سلام خدمت دوستان عزیزاقا یه مدار خیلی شاده فرستنده اف ام هستش که تقریبا تونستم وظیفه تک تک قطعاتشو بدونم البته به کمک یه سایت ولی در مورد یه خازن موندم اون سایته کامل توضیح داده ها معنی هم میکنم ولی مفهومو منظورشو متوجه نمیشملینک سایت رو مکیذارم اگه لطف کنین معنی کنیدو طوری بکنیدش که من بتونم بفهمم یا خودتون بتونید خیلی ساده توضیح بدین ممنون میشم
لینک صفخه:https://diyhacking.com/diy-fm-transmitter/
اینم عکس
اینم از متن
How Does it Work?
The circuit has three main stages, the input stage, the modulation stage, and the output. The input stage consists of capacitors C3 and C1, and resistor R1. Input signals into the FM transmitter must not contain a DC component as it would adversely affect the modulation/oscillation stage (by saturating the transistor) and therefore no FM signal would be generated. C3 is used to couple the input signal so that no DC component is fed into the transmitter. R1 provides biasing for the transistor by feeding a small amount of current into the base (which prevents the transistor from turning off).
The next stage is the modulation/oscillation stage which provides a carrier signal which is then modulated by the input signal. The oscillator consists of C2, L1, C4 and R2 with the frequency of oscillation being determined by C2 and L1 only. When power is applied to the circuit, a rush of current flows through the inductor. This rush of current will also pass through C4 via capacitive coupling which will result in current flowing through R2. Current flowing through R2 will result in a voltage drop across R2 and since R2 is connected to the emitter of Q1, the same voltage will be present on the emitter of Q1. This increase in voltage on the emitter therefore results in a smaller value of Vbe and this reduction in Vbe reduces the conduction of Q1. As C4 begins to charge the amount of current flowing through C4 reduces which results in less current flowing through R2. When this happens the voltage across R2 reduces which increases the size of Vbe and therefore increases the conduction of Q1. This increase in conduction results in C4 discharging and the whole cycle starting all over again.
Modulation is achieved thanks to parasitic capacitances inherent in BJT transistors. Between the base – emitter, base – collector, and collector – base, are parasitic capacitances whose capacitance value depends on the base current. By altering the base current these values change as well and since the oscillation in the circuit is dependent on all capacitors and inductors in the LC tank, the parasitic capacitances also affect the frequency of oscillation. Therefore, by changing the base current you change the frequency of the oscillation which is how the FM (frequency modulation) signal is produced.
قربون دستتون
جاس مهمش اونجاییه که در مورد خارن4 که با ترانزیستور سری شده هستشه
بقیشو فهمیدم
لینک صفخه:https://diyhacking.com/diy-fm-transmitter/
اینم عکس
اینم از متن
How Does it Work?
The circuit has three main stages, the input stage, the modulation stage, and the output. The input stage consists of capacitors C3 and C1, and resistor R1. Input signals into the FM transmitter must not contain a DC component as it would adversely affect the modulation/oscillation stage (by saturating the transistor) and therefore no FM signal would be generated. C3 is used to couple the input signal so that no DC component is fed into the transmitter. R1 provides biasing for the transistor by feeding a small amount of current into the base (which prevents the transistor from turning off).
The next stage is the modulation/oscillation stage which provides a carrier signal which is then modulated by the input signal. The oscillator consists of C2, L1, C4 and R2 with the frequency of oscillation being determined by C2 and L1 only. When power is applied to the circuit, a rush of current flows through the inductor. This rush of current will also pass through C4 via capacitive coupling which will result in current flowing through R2. Current flowing through R2 will result in a voltage drop across R2 and since R2 is connected to the emitter of Q1, the same voltage will be present on the emitter of Q1. This increase in voltage on the emitter therefore results in a smaller value of Vbe and this reduction in Vbe reduces the conduction of Q1. As C4 begins to charge the amount of current flowing through C4 reduces which results in less current flowing through R2. When this happens the voltage across R2 reduces which increases the size of Vbe and therefore increases the conduction of Q1. This increase in conduction results in C4 discharging and the whole cycle starting all over again.
Modulation is achieved thanks to parasitic capacitances inherent in BJT transistors. Between the base – emitter, base – collector, and collector – base, are parasitic capacitances whose capacitance value depends on the base current. By altering the base current these values change as well and since the oscillation in the circuit is dependent on all capacitors and inductors in the LC tank, the parasitic capacitances also affect the frequency of oscillation. Therefore, by changing the base current you change the frequency of the oscillation which is how the FM (frequency modulation) signal is produced.
قربون دستتون
جاس مهمش اونجاییه که در مورد خارن4 که با ترانزیستور سری شده هستشه
بقیشو فهمیدم
