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Hi everyone, this is my first post in this forum. I've bought one fm transmitter hobby project kit. The circuit diagram is shown below. I did some calculations of voltage shown in second image. However I'm not certain about some calculation cos when I bring the oscillosope probe near the transistor c there's lot of noise. Is this correct? This voltage was 1. Can any body tell me how this oscillation is produced? Can i calculate the inductance in any way? Which was roughly 9nH. Any suggestions?
I don't know how that works. Can anyone plz tell me how this transistor operates and produce oscillations in this circuit?
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State Verified Answer Replies 6 replies Answers 1 answer Subscribers 73 subscribers Views views Users 0 members are here help transmitter fm circuit understand. Share More Cancel. So here are my questions - why they put a voltage divider which is connected to ground , which comprise of k and 4k7 x2 resistors at the base of 1st transistor c - I think the first transistor c amplifies the voltage and current and inverts it. Is this a Dipole Antenna?
If anyone needs any requirements to answer these questions, plz let me know. Reply Cancel Cancel. Top Replies. Anyway, just my few cents : The two first transistors are a pre-amplifier for the microphone signal. The modulation Thanks Marc and Robert. FM is a part of analog modulation so I thought I must add this question in this forum. If by any means I've broken the rules, plz let me know.
Thanks for ur replies Plz Most of the questions on this forum pertain to Analog Devices components and are generally answered by product experts from Analog Devices. So we are not really in a postion to answer a more general non The modulation signal is outputted through the 2. Then, the modulation is applied to a diode written "". I suppose this is a Varicap diode, whose capacitance changes with applied polarization voltage.
However, I cannot understand how this diode is biased and it has to be, for good modulation linearity. There shall be a magnetic coupling between the three PCB coils, so they act more like a transformer. Finding the self-inductance of one isolated coil is not that interesting. Explaning how the oscillator oscillates is rather tricky, or I am not good at it The oscillator beeing also the power output stage, chances are that the load antenna impedance will impact the oscillation frequency I would not consider this schematics a masterpiece of analog design.
2SC1959 Bipolar Transistor
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2SC1959 Toshiba Transistor C1959
Free shipping. Be the first to write a review. NPN Epitaxial Transistor. Complementary to 2SATM. Good for audio driver stage or switch application.
C1959 Datasheet PDF