FM
receiver with crystal clear sound.
Posted on Friday, November 18, 2011 • Category: FM Transmitters
Here's simple FM transmitter circuit using
medium power 2N2218 transistor. Micropohone is of electret type that
connects to two input terminals and the antenna should be a copper wire
from 15 to 40 cm. Below is schematic circuit of the fm transmitter.
Posted on Friday, October 28, 2011 • Category: FM Transmitters
Here's 1W RF Amplifier is for boosting
small fm transmitters and bugs. It use two Philips 2N4427 and its power
is about 1Watt. At the output you can drive any linear with BGY133 or
BLY87 and so on. Its power supply has to give 500mA current at 12 Volts.
More voltage can boost the distance but the transistors will be burned
much earlier than usual.! In any case do not exceed the 15Volts. The Amp
offers 15 dB in the area of 80Mhz to 110 Mhz. L4, L5, and L6 are 5mm
diameter air coils, 8 turns, with wire 1mm wire diameter.An easy
project, with great results.
Posted on Sunday, October 23, 2011 • Category: FM Transmitters
A high quality stereo FM transmitter circuit
is shown here. The circuit is based on the IC BA1404 from ROHM
Semiconductors. BA1404 is a monolithic FM stereo modulator that has
built in stereo modulator, FM modulator and RF amplifier. The FM
modulator can be operated from 76 to 108MHz and power supply for the
circuit can be anything between 1.25 to 3 volts.
In the circuit R7, C16, C14 and R6, C15, C13 forms the pre-emphasis
network for the right and left channels respectively. This is done for
matching the frequency response of the FM transmitter with the FM
receiver. Inductor L1 and capacitor C5 is used to set the oscillator
frequency. Network C9,C10, R4,R5 improves the channel separation. 38kHz
crystal X1 is connected between pins 5 and 6 of the IC. Composite stereo
signal is created by the stereo modulator circuit using the 38kHz
quartz controlled frequency.
Posted on Tuesday, October 18, 2011 • Category: FM Transmitters
This simple FM Transmitter takes audio input
through a 1/4" phono jack and, constructed as shown, without the
optional antenna connections, will broadcast an FM radio signal about 30
feet. This is the standard model of simplest FM transmitters includes a
trim capacitor to adjust the transmitting frequency. It can be powered
by a 9V battery and uses a hand-turned copper coil. The circuit is
extraordinarily simple and could be built on perfboard or on a panel
almost as easily.
Posted on Wednesday, October 12, 2011 • Category: FM Transmitters
This is a simple design of a small FM
Transmitter Bug that's perfect for transmitting and eavesdropping
purposes. Due to the high sensitivity, even the ticking of the clock to
hear. The range is estimated at anything from 50 meters. With a small
piece of wire as an antenna to get at least the whole house. L1 and L2
are two equal air pools. They each consist of 5 turns at a diameter of
about 4 mm. The thickness of the wire does not matter, 0.5 mm works
perfectly. C4 is the frequency adjustment. Tune an FM radio in an empty
area of the FM band and C4 to turn your silence or hear a whistle. From
what you can precisely adjust the radio and the transmitter installed in
a room somewhere to intercept. Note: Because these transmitter bugs
inherently unstable, you better read the short legs of the components
keep the circuit mechanically tightly together up. Also placing a 1 nF
capacitor (C6) will benefit stability.
R1, R3, R4: 4K7
R2: 100K
R5: 10K
R6: 270 Ohms
C1, C2: 10 uF
C3, C6: 1 nF
C4: 2-18 pF trimmer
C5: 5.6 pF
L1, L2: air puddle windings on May 4 mm in diameter (see text)
T1, T2: 547 BC
Condenser microphone
Original Text:
Ook het plaatsen van een 1 nF condensatortje (C6) over de
voedingsaanluitingen komt de werking ten goede. [Origineel TinyCAD
ontwerp]
Show alternative translations
Posted on Friday, September 23, 2011 • Category: FM Transmitters
The circuit shown here is of a good Stereo
FM transmitter that can transmit high quality signals up to a range of
70 feet. The circuit is based on BH1417 PLL stereo transmitter IC from
Rhom semiconductors. The IC has separate audio processing sections for
the left and right channels, pre emphasis circuit for improving signal
to noise ratio, crystal control circuitry for accurate frequency
locking, multiplex circuit for making sum ( left plus right) and
difference ( left minus right) {see this article for better
understanding Stereo decoder circuit} etc. Another important feature of
this IC is that the transmission frequency can be set using a 4 channel
DIP switch. The IC can be powered from anything between 4 to 6V DC and
has an output power around 20mW. At full output power the circuit
consumes only 20mA and has a channel separation of 40dB.There are 14
possible preset transmission frequencies, starting from 88.7MHz and
incrementing in steps of 0.2MHz that can be selected using the DIP
switch. The PLL circuitry of the IC is so precise that there is
practically no frequency drift.
Posted on Thursday, August 25, 2011 • Category: FM Transmitters
This miniature transmitter is easy to
construct and it's transmissions can be picked up on any standard FM
receiver. It has a range of up to 1/4 of a mile or more. It is great for
room monitoring, baby listening, nature research, etc. L1 is 8 to 10
turns of 22 gauge hookup wire close wound around a non-conductive 1/4
inch diameter form, such as a pencil. C4 is a small, screw-adjustable,
trimmer capacitor. Set your FM receiver for a clear, blank space in the
lower end of the band. Then, with a non-conductive tool, adjust this
capacitor for the clearest reception. A little experimenting and
patience may be in order. Most of the parts' values are not critical, so
you can try adjusting them to see what happens.
Posted on Monday, August 8, 2011 • Category: FM Transmitters
Here is the circuit diagram of the simple FM
transmitter using a transistor. Great performance or range is not
guaranteed here, because this is an elementary design. General purpose
radio frequency transistor BF 494 (Q1) is used here for obtaining FM
modulation. A condenser mic is used here to pickup the sound.The
condenser mic converts the sound to electrical variations and this
variations are fed to the base of Q1 , which performs the amplification
as well as modulation.The capacitor C2 and L1 determines the
frequency of transmission.The circuit can be powered from a 9V
transistor radio battery.
Posted on Thursday, August 4, 2011 • Category: FM Transmitters
FM transmitter or often called fm
transmitter uses 2 transistors in this article uses 2 transistors
2n2222. If the fm transmitter is in use voltage supply of 9 volt battery
and use an antenna whose length is less than 12 inches, then this fm
transmitter will be within FCC limits.
Signals from the microphone in the fm transmitter is reinforced by Q1,
Q2 with carrier frequency generator is determined by the C5 and L1. The
frequency of the FM transmitter is in the range 80 MHz - 108 MHz. L1 can
be made with as many as 24 e-mail wire wrap and 6 wrap. The following
is a picture series for the fm transmitter fm transmitter referred to
in article 2 of this transistor.
Posted on Monday, August 1, 2011 • Category: FM Transmitters
If you want to be independent of the local
radio stations for testing VHF receivers, you need a frequency-modulated
oscillator that covers the range of 89.5 to 108 MHz — but building such
an oscillator using discrete components is not that easy. Maxim now has
available a series of five integrated oscillator building blocks in the
MAX260x series which cover the frequency range between 45 and 650 MHz.
