MC1496 is modulator and demodulator IC used in AM transmitter and receiver. It is old but popular RF modulator/demodulator, RF mixer, RF frequency doubler IC(Integrated Circuit). In the previous tutorial AM modulator using MC1496 modulator it was shown how the MC1496 AM modulator works with dual power supply. In this tutorial it is shown how to use MC1496 to build AM modulator with single supply. This can be used to build AM transmitter.
The following shows the single supply MC1496 AM RF modulator circuit diagram.
The pins and their meaning is provided below.
As you can see in the above circuit diagram, +5V power supply has been used. The pin 14 is connected to ground. The modulating signal input pins, the carrier signal input pins and the output pins are biased using external resistors. A 0.1uF capacitor is connected to the pin 4. The gain adjust pins 2 and 3 are connected to 1KOhm resistor. A 50K potentiometer is connected across the modulating signal input pins 1 and 4. This is called the carrier null adjustment potentiometer with which we can vary the modulation percentage of the AM signal. The function of these connection was explained in more details in the previous MC1496 Balanced Modulator Demodulator tutorial.
The modulating signal is applied at the input terminal Vs and the carrier signal is applied at the Vc input terminal. The AM signal generated appears at the Vo output terminal. The following shows the AM signal waveform obtained when the input modulating signal is 180mV at 1KHz and the input carrier signal is 60mV at 500KHz.
The following shows the resulting AM signal spectrum.
The frequency spectrum graph shows 500KHz centered carrier signal along lower and upper sideband. This is standard AM signal spectrum. The MC1496 RF modulator IC can also generate Double Sideband Suppressed Carrier (DSB-SC) AM signal which was demonstrated in the tutorial How MC1496 Balanced Modulator Works?.
The following video demonstrates how the single supply MC1496 AM modulator works.
