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20mhz RF circuit help me

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16mofed84

New Member
Hello
This is the first post in this forum
I want to make a Circuit to send and receive data
I want to use 2 Crystal (20mhz)
Such as those found in games (Games Car)
 

mneary

New Member
20 MHz or 20 mhz? 20 millihertz isn't a practical radio frequency. 20 MHz is already licensed in most countries.
 

16mofed84

New Member
Function is transfer the sound from place to another
Distance is 10 meters
But the important thing is to use the crystal because its very accuracy (20.000Mhz)
Thank you for mneary your reply
 

Sceadwian

Banned
There are inexpensive commercial units you can buy that will do what you want 16, why are you trying to build the circuit yourself?
 

EN0

Member
You would have to have a LONG antenna for that frequency if you want it to be very effective.

Austin
 

Sceadwian

Banned
Not necessarily EN, all those clocks you see in the US that advertise they're atomic get their signal from a 5 10 or 15mhz signals from Colorado. They don't have very large antennas.
 

16mofed84

New Member
thank you,,

I want to understand how it works
And do one
I have many equipments ,coil, transistors....
and
I want to use it
 

16mofed84

New Member
Not necessarily EN, all those clocks you see in the US that advertise they're atomic get their signal from a 5 10 or 15mhz signals from Colorado. They don't have very large antennas.

why large antenna?????
in car game (27Mhz) antenna is 20cm
the Differences is 7 Mhz!!
 
If I were you then I would try some of these circuits.

For the inductor values, if you don't get the frequency right then try this website:RADIO CALCULATIONS


For the Low power fm transmiter:

When assembling the fm transmitter circuit, make sure the rotor of C3 is connected to the +9V supply. This ensures that there will be minimal frequency disturbance when the screwdriver touches the adjustment shaft. You can use a small piece of non copper-clad circuit board to make a screwdriver – this will not alter the frequency.

Q1 is a conventional Colpitts oscillator design. The audio signal applied to the base of Q1 causes the frequency to change, as the transistor’s collector current is modulated by the audio. This provides the frequency modulation (FM) that can be received on any standard FM band receiver.

The inductors are 9.5 turns of 1mm diameter enamelled copper wire. They are close wound on a 3mm diameter former, which is removed after the coils are wound.
The output is a low power of 100 mW, but for some of you this fm rf transmitter can delivers the desired power for broadcasting on your street or with a proper antenna you can cover a small neighborhood. If you need a power wireless fm transmitter use the above menu, you can find transmitters starting with low fm power up to high power fm transmitters.

but just a heads up if they catch you using this bandwith then you are in big trouble, and FYI HAM Radio operators are crawling all over this bandwidth, I would try a much higher frequency (500 Mhz) remember that the data tranasfer rate cannot exceed the transmit frequency.
 

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mneary

New Member
You will probably receive no help here for a transmitter broadcasting on 20.000 MHz. It is already in use (in USA and elsewhere for time code signals) and we don't want to listen to you interfering.

Change your plans and use a band which is legal for short range communication. We don't care if you only have two crystals.
 

16mofed84

New Member
I do not live in the USA
why no help for transmitter!?

the radio :
from am (530Khz-1.6Mhz)
:
20Mhz
27Mhz
40...
:
:
to fm (88Mhz-108Mhz)

are the 20Mhz is not legal wave??
thank u for reply
 
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