The only other thing you need is a suitable external coil, dimensioned
for the midrange frequency.
Posted on Wednesday, July 27, 2011 • Category: FM Transmitters
A very good 1 watt fm transmitter circuit,
very easy to build circuit. It has 4 transistors, one is a very stable
oscillator, followed by a buffer stage to prevent frequency variation
when you adjust the transmitter. Next is a resonance stage and the final
stage built with a minimum 1W transistor which must have a heatsink.
You must use a LM7805 stabilizer for the oscillator diodes and one
LM7809 for powering up the T1 oscillator stage. This will give you a
very stable transmitter frequency.
Posted on Monday, July 18, 2011 • Category: FM Transmitters
This 2 Watt FM transmitter will provide 10km
range in good weather conditions. Use dipole antenna for maximum range.
Transmitter can be tuned between 88-108 MHz with c5. BB204 could be
replaced with conventional led (big) with reverse bias (no light given
in correct polarity). 9v power for 2km transmission with good sound
quality and up to 18v for 10km range. 2N3553 RF transistors may be
replaced with 2N4427 or 2N3866.
Posted on Friday, July 15, 2011 • Category: FM Transmitters
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. The layout of the 2SC1946 28 Watts FM broadcast RF
amplifier has been created with Eagle. The pcb outline is 100 x 50 mm
(width x height), all bitmaps have a resolution of 600dpi.Use FR-4
single sided photoresist epoxy pcb material for best results.
Posted on Thursday, July 14, 2011 • Category: FM Transmitters
This is a very simple 5 watt CW TX based
upon a TTL logic chip. There is just one "tricky" component and this is
Cx. This component should have an impedance of about 10 - 50 ohms at the
frequency of interest. If you wish to reduce the transmitter power,
increase the value of Cx. It is Cx which causes the square wave from the
output transistor to approximate a sine waveform. The value of Cx is
the price of simplicity in this TX.
Posted on Monday, July 11, 2011 • Category: FM Transmitters
This Wireless Microphone FM Transmitter has
been a very popular project with beginners and experienced constructors
alike. It has been used inside guitars and as the basis of a remote
control system. I do however, receive many requests for a higher powered
circuit and better microphone sensitivity. Now I can introduce the new
FM Wireless Microphone, which also has a better frequency stability,
over 1Km range (under ideal conditions) and is good on microphone
sensitivity. This has been achieved by adding an RF amplifier buffer
(with 10dB gain) and an AF preamplifier to boost the modulation a
little.
Posted on Friday, July 8, 2011 • Category: FM Transmitters
The transmitters on my homepage seem to be
quite popular, especially those intended for the 88 - 108MHz FM band. I
must really confess that I also favor this broadcast band, mainly
because it is so easy to find signals on the workshop radio. Everyone
has an FM radio, and it is fun to play with. Experimental antennas and
the like can all be developed in this band since there are a huge range
of "beacons" all transmitting just for my benefit :-). Basic oscillators
also are easy to fault-find in this frequency band, and then later
modified for other VHF bands.
The V5 FM Wireless Microphone is a 10mW transmitter that featured a coil
fabricated on the PCB itself. This made the project easy to duplicate
and removed "microphony" (the ability of coils to act as a microphone
with spring-line reverb). But as several people have already commented,
although more stable than most other similar kits and projects, the
frequency still does vary with battery voltage. In just one session it
can vary by 200kHz when a cheap "Mighty Atom" battery falls to 8 volts.
Posted on Thursday, July 7, 2011 • Category: FM Transmitters
Presented here is a Long Range FM
Transmitter. This circuit is a super-sensitive, mini-powered FM
transmitter consisting of a RF (radio Frequency) oscillator section
interfaced with a high sensitivity, wide pass-band audio amplifier and
capacitance mike with a built-in FET (Field Effect Transistor) that
modulates the base of the RF oscillator transistor. Transistor Q1 forms a
relatively stable RF oscillator whose frequency and is determined by
the value of coil L1 and turning capacitor C4.
Posted on Thursday, June 30, 2011 • Category: FM Transmitters
This is a 6m band transmitter RF power
amplifier (50 MHz) with 100W output. It used with my FT-736R and drive
from 10W for the 6m SSB DX. The Building information comes from Japan CQ
Magazine. The Toshiba RF bipolar power transistor is used in it.
If you want to construct this rf amplifier, it's the better way if the
double side PCB use for increase the grounding and current transfer. The
TX power can be tune to 120W.
Posted on Tuesday, June 28, 2011 • Category: FM Transmitters
Presented here is a 1.5 Watt FM Transmitter.
A transmitter is an installation in which electrical oscillations are
generated by an antenna as radio waves are emitted.Although there are a
variety of channels exist in terms of size, application and frequency,
each transmitter is an oscillator is present (usually crystal
controlled) that an electric thrill, the carrier, with a constant
frequency electricity.This is followed by one or more selective
amplifier stages tuned oscillation circuits, which usually frequency
multiplication is performed.Modulation can occur at low power, and even
strengthening of the modulated signal to the power required to
reach.Modulation can also occur at high power, when the carrier signal
and separately reinforced.
Posted on Thursday, June 23, 2011 • Category: FM Transmitters
Most transmitter has several variable
capacitors which are used to match impedance for transistors and
antennas. I know people hate trimmers and so did I. The reason is that
it is difficult to trim a system if you can't measure the performances.
To trim a transmitter you need to measure the output power.
Most transmitter are tuned with a dummy load of 50 ohm to substitute an
antenna of 50 ohm.
Not everyone has a power meter, and how can you know that the antenna
you connect is purely 50 ohm.
If not, the hole trimming is waste of time!
What you would like to do is to measure the radiated power out from the
antenna you actually are going to use.
If you can measure the radiated energy field you can easy tune the
system for max output field strength (max power).
So, how can we measure the radiated energy field?
The block diagram at right show you one easy way to measure the RF filed
strength. To the left you find a dipole antenna.
The antenna should be cut to match the receiving frequency ...
Posted on Wednesday, June 22, 2011 • Category: FM Transmitters
This is 80W RF power amplifier that boosts
FM Transmitter's power using 2SC2782 bipolar transistors in a tuned
class C circuit. RF amplifier can be driven to full 80W power with less
than 1 watt driving input power, so that a large gain margin results in
this FM transmitter.
To obtain stability in this RF amplifier, I employed several techniques,
such as placing the resonances of base and collector chokes far apart,
damping the chokes with resistors, using RC combinations for absorption
of unwanted frequencies, using feed trough capacitors for bypassing on
the board, etc. It took some tweaking, but the amplifier ended up
unconditionally stable.
Posted on Friday, June 17, 2011 • Category: FM Transmitters
RF Field Strength Meter with Attenuator up
to 200 MHz
The RF field meter unit is a great help to tune transmitters for best
performance and output power. You can measure the radiated energy field
and can easy tune the system for max output field strength maximum
power.
This field strength meter comes with selectable attenuator. You can use
it for measuring the antenna gain and pattern, compare different
magnetic field strengths. See the following RF field strength meter
schematic.
