FM 9V transmitter circuit with expllanation

This circuit diagram transmitter is 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. Antenna length for circuit diagram transmitter varies with frequency for optimum distance: 90MHz 80 cm, 95MHz 75cm, 100MHz 70 cm, 105 MHz 68 cm. The frequency determining elements (L1, C5 and C6) form a simple LC tuned oscillator. The inherent problem with this type of circuit diagram transmitter is that any external load (antenna) will change the operating frequency.

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Atv Jr Transmitter 440Mhz Circuit Diagram

This low-power video transmitter is useful for R/C applications, surveillance, or amateur radio applications. Seven transistors are used in a crystal oscillator-multiplier RF power amplifier chain, and a high-level video modulator. A 9- to 14-Vdc supply is required. Output is 0.4 to 1.2 W, depending on supply voltage. 

Atv Jr Transmitter 440Mhz Circuit Diagram

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Telephone transmitter

This is a simple, but very useful schema that can be used to transmit telephone conversations. When the telephone receiver is on hook the voltage across the lines will be about 48 volts. The preset R7 is so adjusted to obtain a 24.7 V across between the cathode of D2 and ground. At this voltage the Zener diode D2 will be in breakdown and the transistor T1 will conduct. This makes the transistor T2 OFF. When the receiver is off hook, the line voltage drops to about 11 volts. This makes the transistor T1 OFF and subsequently the T2 ON. The T2 in switched ON condition will provide a DC path for the transistor T3 used in the FM transmitter section.









The transistor T3 is wired as a common emitter radio frequency oscillator. In simple words the transistor T2 serves as an ON/OFF switch for this oscillator. The modulated signal will be available at the collector of transistor T3 and the signal id fed to the antenna via capacitor C5.




Notes.

* Assemble the schema on a good quality PCB.
* For L1 make 45 turns of 36 SWG enameled copper wire on the resistor R6 itself.
* The resistor R6 must be a 1M, 1 watt resistor.
* For L2 make 3 turns of 21 SWG enameled copper wire on a 12 mm plastic former.
* For antenna, use a 1 meter insulated copper wire.
* The capacitor C3 can be a 50pF trimmer.

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FM Transmitter Circuit with MAX2606

FM transmitter schema which is build using single chip of MAX2606. A very simple FM transmitter connects your home-entertainment system to a portable radio that will be carried surrounding the house and into the back yard. As an example, it is possible to play music on the CD player in your private 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 allows you to choose a channel by tuning above the FM band of 88MHz to 108MHz. Output power is about -21dBm into 50 (most nations accept emissions below 10dBm in the FM band).

The home systems left and right audio signals are summed by R3 and R4, and attenuated by the (optional) potentiometer R2. R2s wiper signal serves as a volume adjustment by modulating the RF frequency. Signals above 60mV introduce distortion, so the pot attenuates down from that level.

In the absence of a common FM radio antenna, 75cm (30 inches) of wire will suffice as a transmitting antenna. For most effective reception, it need to be mounted parallel with the receiving antenna. The IC operates on a single power supply voltage inside the range 3V to 5V, but it is best to regulate the applied voltage to reduce frequency drift and noise.

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Simple FM transmitter with 2N3904

In this section discuss about the series of mini fm transmitter, with broadcast coverage of about 300-400 meters. when using a 9 volt working voltage, the transmit power of about 300 meters and when using the working voltage 12 volts, the range of about 400-450 meters, depending on the antenna you use.

This scheme of simple fm transmitter

For L1 and L2 windings 5 times the wrap, you can use a pen to fill melilitnya so neat and after lepaslah content of these pens. C5 is used for placement of broadcasting frequencies, can be tuned between 88-108 mhz, to reach further use steering antenna or Yagi antenna.

