Simple 555 Timer AM Transmitter Schematic for Science Fair Project

We have published so many FM transmitter circuits at CircuitsGallery, so this time I am going to introduce a simple AM transmitter circuit based on 555 timer. Firstly let us have a look at what is Amplitude Modulation. AM is a modulation technique where the amplitude of carrier varies according to the input message signal. AM has been a widely used modulation technique due to its longer range but has the disadvantage of lesser noise immunity. It is commonly used in walkie talkie applications.

Here 555 multivibrator generates a frequency of AM range so you can receive the transmitted audio signal in the AM radio receiver. This simple AM transmitter is suitable for school projects.

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Multi Channel Remote Control System

Here is a hobby circuit of a multi channel remote control system, by which you can control 8 different appliances. The main sections of this multi channel remote control circuit are the RF receiver and transmitter. By using this circuit we can control 8 devices, each of them independently by pressing the push buttons. When the button is pushed, corresponding relay is turned ON and is turned OFF on the next push. Here the relay load current is dependent on the relay used. A serial encoder IC HT12E and a serial decoder IC HT12D are used, where the encoder IC encodes the parallel data to serial and decoder IC decodes the serial data to parallel during the wireless transmission. You must need a regulated power supply of 5 volt for this circuit because ICs 7476 and 74138 requires 5v for its operation. The main advantage of this system is that it does not require a ‘line of sight’ as compared to IR remote control systems; also it gives longer distance control.

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Most simple FM transmitter circuit diagram

This is the most simplest and single transistor FM wireless transmitter circuit that ever posted in CircuitsGallery. In telecommunication field, frequency modulation (FM) transmits information by changing the frequency of a carrier wave according to message signal. FM uses VHF radio frequencies usually 87.5 – 108.0 MHz to transmit and receive the FM signals.

Here I will give you the explanations about FM transmitter, how to make a FM transmitter and how a simple FM transmitter is designed and assembled etc. The performance and working of a wireless audio transmitter circuit mainly depends on inductor coil specification and the value of variable capacitor. Even a slight change of inductance or capacitor can shift the harmonic frequency from the VHF (88-108 MHz) band.  This article will enable you to answer “how to build an FM radio transmitter?”. Also you will get the confidence to build your own FM transmitter.

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Simple short range portable FM transmitter circuit diagram

This is a simple 2N2222 transistor based radio FM transmitter circuit within the FCC (Federal Communications Commission) limit, that is no license is necessary for using this stable FM transmitter circuit. What is an FM transmitter? FM stands for Frequency Modulation and FM transmitter is a radio frequency (RF) transmitter which uses frequency modulation of audio signals. Frequency modulation means that the frequency of a carrier signal is changed according to the input audio signal.

The portable FM transmitter is able to transmit sound or music to any standard radio FM receiver. The range of this transmitter is near to 120 meters. Audio signal is applied via a condenser micro phone, which is a capacitive sound sensor. Simplicity and portability makes this transmitter circuit superior to other FM transmitters. The transmission frequency of this FM transmitter can be adjusted using the variable capacitor C7. The main applications of this circuit includes FM transmitter for car, walky talky, wireless audio transmitter etc.

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Simple FM Transmitter circuit schematic Long range, short range using VMR6512 Hi-Fi Audio FM transmitter module

This article gives the FM transmitter circuit schematics with necessary explanation. The main component used here is the VMR6512 IC which is a highly integrated FM audio signal (Hi-Fi Audio FM) transmitter chip. You can use this as FM radio transmitter for different applications such as FM transmitter for car, digital FM transmitter, Hi-Fi wireless headphone, Conference Broadcasting System, accessories of audio-visual entertainment equipment and radio station in campus. This wireless audio transmitter chip integrates superior digital signal processor (DSP), matching network, frequency synthesizer and RF power amplifier. So it can grasp FM audio modulation without any external components. You need a pre amplifier section in order to transmit our voice directly as FM. Refer my condenser mic pre amplifier circuit.

Related article: Most simple FM transmitter circuit diagram

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