Posted on Friday, June 17, 2011 • Category: FM Transmitters
Here's 8W broadband FM RF amplifier using
2SC1971 VHF power transistor. The RF Amplifier PCB layout designed for
FM broadband 88-108 MHz transmitters using microstripline technique.
This 8W RF amplifier circuit provides an appropriate power boost for
transmitters with an input of 500 mW.
Posted on Tuesday, June 14, 2011 • Category: FM Transmitters
A very small home made FM transmitter Bug
using a single transistor and with a transmission range of 200 meters.
This FM transmitter Bug is very easy to build. The size of the circuit
board is ONLY 22mm x 10mm.
Posted on Saturday, June 11, 2011 • Category: FM Transmitters
Here's how to build a simple FM Transmitter.
This tiny transmitter has smaller radius of the service area, lower
quality of the sounds and the relatively unstable frequency. These can
be considered as a compromise to easily have your own transmitter for
the time being or as a more positive choice. These "defects" are only
from the perspective of conventional transmission such as "clear stereo
sound to receive anywhere". Artist could change these to another
directions. Whether or not, you can experience a convivial wireless
imagination by this transmitter.
Posted on Thursday, June 9, 2011 • Category: FM Transmitters
This micro spy PLL FM Transmitter transmits
on the 160MHz frequency (if we use a 40MHz quartz) and therefore can be
listened through a receiver tuned on this frequency. This circuit can be
used to on various frequencies, for example on the FM band 88-108 just
modifying some components, among which the quartz (25MHz).
Voice is detected by an electret microphone, then it is amplified and
filtered by U1 pass-band in order then to be modulated from the carrier
section, where through the varicap diode it "mixes" with the frequency
generated by the quartz, that guarantees an adapted stability.
Practically the modulating voltage is obtained applying the audio signal
to the resonating circuit varicap diode that determines the carrier
oscillation. The carrier frequency (160 MHz) must be greater than the
modulating frequency (300-3300 Hz) audio band.
The transmission is on the fourth harmonic, therefore 160MHz, the
oscillation frequency of the driver RF transistor Q1.
A small calibration is allowed acting on the L1 inductance and the C1
Trimmer Capacitor.
Posted on Wednesday, June 8, 2011 • Category: FM Transmitters
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,
problem-less, 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.
Posted on Friday, May 27, 2011 • Category: FM Transmitters
This is 8W PLL Stereo Transmitter with LCD.
It is a stable PLL FM transmitter based on TSA5511 synthesizer.
Frequency is performed with three buttons through PIC16F84
microcontroller. Frequency of the transmitter is displayed on 16x1 LCD.
Transmitter oscillator is based around BF981, BFR91, BFR96 transistors.
2SC1971 RF power transistor can be replaced with 2N4427 or 2N3553 but
they will provide less output power.
Posted on Friday, May 20, 2011 • Category: FM Transmitters
The power output of many transmitter
circuits are very low because no power amplifier stages are
incorporated. The transmitter circuit described here has an extra RF
power amplifier stage, after the oscillator stage, to raise the power
output to 200-250 milliwatts. With a good matching 50-ohm ground plane
antenna or multi-element Yagi antenna, this transmitter can provide
reasonably good signal strength up to a distance of about 2 kilometres.
The circuit built around transistor T1 (BF494) is a basic low-power
variable-frequency VHF oscillator. A varicap diode circuit is included
to change the frequency of the transmitter and to provide frequency
modulation by audio signals. The output of the oscillator is about 50
milliwatts. Transistor T2 (2N3866) forms a VHF-class A power amplifier.
It boosts the oscillator signal power four to five times. Thus, 200-250
milliwatts of power is generated at the collector of transistor T2.
Posted on Monday, May 9, 2011 • Category: FM Transmitters
This fm rf amplifier uses 2SC1971 transistor
to provide 5 watts of output. Output matching is adjusted via the two
40pF trimmer capacitors likewise also to the input. Note that the
emitter of this transistor is directly grounded on the heat sink and
should have a good thermal transfer. Driving power of 100 to 200mW can
be applied in order to provide 5watts of output. Use a dummy load to
tune this amplifier and remember that the transistor is biased in Class
C, sufficient filtering should be followed after the output to minimize
all the harmonics. Use ground plane construction technique in the PCB
lay-out for best result, the more the grounding the better. If you have
hard time finding the 10uH rf choke, try to wind 1/2 meter of 0.2mm
enamel wire over a 33K 1/2 watt resistor and solder the coil ends to
the legs of the resistor.
Posted on Monday, May 9, 2011 • Category: FM Transmitters
Presented here is a low-power FM transmitter
with varactor diode tuning using surface-mount devices (SMD) that will
be received with a standard FM radio. Soldering surface mounted devices
is not so hard and actually is quite easy. There are many designs for
small FM transmitters but they have some problems. First, you need an
audio amplifier to get enough modulation. Second, the antenna is
attached directly to the collector. Third, the coil L must be wound by
hand and adjusted by stretching. It all ads with a weak signal that
tends to drift in frequency. In contrast the transmitter schematic we
present here eliminates some of those problems, using varactor diode for
tuning and modulation, givin great sensitivity without an audio
amplifier.
Posted on Sunday, May 8, 2011 • Category: FM Transmitters
This particular transmitter was later
shipped up to VY1JA in the Yukon where, thanks to Jay's excellent
antenna system, it was heard in Europe as well as in New Zealand during
one of the Trans-Pacific Tests! Running 24 volts on the final will
produce 100 watts into a 50 ohm load.
The transmitter utilizes a 4060 binary counter IC chip as both the
crystal oscillator and frequency divider. I used a 2200 kHz crystal
along with the 'divide-by' sixteen output to produce a signal at 137.5
kHz. Other combinations of crystal frequencies and 'divide-by'
combinations may also be used since the 4060 features divided outputs
for f/32 (pin 5) and f/64 (pin 4), among others. You may have a 4MHz
crystal or an 8MHz crystal in your junk box that will put you in the
band using these output pins.
Posted on Thursday, April 28, 2011 • Category: FM Transmitters
This FM Wireless Microphone has been a very
popular project with beginners and experienced constructors alike. It
has been used inside guitars and as the basis of a remote control
system. I do however, receive many requests for a higher powered circuit
and better microphone sensitivity.
This High Power FM Wireless Microphone has a better frequency stability,
over 1 Km range and is good on microphone sensitivity. This has been
achieved by adding an RF amplifier buffer (with 10dB gain) and an AF
preamplifier to boost the modulation a little.
Posted on Thursday, April 28, 2011 • Category: FM Transmitters
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.
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.
One of the qualities of BA1404 FM transmitter is excellent frequency
stability. This is mainly due to a use of high quality 3.5 turn variable
coil. Tunable RF coils are ideal for precise frequency tuning because
their magnet wire is halfway embedded within the plastic, which
minimizes frequency drifts. Regular air coils are not preferred for
professional broadcasting because the coil expands and contracts with
temperature changes. That's the very reason why variable coil was chosen
as a substitution for an air coil and a variable capacitor.
