Mutchus

This FM transmitter circuit can be used as a wireless microphone,  can be received by an ordinary 88- to 108-MHz FM broadcast receiver. For the power supply, this transmitter circuit is powered by a 9 V battery. To comply with the radiation limit of FCC rules, keep the antenna length under 12 inches. L1 is 6 turns of #24 wire wound around a pencil or a 1/4″ form, with turns spacing of 1 wire diameter. C6 is a gimmick capacitor which has value about 1 pF..  9V Wireless Microphone FM Transmitter Circuit Diagram

Build a Simple Solar Powered Long Range FM Transmitter Circuit Diagram . This is very stable, harmonic free, long range fm transmitter circuit which can be used for fm frequencies 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.    Simple Solar Powered Long Range FM Transmitter Circuit Diagram Theory The solar power supply consists of a small 18V PV panel which charges a 1000uF electrolytic capacitor. The capacitor keeps the circuit running during brief interruptions of light, such as a bird flying over the PV panel. T...

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. This fm transmitter antenna is connected to the mid point of the antenna length L1 and preferably between 8-12 inches. FM Transmitter is only used for experiment and learning materials are not to be used for day-to-day, because the use of FM transmitter frequency regulated and protected by law may be understandable.

This circuit is a simple two transistor (2N2222) FM transmitter. No license is required for this transmitter according to FCC regulations regarding wireless microphones. If powered by a 9 volt battery and used with an antenna no longer than 12 inches, the transmitter will be within the FCC limits. The microphone is amplified by Q1. Q2, C5, and L1 form an oscillator that operates in the 80 to 130 MHz range. The oscillator is voltage controlled, so it is modulated by the audio signal that is applied to the base of Q2. R6 limits the input to the RF section, and it's value can be adjusted as necessary to limit the volume of the input. L1 and C6 can be made with wire and a pencil. The inductor (L1) is made by winding two pieces of 24 gauge insulated wire, laid side by side, around a pencil six times. Remove the coil you have formed and unscrew the two coils apart from each other. One of these coils (the better looking of the two) will be used in the tank circuit, and the other can be us...

Circuit diagram: Description 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 (eg, Jaycar Cat LF-1536). 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. author : Peter Goodwin Source http://www.extremecircuits.net/2010/05/simple-am-transmitter.html

This circuit is a simple two transistor (2N2222) FM transmitter. No license is required for this transmitter according to FCC regulations regarding wireless microphones. If powered by a 9 volt battery and used with an antenna no longer than 12 inches, the transmitter will be within the FCC limits. The microphone is amplified by Q1. Q2, C5, and L1 form an oscillator that operates in the 80 to 130 MHz range. The oscillator is voltage controlled, so it is modulated by the audio signal that is applied to the base of Q2. R6 limits the input to the RF section, and it's value can be adjusted as necessary to limit the volume of the input. L1 and C6 can be made with wire and a pencil. The inductor (L1) is made by winding two pieces of 24 gauge insulated wire, laid side by side, around a pencil six times. Remove the coil you have formed and unscrew the two coils apart from each other.    FM Transmitter Circuit Diagram One of these coils (the better looking of the two) will be used in th...

Many beginners give up playing with RF due to the difficulty of building coils and problems with self oscillations that are common in many electronic circuits of RF. I always point out to beginning the construction of a small FM transmitter, myself have made available a simple circuit and an explanatory tutorial in Article Micro FM Transmitter and Micro Spy FM Transmitter Spy Bug in SMD. The RF is really a very critical area, but on the other hand, it is the most rewarding, especially when we see one of our creations give the air of grace and drop its waves through the air. I always say that we learn more from mistakes and making mistakes is part of the electronics, I even today burst capacitors and transistors see loose tufts of smoke, the difference is that today I have fun with these errors. Here I will publish a simple electronic circuit RF, so simple that does not use a single coil. This is a small tone transmitter modulated (AM) for the band of medium waves (AM) using an integrat...

Build a FM Stereo Transmitter  Circuit Diagram . You'll find that this is a very easy project to build. It will transmit good quality sound in the FM band ( 88 - 108 mhz ). One inportant item is that the IC chip operates on 3 volts DC. The chip will get destroyed if it is operated on any voltage higher than 3.5 volts. The antenna can be a standard telescopic antenna or a 2 foot length of wire. The input is in the millivolt range and you may need to add additional pots for the inputs. I was able to use this circuit for a walkman and a portable CD player in my car. I used the headphone jack on both and varied the signal with the volume control. FM Stereo Transmitter  Circuit Diagram To adjust the circuit tune your FM radio to a quite spot then adjust the trimmer capacitor C8 until you hear the signal that you are transmiting. When you have a strong signal adjust the resistor R4 until the stereo signal indicator lights. If the input is to high of a signal you may over drive the I...

A very simple and useful circuit that require few external components and operates in FM band ( above 100 MHz ). This circuit diagram transmitter needs to be powered from a 9 volts battery or from another 9 volts regulated power supply . The tuned coil L1, has two output tappings for the antenna connection, marked "A" and "B". These are both low-level outputs and you choose which tapping you want to use ( stable low range, or more unstable but higher range). Tap B (2.5%) takes just a very small portion of signal from the oscillator circuit and therefore gives a very frequency stable transmitter. The output level (around 2.5mW) and range are therefore somewhat reduced.  Tap A (10%) delivers very much more power (around 10mW) to the antenna load. This gives you a greater range, but at the expense of frequency stability. All component leads should be kept as short as possible. The LINK wire on the PCB should lay flat on the PCB. Use the cutoff from a resistor leg. Ante...

AM Transmitter circuit analysis Parts of the transmitter AM: 1. The input signal The input signal in the form of electrical signals generated by mechanical equipment modifier into electrical vibrations. Tools that generate these signals include a microphone, LPs, and others. Power signals issued by these tools, the amplitude is still too small, so it requires strengthening again.   2. Audio amplifier Audio signal that is still small signal voltage amplitude will be strengthened, so that the resulting stress intensity audio signal is strong. Amplifier section can be either audio amplifier or preamp only with the amplifier end. 3. Oscillator circuit Oscillator circuit is an electronic circuit that functions to produce high vibration. The frequency of the resulting circuit is high because if low, this electrical vibration will not radiate much. Oscillator which is used in the transmitter is the oscillator RF. RF oscillator is a high frequency generator that serves as a signal carrier....

Let’s construct a low-power FM transmitter 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 contrastm the transmitter schematic we present here eliminates some of those problems, using varactor diode for tuning and modulation, givind great sensitivity without an audio amplifier.  FM Transmitter – How it works The figure below shows the schematic of the transmitter which consists of two stages: an oscillator and an output amplifier. Modulation is from an electret microphone but you can use a low power audio source.  Oscillator stage Transistor...

This circuit provides an FM modulated signal with an output power of around 500mW. The input Mic preamp is built around a couple of 2N3904 transistors, audio gain limited by the 5k preset. The oscillator is a colpitts stage, frequency of oscillation governed by the tank circuit made from two 5pF capacitors and the inductor. ( Click here for Colpitt Oscillator Resonant Frequency Equation.) Frequency is around 100Mhz with values shown. 4 Transistor Transmitter Circuit Diagram Audio modulation is fed into the tank circuit via the 5p capacitor, the 10k resistor and 1N4002 controlling the amount of modulation. The oscillator output is fed into the 3.9uH inductor which will have a high impedance at RF frequencies. The output stage operates as a class D amplifier, no direct bias is applied but the RF signal developed across the 3.9uH inductor is sufficient to drive this stage. The emitter resistor and 1k base resistor prevent instability and thermal runaway in this stage.