![]() ![]() The coil can be taken so that the high frequency signal can be reached by the receiver. When the required number of turns is reached the coil is cylindrical. The coil used in the circuit is a simple air core inductor made with 4 turns of 22 SWG copper wire with the core having a 4mm internal diameter. The value of the variable capacitor is adjusted to 20pF because variable capacitors with this value are readily available. This circuit is so designed that you can tune the radio receiver with the help of the Variable Capacitor. The message signal that is received through the circuit is extracted through the resistor R1 and then it is fed to the audio amplifier over a 220nF coupling capacitor (C1). By adjusting the variable capacitor the resonance frequency changes and we can tune the circuit anywhere between 88 and 108MHz. In this circuit, the trimmer VC sets the resonance frequency of the circuit. Capacitor VC, and along with T1 makes the construction for the Colpitts oscillator. The transistors BF495(T2) with Inductor L. This is by far one of the most complicated circuits made with very few components. Not only it receives the FM signal it also amplifies the received signal with the help of an lm386 OP-Amp IC to drive a speaker. ![]() ![]() And for our first circuit, we tried something similar. Most of the circuits we have found on the internet have one thing in common, and that is they all have a two-transistor configuration. The Two Transistor FM Radio or the Direct (TRF) FM Receiver You can check those projects out if you want to learn more about those projects or you can check the simple FM transmitter circuit built using basic electronic components like transistors, capacitors, coil etc. Now if you want to save time, you can straight away buy the RDA5807 FM receiver module and use it for your project, we have already built a Voice Controlled FM Radio using Arduino and Google Assistant and Arduino Based FM Radio using RDA5807. So in this tutorial, we did just that by building a few circuits on a piece of perf board and testing each circuit to see their working and what can be done to improve this, and in the end, we will let you know all the details. Because just like us we found a lot of people trying to get these circuits to work but fail, and a lot of discussion forums are filled with questions "Do these simple DIY FM Receiver circuits really work?" Recently we thought of building a simple FM receiver circuit, so like always we started googling for possible circuits that can be used to fulfill our requirements, and as expected we found a lot of circuits on the internet, but the question remains how good or useful will they be when we put those circuits to the test. ![]()
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