Posted on Sunday, April 17, 2011 • Category: FM Transmitters
This small power FM transmitter can transmit
more than 1 km in good conditions. The modulation can be made so much
with a microphone or audio source. Circuit of power fm transmitter is
built around 2n2218 transistor. Transmitter coil is 5 turns of enameled
22 AWG wire, with diameter of 1 cm without nucleus. Look at the
capacitors that it should be ceramic. The antenna should possess from 15
to 40 cm. For transmission it ties a receiver of FM (radio) in the
proximity to half volume in a free frequency (that there is not any
radio operating), with a wood or plastic key, rotate the screw of CV to
capture the frequency of the transmitter.
Posted on Friday, April 15, 2011 • Category: FM Transmitters
This implementation is adapted to
rebroadcast the output of a CD player, television receiver, or radio
receiver. I use it so that I can move about the house and listen to my
favorite programs without disturbing others. Within and the house, I
find that I can get 10 to 20 meters away from the transmitter with the
small pocket FM receiver I carry in my shirt pocket. Your mileage may
vary. The transmitter as built and pictured below (the transmitter is in
the blob of hot melt glue on the end of the battery holder) does not
have an on-off switch. I put a 1.5 AA cell that was run down too far to
run my CD player in this transmitter and it ran for over a month before I
replaced it. The one in the transmitter at this moment has been running
it continuously for over three months. Current draw is only about a
milliamp with a new battery (assuming you don't have a super-high beta
transistor in which case the theoretical limit is about 2.5 ma). An
on-off swich is not necessary, though it may satisfy an emotional need.
Posted on Thursday, April 14, 2011 • Category: FM Transmitters
9 Volt battery operated simple Mini FM
Transmitter. FM Transmitter is very simple, compact, and has
transmission signal with a range of 100-150m, good sensitivity and low
current consumption. Transmitter's schematic consists of a bass
amplifier for the first transistor and the proper frequency generator in
the second. FM Transmitter divided transitional capacitor that allows
you to set up a cascade separately.
Posted on Tuesday, April 12, 2011 • Category: FM Transmitters
Here's a nice AC mains powered FM Broadcast
Audio Transmitter with pre-emphasis, audio level control, and tuning
control. The circuit consists of a frequency modulated oscillator, an
audio preamplifier with pre emphasis to supply the frequency modulating
signal, and a buffer amplifier to drive the antenna connector.
Oscillator's frequency is determined by L1 resonating with the 10 pf
capacitor and the total capacitance across it. The collector-base
capacitance of the transistors Q3, Q4, and Q5 is a function of their
revers bias. This is basically a poor man's (or lazy man's) varactor.
The voltage across Q3 is set by a voltage divider and is then modulated
by an Ac coupled audio signal from the pre amp, causing the reverse bias
to vary with the audio signal, which changes the resonant frequency of
L1's circuit, causing the frequency of the oscillator to vary with the
audio signal.
The capacitance of Q4 and Q5 is adjusted by DC bias from the tuning
adjustment potentiometer, and this capacitance sets the center frequency
of the oscillator.
All of the transistors in the oscillator -Q1 through Q5, are 2N4401.
The purpose of the buffer is to minimize frequency shift as loading on
the antenna is changed. It was specifically designed to reduce the
signal amplitude to the antenna. Transmitters should not use any more
power than is necessary to achieve the task at hand, and lightly
coupling the RF into the buffer's base with a gimmick capacitor did the
trick. The transistor is an MPSH34.
Posted on Saturday, April 9, 2011 • Category: FM Transmitters
Here's a tiny one transistor spy FM
transmitter bug that operates from a single 1.5V AA battery. Main
advantage of this circuit is that power supply is a 1.5 Volts 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
draws 1.4mA at 1.24V) which equals to 20 days. This way circuit
especially valuable in amateur spy operations. 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.
Posted on Thursday, April 7, 2011 • Category: FM Transmitters
This FM transmitter is about the simplest
and most basic FM transmitter it is possible to build and have a useful
transmitting range. It is surprisingly powerful despite its small
component count and 3V operating voltage. It will easily transmit over
300 meters in the open air and even more with higher voltage supply. The
circuit we use is based on a proven Australian design. It may be tuned
anywhere in the FM band. Or it may be tuned outside the commercial M
band for greater privacy. Of course this means you must modify your FM
radio to be able to receive the transmission or have a broad-band FM
receiver. The output power of FM transmitter is within the legal limits
of many countries. However, some countries may ban all wireless FM
transmitters without a license. It is your responsibility to check the
legal requirements for the operation and to obey them. FM transmitter is
constructed on a single-sided printed circuit board PCB.
Posted on Tuesday, April 5, 2011 • Category: FM Transmitters
Here's a PLL FM Transmitter using LMX1601,
ATtiny2313 or AT90S2313 microcontrollers. The common characteristic of
all of the previous low power FM transmitters I've built over the
decades, is that their operating frequency is determined by an LC
resonant circuit. Some of them had excellent stability, some of them
didn't, but I had always wanted to make one that is crystal controlled.
Various schemes had been considered from time-to-time, including the
direct approach of modulating the load capacitance of a a crystal
oscillator, a whimsical phase modulation scheme involving a phase
shifter, some balanced modulators, and limiting amplifiers, and at
times, the down-to-earth and sober approach of modulating a VCO within a
phase locked loop (PLL). While browsing Digikey's online catalog, I
found the LMX1601 frequency synthesizer chip and thought: "Just maybe,
the PLL approach is finally within my grasp."
The LMX1601, which apparently was designed for use in cell phones,
includes everything need to make two phase locked loops except for the
VCOs. More importantly, one of the PLLs, specifically the "AUX" PLL, is
specified to work in the FM broadcast band. The LMX1600 and the LMX1602
were also considered, but the LMX1601 was selected because it has a
"500 MHz option", meaning that it can work down to about 50 MHz.
Posted on Thursday, March 24, 2011 • Category: FM Transmitters
The FM telephone circuit is built on a PC
board that is so small it can easily be fitted inside the housing of a
telephone making it an instant pseudo-speak earphone. This FM
transmitter circuit connects in series with telephone line, steals power
from it, and transmits both sides of the conversation to an FM radio
tuned between 90 and 95 MHz.
Posted on Friday, March 18, 2011 • Category: FM Transmitters
Circuit of stereo FM transmitter of of high
quality using integrated circuit ba1404 for mp3, mp4, ipod, computer,
radio of the car. Transmit of your equipment of portable audio for the
radio of your car, transmitters of fm of low potency are the ideal for
transmission wireless of audio sign for fm receivers. Mainly in that
case that is treated of transmitter of FM stereo with ba1404.
The heart of that circuit is the circuit integrated ba1404, that is a
mini fm transmitter, that already counts with the necessary internal
circuits for transmission in fm. just being necessary to increase some
components discman or any other audio source turning the wireless. If
you already set up other transmitters of transistorized fm it will see
that when setting up that with having integrated BA1404, that the
quality of the sound and the frequency stability is excellent. Besides
the but it presents easy assembly.
Posted on Friday, March 4, 2011 • Category: FM Transmitters
The goal of this project is for me
personally to learn a little more about fm transmitters and fm bug
making (may the HAM radio gods bless me in this pursuit). The ideal
outcome of this project is a very small and full functional FM
transmitter that we can stick into a plastic mint box.
