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Some Simple FM Transmitters

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#4
would it reaaly work if i connect it

will this circuit design work if i go by your diagram?(the 2nd one)
 
Thread starter #5
it should work as long as you follow the schematic closely and dont use a breadboard or stripboard

use a pcb as the metal tracks breadboard and stripboard tend to act like many little capacitors, causing the radio to not work properly

i hope that answers your question...
 
#6
Isnt the last circuit an AM receiver? I found it from CXI (Circuit exchange Intertnational) schematics.

I recommend the 2nd circuit as an FM transmitter since it worked for me.
 
#8
how do I calculate the bandwidth each transmitter delivers?
 

Nigel Goodwin

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#9
mstechca said:
how do I calculate the bandwidth each transmitter delivers?
I don't think you do, although suprisingly effective these types of transmitters are horribly crude - the more audio you put into them the higher the deviation of the output. It's not even a 'proper' FM modulation, I suspect you probably get as much AM as FM from them?.

But any FM transmitters bandwidth is dependent on the amount of modulation applied - that's why broadcasters have serious limiters on their inputs!.
 
#10
ok :eek:

how do I calculate the modulation level, and what are the units for the modulation level?
 

Nigel Goodwin

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Most Helpful Member
#11
mstechca said:
ok :eek:

how do I calculate the modulation level, and what are the units for the modulation level?
Again, I don't see how you can, the modulation action in these crude transmitters is obscure in how it works, I see no way to calculate it.

For an FM transmitter I imagine it would be measured in 'KHz per volt', or something similar?. For an AM transmitter it's in percent.

Why do you want to calculate/measure this anyway?.
 
#12
I want to be able to make my own wireless network between two computers, and further learn radio electronics.
 

Nigel Goodwin

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Most Helpful Member
#13
mstechca said:
I want to be able to make my own wireless network between two computers, and further learn radio electronics.
This isn't the way to do it!.

It's far too low a frequency, and far too low a potential data rate for networking.

Wireless network components cost very little these days and give excellent speed and performance - you would probably spend more building crude radio systems for a system more than a thousand times slower!.
 
Thread starter #14
I want to be able to make my own wireless network between two computers, and further learn radio electronics.
these are not for those kind of uses.
these are simply the basic design for audio transmitters, not data transmitters.

like nigel said, they are too low of a frequency and would get far too much interference and data loss. if you are really interested in learning about radios, the best way would probably be to buy a good-quality diy kit

i hope that helps...
 

audioguru

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Most Helpful Member
#17
Enter in a search on Google: Stereo Micromitter and the 1st link will be to Silicon Chip magazine's stereo FM transmitter project.
I've seen finished ones in stores. For only $25.00CAN on sale. They have an RF attenuator on the output which can easily be bypassed for greater range. :lol:
 
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