#TWO TRANSISTOR FM RECEIVER SERIES#
Boost Converter LM2587 The LM2587 series of regulators are monolithic integrated circuits specifically designed for flyback.BF199 Transistor has 50mA collector current and 25V Collector-Emitter voltage. It is suitable for use with microcontrollers.ĢN2222, 2N3904, 2N4401, BC337 (Some transistors' pin configuration is different from BC547, check the pin configuration before changing it in a circuit)īF199 is in BF Transistor Series and in TO-92 sheath. It is contained in a TO-92 case designed for medium power applications. The NPN Bipolar Transistor is designed for use in linear and switching applications. The antenna cuts the radio waves and converts them into alternating currents applied to the receiver, and the receiver outputs the desired information.īC547 is an NPN Transistor commonly used in low power amplifier circuits. What are BC547 and BF199? I will explain them to you.Ī radio receiver is an electronic device that receives radio waves and converts the information carrying them into a useful form. Increasing the supply voltage to the circuit will increase the radiating power and therefore increases the range.Here is a very simple and effective circuit using only 4 transistors.This will alter the frequency of carrier signal. The capacitance of capacitor VC1 can be changed using the trimmer.This way it transmits the audio signal and reaches any receiver that is within 30 meters. The modulated signal is then radiated to the antenna. This signal of fixed frequency will be modulated by using the incoming audio signal by the transistor. This cycle continues and a signal of fixed frequency will be generated across the tank circuit. Now there will be no charge in the Capacitor and Inductor starts discharging pushing the current to Capacitor while charging it in the opposite direction. This charges the inductor the charge is exhibited by means of magnetic field around indictor. The electric charge built up across Capacitor depletes while pushing the current through inductor. When capacitor reaches Vcc, it stops charging and forces current through the inductor. When current flows through inductor it resists the current flow whereas capacitor charges to the level of Vcc. This tank circuit basically produces a signal of fixed frequency. The important thing here is the LC tank circuit. The transistor follows the incoming audio signal. Capacitor C1 removes the DC noise from the audio signal and feed it to the base of transistor Q1.Ĭircuits Library - 220+ practical circuits When user speaks to the mic the voltage varies at the divider junction producing a audio signal. The microphone is used to receive the audio signals which is powered and biased using the resistor and internally the microphone has a capacitive plates which develop voltage across it when audio waves hit its diaphragm membrane. The circuit shows the FM Transmitter with power supply of 3.3 V.
This in turn received by FM receivers that are tuned to pick up signal of transmitted frequency and demodulated to recover the original audio signal.įM signal is obtained by varying the carrier frequency and it has two frequencies which are message signal frequency and carrier signal frequency by that way message signal is transmitted and at receiver original signal will be obtained. This modulated signal possess enough power to be radiated aka transmitted through antenna. This powerful carrier signal is then modulated or coded using the actual audio signal by a process known as modulation ( explained here ). In a FM transmitter circuit, weak audio signals(message signals) are transmitted with the help of a carrier signal which is possess high power. Related circuit: FM spy bug circuit using transistor Components Required The circuit is powered by 3.3V battery and includes a NPN transistor, a LC tank circuit and an antenna. This radio Transmitter transmits signal up to a range of 20m-30m. This article shows you a simple FM transmitter circuit diagram and explains in detail about its working and part selection method. These transmitter circuits may not provide long range like circuits that use dedicated FM chips but it will get the job done. Single transistor FM transmitter circuits are quite famous since it is easy to build and cost less.
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