FM TRANSMITTER

Thread Starter

warmachine

Joined Jul 24, 2021
15
Hello everyone,
I need to design a fm transmitter circuit for about 1 km distance . I want to know that ,how to calculate the components value , how the circuit will work , please help
Thank you
 

KeithWalker

Joined Jul 10, 2017
2,453
Hello everyone,
I need to design a fm transmitter circuit for about 1 km distance . I want to know that ,how to calculate the components value , how the circuit will work , please help
Thank you
First you need to define what frequency you will be using. Then you will need to check if it is legal to transmit at that frequency in your area. The next step is to check on the internet to find a suitable circuit or tutorial. We will try to help you if you have problems getting it working but we are not a free electronic circuit design service.
 

MrAl

Joined Jun 17, 2014
9,335
Hello everyone,
I need to design a fm transmitter circuit for about 1 km distance . I want to know that ,how to calculate the components value , how the circuit will work , please help
Thank you
Hi,

This is the homework section so you are supposed to show your best attempt first.

I would ask though, how much theory have you had on FM radio transmission. That will give you some idea how to go about doing this. Start with a block diagram of the required sections that would need to be implemented with actual electronic parts like transistors and resistors, etc. Another question is can you use IC chips also or just transistors for the main active components.
 

Thread Starter

warmachine

Joined Jul 24, 2021
15
Hi,

This is the homework section so you are supposed to show your best attempt first.

I would ask though, how much theory have you had on FM radio transmission. That will give you some idea how to go about doing this. Start with a block diagram of the required sections that would need to be implemented with actual electronic parts like transistors and resistors, etc. Another question is can you use IC ch nhiips also or just transistors for the main active components.
Hello sir,
Yes i have an idea about Fm transmitter and it's theory
For 2nd i will use transistor as i am beginner in electrons so it will help me to learn some new concepts but the main challenge is how to calculate the components value bcz on Google i didn't find any usefull articals yet soo how should i proceed ?
 

Ya’akov

Joined Jan 27, 2019
6,260
Hello sir,
Yes i have an idea about Fm transmitter and it's theory
For 2nd i will use transistor as i am beginner in electrons so it will help me to learn some new concepts but the main challenge is how to calculate the components value bcz on Google i didn't find any usefull articals yet soo how should i proceed ?
Do you have a circuit you will be calculating the values for?
 

Audioguru again

Joined Oct 21, 2019
4,921
It sounds like you are trying to learn about electronics yourself without a teacher or text books.

The FM broadcast band is around the Very high frequency of 100MHz where an inductor is a few turns of wire with no core and capacitors are almost nothing and stray wiring capacitance has a large effect.
 

Audioguru again

Joined Oct 21, 2019
4,921
The Circuitbasics FM transmitter circuit is too simple to work properly:
1) The radio frequency will change as the battery voltage runs down. Add a voltage regulator.
2) The radio frequency will change if something moves towards or away from the antenna. Add an RF amplifier transistor.
3) Capacitor C4 has a 10 thousand pF value that is way too high and reduces all high audio frequencies. In my FM transmitter I use 470pF (21 times less).
4) It is missing the pre-emphasis (high audio frequencies boost) that all FM radio stations use to match the de-emphasis that all FM radios have. Then the received sounds will be very muffled.
 
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