rf ask modulated data transmitter

Thread Starter

oviniciuslara

Joined Nov 7, 2020
4
Hi everyone,

I'm trying to design a schematic for a RF ASK MODULATED DATA TRANSMITTER, as follows schematic link.

Mainly, the schematic is divided in three blocks:

The first is the digital data simulated by the IC 555 generating square wave at 1.18kHz.
The second is the carrier generated by a tank circuit at 10kHz with a buffer opamp to increase the output impedance.
The third is the modulator that based on the data signal controls if the carrier is HIGH or LOW.

So, I thought that adding a antenna at the transistor collector would work, is this right it? I didn't assembled the circuit yet.

If anyone has suggestion to increase the circuit quality, please share.
 
Last edited:

Sensacell

Joined Jun 19, 2012
2,985
The wavelength of a 10 Khz carrier is 30,000 meters.

Way too low of a carrier frequency to be radiated in any practical way.
 

Ramussons

Joined May 3, 2013
1,228
I would suggest thus:

Make a 1 MHz Crystal controlled oscillator using a couple of NAND gates with a buffer. This will ensure stability.
Make a Class B (or C) transistor amplifier running of 15 volts, with a LC tank on its collector tuned to 3 or 5 MHz. It will radiate much better with a small piece of antenna wire.
The 15 volts will be the output of the 555 as in your original schematic.
 

Deleted member 115935

Joined Dec 31, 1969
0
One thing to remember
most countries have very strict rules on what you can transmit,
power and frequency

are you complirnt.
 
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