In order to be able to build this, we'll have to learn a lot
about amplifiers, LC oscillators, mixers, antennas and FM. This project
assumes you're already comfortable build your own PCB boards. If you're
not please take a look at the homemade pcb's tutorial before you
continue. It will help you out a lot.
Posted on Sunday, January 30, 2011 • Category: FM Transmitters
So, I needed a small transmitter, which
would allow me to transmit good, old music into my AM-only radios. So,
one saturday afternoon I got into gear, designed and built a very crude,
terribly non-optimized little transmitter. It's almost a joke expressed
in electronics, full of poor design, so please don't think that this is
the best I can do! You must see it as a quick and dirty 5-hour effort,
because that's all the time the transmitter took to design, build, and
test. Making this web page about it is taking much longer! I'm putting
this thing on the web only because many people have asked me to do so,
despite its crude design!
Posted on Saturday, January 29, 2011 • Category: FM Transmitters
This unit is an updated version of the Wide
Dynamic Range Field Strength Meter. While the basic function is the
same, it has several critical differences:
It uses a specialized integrated circuit, the Analog Devices AD8307.
This chip is designed specifically as a logarithmic amplifier for use
through 500 MHz.
Using the AD8307, it has a wider dynamic range (85 dB versus 55 dB) and
it has built-in temperature compensation.
Because of the different nature of this type of detector - and the fact
that it has temperature compensation - means that there is no need for a
"zeroing" control.
One disadvantage of this approach as compared to the diode approach is
that the AD8307 has a lower frequency response than the diode. The
frequency limit of the meter is dictated pretty much by the diodes
themselves along with their physical layout and related components:
There is no reason why the earlier version could not be constructed to
work through 10 GHz or so - but the AD8307 is falling flat by the time
you get to 1 GHz, making it unsuitable for detecting wireless LANs or
PCS-type cell phones.
Posted on Thursday, January 27, 2011 • Category: FM Transmitters
Everyone involved with radio transmitters
needs some instruments to assess basic antenna functionality. Among
these instruments, the best-known and most-used one is the Standing Wave
Ratio meter. Some radio amateurs develop a cult for these little
gadgets, having them in line all the time and watching the needles
bounce while they chat. I have seen some guys owning 5 or 6 SWR meters,
and no other instrument relating to antenna testing! While it's
unfortunate that some people - specially amateurs - assign so much
importance to SWR and so little to other parameters, it's also a fact
that SWR needs to be known, so if you use transmitters, you need an SWR
meter.
Posted on Wednesday, January 26, 2011 • Category: FM Transmitters
Be "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. Add 500mW FM / VHF Transmitter Amplifier / Booster
for 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.
Posted on Wednesday, December 29, 2010 • Category: FM Transmitters
This small FM transmitter with a range of
about 50 meters designed for connection to the USB port. With lots of
mini-transmitters then you have a comprehensive, action-packed radio
program. Due to the power supply via the USB port of a high frequency
stability is achieved. Alternatively, the receiver, a battery 5 to 12
volts to operate.
Posted on Wednesday, December 29, 2010 • Category: FM Transmitters
Easy to build high-quality PLL FM
transmitter with typical output power of 5 W and no-tune design. The
transmitter includes RDS/SCA input and Audio/MPX input with optional
pre-emphasis. It can be used with or without stereo encoder. Tuning over
the FM band is provided by two buttons that control dual-speed PLL. The
transmitter can work also without the LCD display. Some experience with
building devices of this kind are highly recommended.
Posted on Saturday, October 16, 2010 • Category: FM Transmitters
This circuit is a circuit diagram fm
transmitter. This circuit is somewhat different from the previous fm
transmitter circuit. Transmitter circuit described here has the
additional RF power amplifier stage, after the oscillator stage, to
increase the power output of 200-250 milliwatts. With a good matching
50-ohm ground plane antenna or multi-element yagi antenna, this
transmitter can provide a good enough signal strength to a distance of
about 2 kilometers.
Posted on Thursday, October 7, 2010 • Category: FM Transmitters
Posted on Thursday, October 7, 2010 • Category: FM Transmitters
Simple oscillator that generates a frequency
in the VHF or UHF region. The oscillator is modulated with the video
signal and the modulated carrier wave thus generated is fed into the TV
set's aerial input via a cable. Then all that remains to do is tune the
TV to the correct frequency.
Posted on Thursday, October 7, 2010 • Category: FM Transmitters
This handy prescaler divides input frequency
by 1000. It takes maximum input frequency of 3.5GHz and converts it
into 3.5MHz that may be measured using standard frequency meter.
Posted on Wednesday, October 6, 2010 • Category: FM Transmitters
RF amplifier with 25W of power for 88-108MHz FM transmitters.
Posted on Wednesday, October 6, 2010 • Category: FM Transmitters
The important part of the circuit is formed
of the Colpitts type oscillator. C3,C4,C5,C6,CD1-CD2 and L1 determines
the frequency. BF982 and dual gate MOSFET are active parts in
oscillator. When the input impedance of the MOSFET gate inputs are high,
LC tank is not affected. However transistors force the LC tank and
cause phase shift. Two driver stages are added to isolate the antenna
from oscillator. First stage (BF199) amplifies the low signal of the
oscillator and works as a constant load. The second stage (BFR90)
amplifies the signal going through the antenna some more. A short copper
wire can be used as an antenna here. Attaching a large antenna to this
circuit is unnecessary because the output power is low.
Posted on Wednesday, October 6, 2010 • Category: FM Transmitters
Here is a simple set up which will enable
them to measure the out put power of their transmitter. All that they
require is a good multimeter which has a sensitivity of 20k ohms/4 Watts
which is adequate for low power transmitters. Many beginners trying out
their skill with QRP TX, for the first time have to overcome many
problems before they are able to come on the air. On usual complaint is
that, every thing is working fine but the signal is not going out.
Posted on Wednesday, October 6, 2010 • Category: FM Transmitters
This FM transmitter attaches in series to
one of your phone lines. When there is a signal on the line (that is,
when you pick up the handset) the circuit will transmit the
conversation. In particular it will radiate from the phone line itself.
It is a passive device - there is no battery. It uses the signal on the
phone line for power. No aerial is needed - it feeds back the RF signal
into the phone line which radiates it in the FM band. The frequency of
transmission may be adjusted by the trimcap.
Posted on Tuesday, October 5, 2010 • Category: FM Transmitters
The PLL transmitter exciter has the
functions of providing a stable, low noise, frequency-selectable RF
signal and amplify it to a controllable output power sufficient to drive
the power amplifier. It uses a PLL frequency synthesizer built with
MC145151, which covers the FM band in 100kHz steps. The VCO covers only a
few MHz without readjustment.
Posted on Tuesday, October 5, 2010 • Category: FM Transmitters
The 30 watt amplifier schematic shown below
provides an appropriate power boost with an input of 4 watt up to 6
watts. The circuit is designed to cover 88-108MHz FM Broadcast Band.
However, the circuit is very stable at my place and provides a
clean-output through seven (7) element Butter-worth low-pass filter.
