Radio circuit diagrams electronics projects for radio transmitter, radio receiver circuit, rf amplifiers, rf boosters and some other related RF circuits like: fm antenna booster, microwave transmitter and wireless modules.
Using BA1404 can be designed a very simple and useful stereo fm stereo modulator electronic project . This BA1404 fm stereo modulator device works in FM broadcast band ( 75- 108MHz) and require few external common components .
The BA1404 fm stereo modulator Ic contains all parts needed to design an simple high efficiency stereo transmitter circuit , it contains a stereo modulator that creates stereo composites signals ,an FM modulator that creates FM signals and a RF amplifier .
The fm stereo transmitter develops composite signals made up of a main(L+R) signal and sub(L-R) signal and a pilot (19KHz) signal using a 38KHz crystal oscillators.
The RF amplifier transmits the stereo encoded signals and is also a buffer for FM modulator .
For this FM stereo transmitter circuit you’ll need a DC power supply that can provide an output voltage between 1.5 an 3 volts . This fm stereo transmitter circuit project can be used for FM stereo transmitters or wireless microphone circuits .
The L1 coil must have 3 turns of 0.5mm wire on a 5 mm core .
Antenna used in this transmitter can be an common telescopic antenna or a 60-80 mm long Cu wire .
A very simple FSK demodulator for (the 2025 Hz and 2225 Hz) electronic project can be designed using the LM565 which is a general purpose phase locked loops IC containing a stable, highly linear voltage controlled oscillator for low distortion FM demodulation, and a double balanced phase detector with good carrier suppression.
The VCO frequency is set with an external resistor and capacitor, and a tuning range of 10:1 can be obtained with the same capacitor.
As you can see in the circuit diagram , this FSK demodulator require extreme few external components .
As we mentioned , this circuit is an FSK demodulator for the 2025 Hz and 2225 Hz , but you can change the parameters , by changing the loop filter components .
This demodulator circuit needs to be powered from an external 12 volts DC power supply .
