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Sensitive FM Transmitter Bug - 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. __
Short Wave AM Transmitter - The main feature of this transmitter is that it is free from the LC (inductor, capacitor) tuned circuit and operates on a fixed frequency of 12 MHz which is extremely stable.___ Electronics Projects for You
Shortwave Audion - It is a Hartley-ECO Audion, in which the plate is grounded for RF. Positive feedback from cathode to grid occurs via the coil tap. The amount of feedback is determined by the 100k pot; this controls the voltage at the screen grid and thereby the transconductance of the valve (higher voltage resulting in greater transconductance). __
Shortwave Bug - Circuit and notes only, no circuit description given. __ Designed by Tony van Roon VA3AVR
Simple AM Radio Receiver - This circuit is essentially an amplified crystal set. The inductor could be a standard AM radio ferrite rod antenna while the tuning capacitor is a variable plastic dielectric gang, intended for small AM radios. The aerial tuned circuit feeds diode D1 which functions as the detector. A germanium type is far preferable to a silicon __
Simple Circuit AM Transmitter - There are not many AM transmitters that are easier to build than this one because the inductor is not tapped and has a single winding. There is no need to wind the inductor as it is a readily available RF choke. To make the circuit as small as possible, the conventional tuning capacitor has been dispensed with and fixed 220pF capacitors used instead. To tune it to a particular frequency, reduce one or both of the 220pF capacitors to raise the frequency or add capacitance in parallel to lower the frequency. Q1 is biased with a 1MO resistor to give a high input impedance and this allows the use of a crystal ear piece as a low cost microphone. __
Simple Circuit Audio FM Transmitter - FM transmitters can be complicated to build, but not this one it’s about the easiest you can possibly make. And though the science of radio is well understood, there’s a magical, emotional quality about it that we don’t often stop to appreciate. You will not forget the first time you pick up a transmission broadcast from a device you soldered together, yourself, from a few bits of copper, carbon, plastic, and wire. __
Simple Circuit Coil Less FM Transmitter - 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!). __
Simple Circuit FM Exciter - I have had requests to add a VHF FM transmitter, to the QRP collection. This project is a simple 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 __ Designed by Harry Lythall-SM0VPO
Simple Circuit FM Receiver - With the TDA 7000 you can build an FM radio with a minimum of components; most of them so easy to managelike the ceramic capacitors that do not require polarizationand only two resistors. The components you will employ will be of small dimensions and low cost. Even the integrated circuit itself, the TDA 7000, is not of great cost. __
Simple Circuit FM Stereo Transmitter - (ATTINY12, ATTINY25, ATtiny2313, AT90S2313, AT90S232, or nearly any other CMOS microntroller-Yes probably even a PIC!) This project appeared in the December, 2007 issue ofInfo Elektronika Magazine __ Designed by © Richard Cappels
Simple Circuit FM Transmitter - Simple FM transmitter with a single transistor. MinI FM transmitters take place as one of the standard circuit types in an amateur electronics fan's beginning steps. When done right, they provide very clear wireless sound transmission through an ordinary FM radio over a remarkable distance. I've seen lots of designs through the years, some of them were so simple, some of them were powerful, some of them were hard to build etc. __
Simple Circuit FM Transmitter Bug - 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 __
Simple Circuit FM Transmitter with a Single Transistor - MinI FM transmitters take place as one of the standard circuit types in an amateur electronics fan's beginning steps. When done right, they provide very clear wireless sound transmission through an ordinary FM radio over a remarkable distance. I've seen lots of designs through the years, some of them were so simple, some of them were powerful, some of them were hard to build etc. __ Designed by Kamran Ahmed-UK
Simple Circuit FM Transmitter with BC549 - This is simple FM transmitter for FM broadcast band in 88-108 MHz. BC 549 is small signal transistor for wide applications, but usually for AF. You can build simple FM transmitter with one BC549 transistor and several other component parts. Simple FM transmitter with only one transistor is often called “bug”. This project is suitable for beginners in radio amateur, education, or hobbies. As an antenna you can connect 150cm of copper wire. __
Simple Circuit FSK Modulator - 10/11/01 EDN Design Ideas: The need for a compact telemetry system poses a challenge for designing a small, light, low-component-count system. Interfacing serial data from the microprocessor is also difficult because most low-cost RF transmitters do not accept dc levels at the input. Commercial FSK (frequency-shift-keying] modulators are bulky and need many passive components Design by Shyam Tiwari, Sensors Technology Ltd, Gwalior, India
Simple Circuit FSK Modulator Enables Data Transmission Over Low-Speed Link - 06/11/09 EDN Design Ideas: Send digital data over a low-speed link. FSK (frequency-shift keying) is a type of signal modulation for transmitting digital data over an analog communication link. An FSK modulator comprises a digitally controlled sine-wave generator whose frequency shifts between two predetermined frequencies in response to the two logic levels of the digital data. The circuit in Figure 1 generates a sine wave by continuously sampling a single sine cycle. The output of IC 2A is proportional to the currents through R1, R2, and R3. These resistors connect together at one end to the inverting input of IC 2A, which is biased at VCC/2. Design by Israel Schleicher, Prescott Valley AZ
Simple Circuit Miniature FM Transmitter - I found this FM transmitter circuit on the internet, it works very well and it is very simple to build, even for amateurs. I managed to squeeze all the parts on small 1.5 x 2 cm PCB. When using small wire antenna and 3V power the range is 50m. The coil has 10 turns on a 3 mm diameter and is wound with 0.3 mm copper wire. The microphone is an electret type. Transmitting frequency is changed by stretching or compressing the coil. Furthermore, we can change the frequency by changing C2 capacitor (10pF capacitor with a frequency of about 88MHz, with 8.2pF 95Mhz and 6.8pF 104Mhz). Further tuning to the correct frequency is done through the coil. Transmitter can be powered by 3V button battery. __
Simple Circuit MP3 FM Transmitter - A simple MP3 FM transmitter circuit shown here can be built easily in few minutes if all parts are available to you. All the components used in this transmitter circuit are general purpose and low cost. The circuit will work as a best FM transmitter for simply broadcasting your music around your house and yard, and can be used to broadcast the output of any equipment like mp3 player, ipod, satellite, etc. __
Simple Circuit RF Power Meter - 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 sensitivety of 20k ohms/4 Watts which is adequate for low power transmitters. __
Simple FM Transmitter - There is no thrill like the thrill you get from operating equipment you have built yourself. If you have never built a project from a magazine before, let this be your first--you'll see how much satisfaction and fun you can have! __ Designed by Tony van Roon VA3AVR
Simplest FM Transmitter - 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. __
Single Chip FM Transmitter - Simple to build once chip FM Transmitter that requires only 3 - 5V to operate. This 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 barbecue. __
Single Transistor Receiver and
Transmitter Design -
Regen Receiver for the 30m Band. This receiver is surprisingly
sensitive. It's performance is far better than I had expected.