Posted on Tuesday, October 5, 2010 • Category: FM Transmitters
Presented is a three stage 3W FM Transmitter
Amplifier using 2SC9018, 2SC2053 and 2SC1970 transistors. The circuit
is supplied by 12-14V DC voltage and requires at least 500mA of current.
Posted on Tuesday, October 5, 2010 • Category: FM Transmitters
One of the most useful gadgets a video
enthusiast can have is a low-power TV Transmitter. Such a device can
transmit a signal from a VCR to any TV in a home or backyard. Imagine
the convenience of being able to sit by the pool watching your favorite
movie on a portable with a tape or laser disc playing indoors. You could
even retransmit cable TV for your own private viewing.
Posted on Wednesday, September 15, 2010 • Category: FM Transmitters
A amplifier of medium force RF for the FM,
is always essential for the amateur that wants it strengthens some small
transmitter, that likely it has already it manufactured! The present
circuit can give force 25-30W, with control no bigger than 4-5 W.
As it appears in the analytic drawing, the amplifier is manufactured
with the transistor TR1 of type LY89 of Phillips. The transistor this is
specifically drawn for operation in frequencies up to 175Mhz, with very
good results.
Posted on Tuesday, September 14, 2010 • Category: FM Transmitters
This project is a simple 2-transistor VHF
power amplifier, with about 16dB gain, and requires no tuning or
alignment procedures. Wideband techniques have been used in the design
and the circuit is equipped with a "lowpass" filter to ensure good
output spectral purity. The project has been designed for assembly on a
single-sided printed circuit board. The circuit is specifically designed
to amplify the output of 7mW to 10mW WBFM transmitters (wide band) to a
final level of 250mW to 300mW.
Posted on Friday, September 3, 2010 • Category: FM Transmitters
5W PLL Stereo FM Transmitter features PLL
synthesized drift free operation with high quality BH1415 chip. 5W RF
output power is achieved with 2SC1971 6W transistor in the output stage.
Front panel digital control comes with LED display and case is made
high quality aluminum. The board features EMI filtering on audio and
power inputs and comes with Microphone and Audio inputs. Once
transmitter is turned on it starts broadcasting with previously selected
frequency. Overall this 5W PLL Stereo FM Transmitter provides
professional broadcast audio quality and rivals commercial broadcasts.
Posted on Friday, September 3, 2010 • Category: FM Transmitters
This is a unique FM transmitter that
provides both a built-in sensitive microphone and an RCA jack for line
input. It has two modes of operations, "Microphone" and "Line", which
are selectable using a jumper. In the "Microphone" mode, it can be used
as a wireless microphone transmitter. In the "Line" mode, it can be
easily connected to any audio source to broadcast the audio signal to
any FM receiver within its range. 500mW FM / VHF Transmitter Amplifier /
Booster can be added for longer transmission range.
Posted on Friday, September 3, 2010 • Category: FM Transmitters
Features PLL tuned transmitter / exciter for
rock solid frequency stability over the entire FM band. Displays
Transmitted Frequency on backlighted LCD. PCB includes antenna output to
which a piece of wire, or VHF amplifier can be connected for greater
transmission range. Includes 3.5mm audio jack cable. Plays MP3 from SD
and USB memory (SD and USB connectors on board). IR Remote can be used
to control the transmitter.
Posted on Friday, September 3, 2010 • Category: FM Transmitters
This is a high quality stereo PLL FM
transmitter incorporating a Phase-Locked-Loop (PLL) synthesizer. It is
based on the Rohm BA1417 PLL FM Transmitter Integrated Circuit and
offers a choice of up to 14 preset transmission frequencies spaced every
200 KHz between: 88.7 – 88.9 MHz (Low Band Mode) and 106.7 – 107.9 MHz
(High Band Mode). It has outstanding frequency stability thanks to the
PLL crystal controlled design and offers excellent high-fidelity audio
performance.
It is ideal for use in your home or office to transmit MP3 songs or
internet radio stations from your computer to any standard FM radio. It
can also be connected to any other audio source, such as an iPod, a MP3
Player, Walkman, Discman or XM Satelite Radio receiver.
The circuit incorporates a stereo audio input jack as well as a DC
adapter jack which makes it quick and easy to setup. Transmission
frequency selection is done through a DIP switch.
Posted on Thursday, August 5, 2010 • Category: FM Transmitters
This is an excellent 50mW Hi-Fi PLL FM
Stereo Transmitter that features BH1417 chip. ROHM's new Japan has
BH1417 is one of the most simple and practical integrated circuits,
which combines phase-locked loop circuit, stereo encoder circuit,
transmitter circuit, as well as other additions. Pre-emphasis circuit,
limiter circuit and low pass filter can significantly improve the sound
quality. The total harmonic distortion up 0.3%, stereo separation to
40dB, RF output level is 100dB. BH1417F is an excellent new IC chip,
this circuit improves signal to noise ratio (S / N) of pre-emphasis
circuit to prevent signal over emphasized limiting circuit, the control
input signal frequency low-pass filter circuit (LPF), generate stereo
stereo composite signal modulation circuit, FM transmitter phase-locked
loop circuit (PLL) component. BH1417F excellent frequency
characteristics, it can achieve 40dB of isolation, transmitted sound
quality is similar to local FM radio stations.
Posted on Thursday, August 5, 2010 • Category: FM Transmitters
5W PLL Stereo FM Transmitter features PLL
synthesized drift free operation with high quality BH1415 chip. 5W RF
output power is achieved with 2SC1971 6W transistor in the output stage.
Front panel digital control comes with LED display and case is made
high quality aluminum. The board features EMI filtering on audio and
power inputs and comes with Microphone and Audio inputs. Once
transmitter is turned on it starts broadcasting with previously selected
frequency. Overall this 5W PLL Stereo FM Transmitter provides
professional broadcast audio quality and rivals commercial broadcasts.
Posted on Thursday, July 15, 2010 • Category: FM Transmitters
This Phone FM transmitter connects in series
to your telephone line and transmits the telephone conversation over
the FM band when you pick up the telephone handset. Transmitted signal
can be tuned by any FM receiver. The circuit includes an "On Air" LED
indicator and also provides a switch which can be used to turn off the
transmitter. A unique feature of the circuit is that no battery is
needed to operate the circuit since power is taken from the telephone
line. The transmitter uses only a short piece of wire aerial about 4" /
10 cm long to transmit the signal and some of the RF signal is also
radiated through the telephone line itself. The circuit might be used to
share or record conversations, but is not intended for illegal use.
Posted on Thursday, July 8, 2010 • Category: FM Transmitters
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.
Posted on Saturday, June 12, 2010 • Category: FM Transmitters
This small FM transmitter includes a
limiter, a microphone amplifier and a PLL digital tuning. All the parts
are placed on one circuit board. The RF power is switchable between 1W
and 0,2W.
The schematic diagram is divided into three parts: RF part (numbered
from 1), PLL (numbered from 30) and audio part (numbered from 50).
Posted on Saturday, June 12, 2010 • Category: FM Transmitters
The TX500 is a simple to build 500mW FM
Transmitter. It consists of three blocks; modulator / oscillator, two
stage 500mW VHF amplifier and LED based power meter. The TX500 allows to
transmit audio signals to FM band at frequencies from 88 MHz to 108
MHz. Due to the very low power consumption of less than 100mA the
circuit may be perfectly powered by using 9-12V battery or power supply
if you prefer. The circuit has been divided into separate stages so that
it is be better for everyone to understand how every part works
independently.
