Fm Transmitter for car

  Beeper Transmitter The Beep Transmitter emits a series of intermittent beeping frequency that may be easily received and picked up by any FM radio within its range.  

  Music Player Transmitter The next CD player, USB device, and mobile phone The Multimedia Transmitter sends audio signals from your PC, CD player, or smartphone to your FM audio system for playback through the system's loudspeakers without using connecting wires.

  100 meter Range Transmitter The next Two-Transistor FM Transmitter is essentially similar to the preceding design, with the exception of an additional transistor and a pair of resistor/capacitor values that have been changed to match the new circuit layout. The range of this transmitter is around 100 meters.

  150 Feet Range Transmitter The below shown One-Transistor FM Transmitter circuit's output, which can be received by any FM receiver within approximately 150 feet or less of the transmitter, provides great functionality and is suitable for wireless mic usage.

  More Transmitter Circuits The transmitter coil L1 for all the following circuits are created by hand winding 4 turns of 18 to 22 SWG super enameled copper wire over a 1 cm air cored former, using card board or plastic for the former material. The number of turns of L1 can be manually adjusted so that FM transmitter circuits are able to transmit signals within the high VHF range using 2 or 3 turns for L1, or across the lower VHF range of 50 to 80 MHz using 5 to 7 turns for L1. The variable capacitor connected parallel to the coil L1 in the all the following circuits can be a 33 pF trimmer or any FM gang capacitor.

  Circuit Description The circuit diagram for the CMOS Transmitter can be seen in the following figure. Power to the circuit is derived via B1, which is a 9 volt battery. A pair of 4011 NAND gate stages, U1c and U1d, are configured like a radio-frequency (RF) oscillator (carrier). The remaining a couple of CMOS gates, U1a and U1b, are utilized to build an audio frequency (AF) oscillator (modulator). Switch S1 helps activating an deactivating the modulation process to enable the exchange of an complex information with the Transmitter. Once the switch S1 is pressed, the AF oscillator using U1a, U1b, R4, and C1, begins producing an acoustic signal. This signal switches ON and OFF the CMOS gates U1c, U1d, R2, R3, and C2. included in the the RF oscillator stages. During the ON periods, the RF oscillator operates at 1 MHz frequency. This frequency output is delivered out to the ANT1 as an AM signal. In the switched ON position, the RF oscillator operates at 1 MHz. The fre...

  CMOS IC Transmitter Circuit The project is a straightforward AM/FM transmitter using a single CMOS IC 4011, which could be used to broadcast audio into your AM or FM Radio, TV set, CB radio, police scanner, ham radio, or whatever nearby gadget that is able to catch and reproduce radio waves. The unit will not cause disturbance on your neighbor receiving units, since the Transmitter range is just enough to be restricted to an average-size room, but as long as nobody is standing between the transmitter and the receiver.

  Morse Code Transmitter This morse transmitter circuit can be used for transmitting morse codes by tapping the switch associated with R3. The transmitter will be able to send the signal thousands of miles away which could be received by all VHF, UHF band receivers over a suitable station.

  IC 741 Transmitter Using Wire Connection In the above section we earned about wireless FM transmitter, if you are also interested to know how to make wired transmitter, in which voice could be transmitted through wires into a loudspeaker, then the following design may help The   IC 741 if configured as a non inverting amplifier   which performs the function of a pre-amplifier stage. The gain of this IC 741 preamplifier stage may be varied as desired, using the pot across its input and output pin outs. The gain setting is used to set the sensitivity of the amplifier and is set to maximum so that even low volume speech conversation may be picked through it. The mic at the input transforms sound vibrations into minute electrical pulses, which is further amplified by the IC 741 to suitable levels before applying it to the output amplifier stage consisting of a standard push-pull stage. This push pull stage is made using a couple of high gain transistors 187/ 188...

  Analyzing a Two Transistor Spy Circuit Adding a transistor stage to the above discussed single transistor FM transmitters could enable the designs with extreme sensitivity. An   electret MIC   itself has a built in   FET   which makes it very efficient and makes it a stand alone vibration amplifier device. Adding another transistor stage with it enhances the sensitivity of the device to overwhelming limits. As may be witnessed in the following diagram, the involvement of an extra transistor stage adds up to the gain of the MIC making the entire unit highly sensitive such that it now picks even the sound as low as a pin dropping on the floor . The extra transistor prevents excessive loading of the MIC thereby ensuring better efficiency to the sensitivity. Five things that that make the circuit extremely good with it reception are: The use of a fix capacitor in the tank circuit along with a adjustable trimmer. A low value coupling capacitor with the MI...

  Transmitting Music If you want your tiny FM transmitter circuit to transmit music instead of spying or eavesdropping, you would probably find the following design interesting. The proposed FM transmitter will allow combining a stereo input simultaneously from the source so that the info contained inside both the channels get into the air for an optimal reception. The design configuration is quite identical to the one that’s discussed above so does not need much of an explanation.