When I connected the receiver to the antenna the first time, I
hardly believed what I heared! With just one transistor this
little thing was able to hear everything - loud and clear . .
. Rolf Heine, DL6ZB
Single Transistor VCO FM Transmitter - This simple transmitter allows you to broadcast on FM radio band 87.5 - 108 MHz. It consists of a simple oscillator with silicon planar RF PNP transistor. Directly to the oscillator an antenna is connected. Due to the large amplitude of RF voltage is sufficient antenna length of about 5-10 cm. I used insulated 7cm long copper wire 1mm diameter. I eliminated the tuning capacitor, which is usual for most bugs and miniature transmitters, because this greatly complicates the tuning. From my own experience I know that if you get closer to such capacitor, the operating frequency is changed. That's why I chose to use the voltage tuning using the Voltage Controlled Oscillator (VCO). Instead of tuning capacitor the varicap (capacitance diode) is used, which changes its capacity by changing the reverse DC voltage. We can tune the operating frequency by changing the DC voltage using the trimmer P1. Varicap also provides frequency modulation. __
Small FM transmitter SMD - This SMD FM transmitter has an operating frequency of about 80 to 115MHz. Under reasonable circumstances you will be able to receive its signal at a distance of about 200 meters. Although it is low-power, it might be illegal in your part of the planet. __ Designed by Oscar den Uijl
Soft-limiter forms basis of Simple Circuit AM Modulator - 09/03/07 EDN-Design Ideas - Inserting diodes biased by reference voltages in the feedback loop of an op amp yields a soft limiter that you can use as the basis of an AM modulator - Circuit Design by Herminio Martínez, Encarna García, and Juan Gámiz, Technical University of Catalonia, Barcelona, Spain
Solar Powered FM Bug - 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 circuit will transmit. The 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, I added a regulated solar power supply and an RF amp that extends the range and improves frequency stability __ Designed by G. Forrest Cook
Spy FM Transmitter Bug - 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. __
Stereo FM Transmitter - This is a small stereo FM transmitter. Output can be tuned from 88 to 108Mhz and the transmitter can be battery powered or be used with presented low voltage power supply. This circuit is based on the Rhom BA1404 datasheet. The maximum voltage should not exceed 3V. The IC can be driven from a 7805 Regulator with a couple of 1N4001 diodes to reduce the supply voltage to about 2.8 Volts. RF output power is typically 500mW but range depends upon antenna coupling and efficiency, environment and size of antenna. A small telescopic whip has an expected range of at leaset 100 metres or more. __
Stereo FM Transmitter with BA1404 - 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 __
Subcarrier Adapter - Listen to those hidden FM transmissions. __ Designed by Tony van Roon VA3AVR
Super Simple Circuit FM Transmitter - FM transmitters can be complicated to build, but not this one. It’s about the easiest you can possibly make. And though the science of radio is well understood, there’s a magical, emotional quality about it that we don’t often stop to appreciate. You will not forget the first time you pick up a transmission broadcast from a device you soldered together, yourself, from a few bits of copper, carbon, plastic, and wire. __
Super Simple Circuit iPod FM Transmitter - FM transmitters can be complicated to build, but not this one — this iPod FM transmitter about the easiest you can possibly make. And though the science of radio is well understood, there’s a magical, emotional quality about it that we don’t often stop to appreciate. You will not forget the first time you pick up a transmission broadcast from a device you soldered together, yourself, from a few bits of copper, carbon, plastic, and wire. __
Superregen Receiver for FM broadcast or Aircraft band AM reception - This is the receiver I was bragging about on the Radio index page -- the receiver that is so sensitive it can hear the local oscillator inside a small transistor radio 30 - 50 feet away. Build one of these little gems and you will be able to hear aircraft pilots many miles away with nothing more than a 24" whip antenna. __ Designed by Rick Andersen
Synchronous Modulator - File contains two versions. This unique circuit uses a very small amount of battery current and has excellent carrier suppression. Its only shortcoming is that you must limit the input signal to 0.7 Vp-p in order to prevent distortion. To use higher input __ Designed by Andrew R. Morris
Synchronous Oscillator Converts Audio, Video to FM - 07/22/99 EDN-Design Ideas - The synchronous oscillator (SO) and the coherent phase-locked synchronous oscillator (CPSO) are universal multifunctional networks that track, synchronize, and amplify as much as 80 dB; improve SNR by as much as 70 dB; and modulate AM, FM, and FSK signals - Circuit Design by Vasil Uzunoglu, Synchtrack, Gaithersburg, MD
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