Posted on Saturday, June 12, 2010 • Category: FM Transmitters
BH1417 is a latest FM Transmitter IC 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.
Posted on Saturday, May 22, 2010 • Category: FM Transmitters
This FM transmitter circuit uses four radio
frequency stages: a VHF oscillator built around transistor BF494 (T1), a
preamplifier built around transistor BF200 (T2), a driver built around
transistor 2N2219 (T3) and a power amplifier built around transistor
2N3866 (T4). A condenser microphone is connected at the input of the
oscillator.
Posted on Thursday, May 6, 2010 • Category: FM Transmitters
This page describes TX ATV Transmitter for 23 cm with output adjustable from 100 to 250mW.
Posted on Friday, April 30, 2010 • Category: FM Transmitters
This new FM transmitter is very simple and
doesn't need any RF tuning.
First of all ,we have used an integrated VCO: The POS150 from
Mini-circuits.
This excellent RF circuit covers all the FM Band in a voltage range of
4V to 8V.
The Kvco factor is very stable all over the FM band, consequently, we
have applied the BF signal directly on the control voltage line coming
from the PLL.
Posted on Friday, April 30, 2010 • Category: FM Transmitters
The functioning of all is provided by a
microcontroller from MICROCHIP "PIC16F84" which provides support for
buttons, LCD 2 lines of 16 characters and the circuit pll "SAA1057.
The VCO is entrusted to the transistor Q8 associate of his two diodes
varicaps "BB109, a floor buffer Q7 separates the VHF signal obtained in
two ways, on the one hand to Q9 to enslave loop phase and on the other
hand to the Q5 and Q6 together which takes care to amplify the signal
before attacking Q11, a "BFR96" which plays the role of HF switch via a
timer "NE555" which receives information from the push and "SAA1057"
ensuring HF cutoff in the event of failure of a locking or unlocking of
the pll.
Posted on Friday, April 30, 2010 • Category: FM Transmitters
Filter used for eliminate unwanted harmonic
frequency at second and third. Notch filter, Band Pass Filter (BPF), and
High Pass Filter (HPF) sometime combined in constructing LPF design.
Schematic below for FM Broadcast Lowpass Filter 88-108 MHz. It has been
tested with a good result.
Note : Make the coils at 74 nH and trim them to adjust exact value.
Posted on Thursday, April 29, 2010 • Category: FM Transmitters
In order to simplify the transmitter design, we've used the new pll circuit from Motorola :the MC145170.
This PLL includes the prescaler and a serial standard bus called SPI.
Posted on Wednesday, April 28, 2010 • Category: FM Transmitters
This map, armored also enables automatic
MONO / MPX through a low-pass filter, even with a multiplex on its entry
by using an ON / ON, panning, the whole spectrum MPX more RDS is sent
to the synthesizer, on the other hand when it is in a position MONO, the
low-pass filter is activated and share its cutoff frequency at 15 KHz,
only modulation G + D is sent to the synthesizer, as 19 KHz. 19 KHz
carrier, the signal multiplex and subcarrier 57 KHz is thereby
eliminated, which provides ease of use for example in a string of issue
relay tuner, if the link between the issuer Departure and receiver
re-issue was not of good quality stereo, you sufficient to switch to
mono to improve sound quality, you can then connect the RDS encoder at
the re-issuer.
Posted on Friday, April 23, 2010 • Category: FM Transmitters
This PLL has been designed with an old Motorola circuit :the MC145151.
The VCO is based on a "Colpitz" oscillator equiped with a Fet Transistor.(J310)
Two varicap Diodes are used in order to reduce the global noise of the VCO.
In addition,these two diodes allow the PLL to keep the lock status through a large range of climatic conditions.
An another J310 is used in order to match the impedance between the oscillator and the fist amplifier stage.
A MSA1105 from Minicircuits increases the RF power level coming from the VCO to +14dBm.
A simple low pass filter rejects the second harmonic to -20 dB.(Worst case)
Finally, a 7 dB attenuator and a second amplifier stage (BFR96S) achieve this radio design.
Posted on Friday, April 23, 2010 • Category: FM Transmitters
This is a universal 1 Watt RF class C
amplifier that is ideally suited for low power FM transmitters. Input
should be at least 100mW to achieve 1W output. It is recommended to
enclose the amplifier in a metal case.
Posted on Thursday, April 22, 2010 • Category: FM Transmitters
This page describes TX ATV Transmitter for 23 cm with output adjustable from 100 to 250mW.
Posted on Saturday, April 10, 2010 • Category: FM Transmitters
This is a PLL controller that works with the
VCO/Modulator that I designed. Use these two modules together for a
complete baseband-capable exciter unit. This PLL controller features a
rock-stable crystal controlled reference, in conjunction with a
programmable dividing network which allows the transmitter to be tuned
in 100Khz steps from 79.9Mhz to 109.7Mhz by means of digital thumbwheel
switches. Oscillator, buffer and driver stages use 2N3866 power RF
transistor and output stage used 2N3553 4W RF transistor,
Posted on Friday, February 19, 2010 • Category: FM Transmitters
This MP3 Player FM transmitter can be used
to listen to your own music throughout your home. The transmitter
circuit use no coils that have to be wound. 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. 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. The supply voltage to the IC should be between 2.7
and 5.5 V, the current consumption is between 2 and 4 mA.
Posted on Friday, February 19, 2010 • Category: FM Transmitters
This 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.
Posted on Friday, February 19, 2010 • Category: FM Transmitters
This design is a 2 stage amplifier that has
about 17db of gain, suitable for an input of 50 to 100 MW. Its basically
a Veronica 5 watt vco transmitter, without the vco. The transistors are
a 2N4427 and a MRF237. Output power is 2.5 to 5 watts, depending on
input drive and dc voltage. At 13.7 vdc with 50 MW of drive, the output
was 2.5 watts. The maximum dc voltage recommended is about 15-16 volts.
Posted on Saturday, October 31, 2009 • Category: FM Transmitters
The transmitter uses 2 MPSH10 (equiv BF494
or NTE229) transistors in a double-ended free-running voltage controlled
oscillator (VCO) operating at half the output frequency on each side
and combined at L2, which is tuned to the 2nd harmonic of the VCO and
covers the 88-108 MHz range. A standard 9 volt battery is used for power
and fits inside the tin. The mono audio input circuit is totally
passive with 70us pre-emphasis provided and the audio quality is great.
Posted on Thursday, October 29, 2009 • Category: FM Transmitters
This is a 1 watt amplifier. This design is a
2 stage amplifier that has about 16db of gain, suitable for an input of
5 to 20 MW. The transistors are a 2N4401 and a 2N4427. At 13.7 vdc the
most I could get out of the unit was 1/2 watt, you could probably raise
the dc voltage to 16 volts and get more output but then a much better
heatsink would be required. But for the sake of this project, we'll call
it a 1/2 watt amplifier.
