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
2,821
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
972
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.
 

andrewmm

Joined Feb 25, 2011
1,466
One thing to remember
most countries have very strict rules on what you can transmit,
power and frequency

are you complirnt.
 
Top