  Improved Stability The stability of the above circuit could be improved by tapping the antenna from one top turn of the coil as shown in the following figure. This actually enhances the response of the circuits due to a couple of reasons. The antenna gets aloof from the collector of the transistor allowing it to function freely without unnecessary loading, and the slipping of the antenna to the top further allows the relevant side of the coil to get a higher stepped up voltage induced across itself and also the coil generating a higher concentration of transmission power on the antenna. Although this enhancement may not actual increase the range of the device, it makes sure that the circuit does not get rattled when hand held, or when the grip is encircled close over the circuit inside its enclosure.

  Adjustable Coil Slug The next design in the list is much superior to its previous counterparts since it uses a slug based variable inductor. This enables the transmitter to be   tuned by adjusting the slug core   using a screwdriver. In this configuration we can see the coil being attached to the collector of the transistor which allows a massive   200 meters range   to the design, with a current that may be not more than 5mA. The MIC stage is isolated from the base with the help of a 1u capacitor and the gain of the mic could be well tweaked by adjusting the series 22k resistor. This circuit could be rated as the best as far range is concerned however it may lack stability which could be improved, we’ll learn how in the following explanation.

  Better Saturation Capability The next   FM transmitter design   is a bit different than the above types. Fundamentally the design could be classified as a common emitter type, unlike the others which are rather common base types with their design. The circuit employs an inductor at its base which adds a better saturation capability to the device which in turn allows the transistor to respond in a much healthier way.

  Incorporating Q Factor Below's another circuit you would like to know about. The circuit basically makes use of the “Q factor” of the tank network achieved from the coil and the capacitor for generating a relatively high voltage. This stepped up potential attributes the circuit with a rather   longer range of transmission . For an improved performance make sure the coil and the capacitor are positioned as close as possible. Insert the coil leads as deep down the PCB as possible in order to make it tightly hugging the PCB. C2 value could be tweaked for achieving even better response from the circuit. Preferably a 10pF could be tried. The coil is made of 5 turns of 1mm thick super enamelled copper wire, with 7mm diameter.

  Using Tuned Circuit The second example below shows another single transistor FM spy circuit that incorporates a tuned circuit or a frequency determining stage in it. In the original prototype the coil was created by etching a spiral track layout on the PCB itself, however for optimal gain and performance such etched antenna coil must be avoided and the traditional wire wound type of coil must be employed.

  One Transistor Design You might have already come across a host of these extremely basic one transistor FM transmitter circuits, however these may incorporate certain drawbacks as mentioned below: No substantial transmitting range. No enhanced sensitivity range Use 1.5V for operating which render limited capabilities. Among the first in the line, which is probably the simplest is shown in the following circuit diagram. Surprisingly it does not employ a MIC, rather the antenna coil itself performs a dual function of detecting sound vibrations and also transmitting it into the atmosphere. The design is void of a frequency determining stage and thus does not come under tuned transmitter circuits (we’ll discuss about these later on in the article). Circuit Operation The following single transistor FM spy circuit may be understood as follows: When switched ON, the capacitor 22n inhibits the transistor from switching until it gets charged. A soon as this happens the transist...

An FM transmitter can be a great, low-cost way to breathe new life into a flagging car audio system because they're easy to use. Instead of upgrading the head unit or installing expensive equipment such as an FM modulator, an FM transmitter opens up a new world of listening options for a relatively low cost and almost no effort. The problem is that FM transmitters aren't foolproof, and they don't always work right. If you're trying to use an FM transmitter in your car, and you hear static or interference from radio stations, these five tips can improve your listening experience. Why Choose an FM Transmitter? When MP3 players were first introduced, they represented a change in how people listened to music in their cars. If you invested in an MP3 player, even with the storage limitations of the day, you could bring hundreds or thousands of songs along with you without fumbling with dozens of cassettes or CDs. With the adoption of smartphones acro...

    10 Simple FM Transmitter Circuits Explained An FM transmitter circuit is a high frequency wireless device which is able to transmit voice signals into atmosphere so that it can be received by a corresponding FM receiver circuit for reproducing the voice signals in a loudspeaker. Here we’ll discuss how to build small FM transmitter circuits using 10 different methods, one that consists of wire link from the transmitter to the receiver, and the other which is completely wireless and can be used to eavesdrop a particular conversation over a range of about 30 meters, over an ordinary FM radio. . The above extraordinary capabilities have forced the legal authorities to enforce stringent laws against the use of these transmitters without permission, so before you make and use one of these make sure you have all the legal formalities completed. Wireless Design: I will begin with a transmitter which I have actually built numerous number of times and tested it thoroughly. Subsequen...