Part List

C1 = 0.001uF

C2 = 5.6pF

C3 = 10uF
C4 = 10uF
C5 = 3 - 18pF Adjustable capacitor

R1 = 270R

R2 = 4.7K

R3 = 10K

R4 = 100K

R5 = 4.7K

R6 = 4.7K

Q1 = 2N2222A

Q2 = 2N3904

L1 = 5 turn

L2 = 5 turn

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Beacon Transmitter Wiring diagram Schematic

Simple Beacon Transmitter Circuit Diagram.This transmitter can be used for transmitter hunts, for remote key finding, or for radio telemetry in model rockets. It can be tuned to the two meter band or other VHF bands by charging Cl and Ll. 11 is four turns of #20 enameled wire air wound, 0.25 inch in diameter (use a drill bit), 0.2 inch long, center tapped. The antenna can be 18 inches of any type of wire. IC2 functions as an audio oscillator that is turned on and off by IC1 about once per second. The range of the transmitter is several hundred yards.

Simple Beacon Transmitter Circuit Diagram

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Transmitter and Receiver AM Superheterodyne

TRANSMITTER AND RECEIVER AM SUPERHETERODYNE

Distribution of information from one place to another can be done with a wide - variety of ways. As one way to distribute information in a radio communications technique, was made with modulated AM transmitter rise. The term superheterodyne stands for supersonic heterodyne, which can be interpreted as the generation of mixed frequencies above the hearing.

Transmitter

Receiver

-AM-Transmitter

AM transmitter is a transmitter that utilizes analog modulation techniques are AM (Amplitude Modulation), to transmit information signals. The source carrier is driven by a crystal oscillator at the carrier frequency or multiples below. The amount of output frequency can be adjusted by changing the value of L and C. Cultivated constant frequency emitted wave output generated for the better. This was followed by a buffer amplifier tuned. With the buffer labored to frequencies generated by the oscillator constant. Signal information entered on this circuit to be mixed with a carrier signal. At the transmitter, there are a series of modulators, which generally is a class C amplifier Class C amplifier is actually resulted in the emergence of unexpected flaw in the envelope modulation signal containing information. The output of RF amplifier is transmitted via an antenna.

Superheterodyne-AM-Receiver

AM receiver functions to receive signals modulated AM and do the demodulation of the signals. The signal was first received by the antenna, then the selection signals are separated is then amplified to a level that can separate the information signal from the signal (carrier) at the time of the AM demodulator or detector AM. Recipients an old-fashioned AM

used for receiving amplitude modulated signals typically use the principle of a tuned radio frequency or TRF. Recipients of this kind have poor selectivity adjacent signals, especially when required to tune in scope - a wide frequency range.

Therefore now superheterodyne receiver was developed to improve the selectivity of the channel adjacent fatherly (adjacent channel selectivity) of this by placing the bulk of the frequency selectivity at the level - the level of intermediate frequency (IF) after the first frequency conversion much easier fatherly get this selectivity in the IF, because stay tuned to the IF circuit and does not change even if the selected stations - different stations. Superheterodyne principle occurs when when two sinusoidal signals with different frequencies are mixed, so that they multiply or add to each other and the output signal will contain components - the component signal at a frequency which is the sum, difference and of the two original frequencies. There is also a mixture of harmonics of this signal, but if the second fundamental frequency is selected with the heart - this heart does not interfere with each other (interference).

The first level of a tuned RF functions to improve the ratio S / N. This level also provides a little perbaiakn RF selectivity and a decrease in back of the oscillator beam. Then tune the RF output is fed to the input signal from an oscillator circuit where there penyampur generation with tuning capacitance, and a third tuning capacitor (tuning capacitor) together (ganged) mechanically on a common axis and button settings. Penyampur oscillator and can be a separate circuit or it can also be combined as in the series penyampur autodyne. Next penyampur fed into two IF amplifier tuning, which remains tuned and has sufficient selectivity to reject signals from the channel boundaries. The output of the IF amplifier is inserted into the detector, where the audio signal generated back or in demodulation. The detector also provides a signal for automatic acquisition settings (Automatic Gain Control).

AGC signal applied to one or several of IF and RF amplifiers. Audio output, transmitted through a volume control to the audio amplifier, which usually consists of one low-level voltage amplifier followed by a

power amplifier and finally connected to a loudspeaker.

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