Posted on Tuesday, October 27, 2009 • Category: FM Transmitters
The achievement of this 30-watt amplifier
has been designed to take place on a heatsink microprocessor PC equipped
with its fans, the advantage of this method of cooling has been
selected for the fact that it is not very common and expensive. The size
of the printed circuit will adapt quite easily to the type of heatsink
as you have available, if possible, because in many cases, those of
recovery, the fans have already lived and the price of a model remains
very affordable.
Posted on Tuesday, October 27, 2009 • Category: FM Transmitters
This Power amplifier is equipped with a
bipolar transistor,the famous MRF317 As lots of FM amplifier application
,the power transistor is in a C class bias. All the impedance networks
(Input & Output) have been determined by using the software:
Mimp.EXE. A 9 elements low pass filter ensures that we meet at least a
60 dB rejection from the carrier.(RF Simulation with RFSIM99) The FM
amplifier has a 10 dB gain with a 60 to 65% efficiency. The Input VSWR
is around 1.4 and there's no problem to reach the max power in all the
FM band.
Posted on Tuesday, October 27, 2009 • Category: FM Transmitters
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.
Posted on Tuesday, October 27, 2009 • Category: FM Transmitters
That RF Amplifier is for boosting small fm
transmitters and bugs. It use two Philips 2N4427 and its power is about
1Watt. At the output you can drive any linear with BGY133 or BLY87 and
so on. Its power supply has to give 500mA current at 12 Volts. More
voltage can boost the distance but the transistors will be burned much
earlier than usual.! In any case do not exceed the 15Volts. The Amp
offers 15 dB in the area of 80Mhz to 110 Mhz. L4, L5, and L6 are 5mm
diameter air coils, 8 turns, with wire 1mm wire diameter.An easy
project, with great results.
Posted on Saturday, August 22, 2009 • Category: FM Transmitters
This watt meter project is very similar to
my last wattmeter project. The main reason I made a new project is
becasue I needed a unit which could handle higher power than 1W. I found
a 50 ohm dummy load which could take 50W of power. Of course I could
use attenuates for my 1W meter, but I prefered to build a new unit. The
new thing with this project is that it will only display the power in
Watt on the LCD display.
Posted on Monday, November 10, 2008 • Category: FM Transmitters
Here is a stereo FM Transmitter based on
BH1415F wireless audio link IC. Phase Locked Loop controller use
Microchip PIC16F628 and the the PLL frequency programming can be
displayed with 8×2 and 16×2 LCD display. The frequency range can
adjustable from 88-108 MHz.
Posted on Monday, November 10, 2008 • Category: FM Transmitters
This is FM PLL Stereo based BH1415F IC from
Rohm, it's has built in PLL and Stereo Encoder. You can download the
schematic, pcb layout and Hex code. The transmitter menu display with
LCD, and this have step 100Khz, 200Khz,.....1000Khz and have Mode menu
(stereo/mono). In Action, LCD Display can solder directly on the bottom.
Posted on Tuesday, May 6, 2008 • Category: FM Transmitters
This is a high quality PLL Stereo FM
Transmitter with build-in VHF amplifier for longer transmission range.
It is based on BH1417 chip that offers high quality crystal clear stereo
transmission. Eight available frequencies are controlled by grounding
S1, S2 and S3 pins on header connector. Includes, high quality ROHM
BH1417 transmitter chip, on-board amplifier increases transmission
range, uses 7.6MHz crystal for rock-solid PLL FM transmission, crystal
based Stereo Encoder and 3.5 standard audio input jack.
Posted on Thursday, April 24, 2008 • Category: FM Transmitters
Many people prefer to listen to their own music (or voice) on radio.
This project explain how you can build and connect a powerful 1W amplifier to your FM transmitters.
A perfect solution for those wishing to listen to their favorite tunes in the car, house, garden,
school, campus, party, you name it....
Why not share your music with every one else in your city!
Posted on Thursday, April 24, 2008 • Category: FM Transmitters
BH1415F FM Stereo PLL Transmitter
Transmitter power amplifier, the output signal from BH1415F by 2 SC9018,
2SC3355, 2SC2053 amplified signal can reach more than 500 mW, adjusting
well to achieve greater power. Measured by the pull rod antenna used to
be launched in the open 800 meters above. Uses external antenna will be
launched even further. attention in 2053 need to be installed and
tested at the load connected to leave, or else very easily burn 2053, 50
European amateur production of 2 W can be used instead of resistance.
installed and tested at three levels circuit can be installed and
tested.
Posted on Wednesday, April 23, 2008 • Category: FM Transmitters
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.
Posted on Sunday, April 20, 2008 • Category: FM Transmitters
Now you can use your MP3 Player to listen
your favorite tunes through any FM stereo receiver. Wireless FM
transmitter wirelessly connects portable music players to your car or
home stereo quickly and easily. Just plug the FM Transmitter into the
headphone jack of your MP3 or any audio source including iPOD, PDA, CD
Player, Cassette player or connect it to your PC or laptop computer.
Tune your card stereo or receiver to the clearest FM frequency, and
enjoy your digital music with full sound and convenience.
Features:
- PLL tuned transmitter / exciter for rock solid frequency stability
over the entire FM band
- Displays Transmitted Frequency on blue backlighted LCD
- 100KHz frequency increments
- Includes three frequency memory buttons
- PCB includes antenna output to which a piece of wire, or standard VHF
amplifier can be connected for greater transmission range
- Uses PLL synthesizer chip up to 1.4GHz
- Includes 3.5mm audio jack cable
- Small size
Posted on Tuesday, April 15, 2008 • Category: FM Transmitters
This is a high quality PLL Stereo FM
Transmitter with build-in VHF amplifier for long transmission range. It
is based on BH1417 chip that offers high quality crystal clear stereo
transmission. Eight available frequencies are controlled by grounding 3
pins on header connector. This transmitter comes assembled and is ready
to use.
Features:
- Two on-board transistors increase transmission range
- Uses 7.6MHz crystal for rock-solid PLL FM transmission
- Crystal based stereo encoder
- Very small size
Posted on Monday, April 14, 2008 • Category: FM Transmitters
Here 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.
Posted on Thursday, April 10, 2008 • Category: FM Transmitters
This project will explain the basic function
of a class-C transmitter. I will explain how to dimension a transmitter
and the purpose of the different components. I will also explain how
you can build a 1.5W PA transmitter. The project will include PCB,
components and instructions how to make coils, assembly and testing.
Posted on Thursday, April 10, 2008 • Category: FM Transmitters
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.
Posted on Tuesday, April 8, 2008 • Category: FM Transmitters
Very stable FM transmitter based on TSA5511
synthesizer. Frequency is performed with three buttons through PIC16F84
microcontroller. Frequency is displayed on 16×1 LCD.
Posted on Wednesday, April 2, 2008 • Category: FM Transmitters
Be "On Air" with your own radio station!
BA1404 based transmitter is an exciting product that will broadcast a
high quality stereo signal in the 88 – 108MHz FM band. It can be
connected to any type of stereo audio source such as personal computer,
CD player, Walkman, television, tape deck or stereo system to transmit
stereo sound with excellent clarity throughout your home, office, yard
or camp ground.
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