Simple and Mini FM Receiver

This is a very simple and mini fm radio receiver with good performances that works great even if the sensitivity is not too high. The working principle of this fm receiver may seem a little unusual. It is made of an oscillator (T2 and T3) that is synchronized with the received frequency of T1. This transistor works as a broadband preamplifier in VHF range.

Mini FM Receiver Circuit Diagram :

The oscillator is adjusted between 87 … 108 MHz with C5. Because of the synchronization, the oscillator output will have the same frequency deviation as the received signal from the fm antenna. This deviations are caused by the broadcasted audio informations. The frequency modulated signal show up on P1 + R5. Low pass filter R6/C6 extracts the audio signal and then is amplifier by T4 … T6 and transmitted at the output through C9 capacitor.

The coil details are presented in the fm receiver circuit diagram. The radio receiver is adjusted on different stations with the help of C5. P1 potentiometer is adjusted untill the best reception is obtained. If we attach an audio amplifier and a speaker then this fm receiver can be made very compact as a pocket radio.

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FM Moulator with IC 555

FM Modulator circuit is a simple FM modulation circuit using IC 555, where the resulting modulated signal has a tenuous meeting depends on the signal frequency information. 

The resulting signal can be spelled out quite nice and stable so that the result will be more perfect. No winding or inductor in series modulator, so you do not need to bother to make a winding and calculate the value of the coil that you created it. With this circuit the desired value of frequency modulation can be obtained easily by calculating the frequency of IC 555 in general, which is determined by the resistor 6.8 K and 3.3 K and 0.1 UF capacitor. To obtain the other frequencies of your stay replace one or all three components.

Actually fm modulator ic 555 circuit is very simple though, but I think it reliable enough to handle a simple application purposes that do not require a big power or a very high frequency. But if you want more power you can add the RF amplifier circuit at the output of this circuit. Thus, the results of modulated signal can be amplified with the help of a series of supporters. In accordance with my experimental series modulators can work well at frequencies below the MHz range, because it is not IC IC 555 which is devoted to support of a very high frequency. You can use oscilltor transistor circuit, XTAL or others if you need a very high frequency.

The difference circuit with IC 555 on the multivibrator circuit in general is the use of pin 5, on the FM Modulator circuit is pin 5 of IC 555 is used as input information signal, which in turn will influence the shape of the output signal (modulated). But in applying this 5 pin multivibrator functions normally associated with 0.01 UF capacitor or left alone.

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FM Receiver based on CXA1019

Its a high quality FM receiver circuit based on IC CXA1019 . CXA1019 is a monolithic silicon bipolar radio FM / AM receiver IC for Sony. Built in circuitry within the CXA1019 includes RF amplifier, mixer, oscillator, amplifier, quadrature detection circuit, tuning LED driver control electronic volume, FM detector, etc. HF section is only used in this circuit. The IC can be powered by a figure between 3 to 7 V DC and can lead to an 8 ohm speaker

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5W PLL FM Transmitter

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.

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