AM modulator using MC1496 modulator(Standard AM)

AM (Amplitude Modulation) is a method of superimposing an information-carrying signal onto a high-frequency carrier signal. The resulting signal can be transmitted over long distances using radio waves. One common method of AM modulation is using the MC1496 modulator, which is a standard integrated circuit that is widely used in electronic design.

 Here is how you can design AM modulator using the MC1496 Balanced Modulator Demodulator IC(Integrated Circuit). The MC1496 or LM1496 are old but useful modulator/demodulator RF IC. They can be used as RF frequency mixer, RF frequency multiplier, modulator to generate SSB(Single SideBand) or DSB(Double SideBand) AM signals, demodulation of SSB or DSB modulated signal, Phase and frequency detector and other RF application. 

The MC1496 modulator is a balanced modulator that uses a carrier signal and a modulating signal to produce an output signal that is the product of the two input signals. The circuit is composed of two balanced modulator sections, each of which is a double-balanced diode ring mixer. The carrier signal is applied to the base of the transistor in one section, while the modulating signal is applied to the base of the transistor in the other section. The output is taken from the collector of the transistor in each section, and these two signals are combined to produce the final output signal. Basically they are used in AM transmitter and receiver. It is useful because it is the fundamental RF modulator/demodulator circuit design that is used in other modern RF modulator/demodulator RF mixer circuit in IC.

The MC1496 modulator is a very versatile circuit that can be used in a wide range of applications. It can be used to modulate a carrier signal with an audio signal to produce an AM radio signal, or to modulate a carrier signal with a video signal to produce an analog television signal. Additionally, it can be used to modulate a carrier signal with a digital signal to produce an amplitude-shift keying (ASK) signal, which is used in many types of digital communications systems. 

A picture of the MC1496 chip is shown below.

 The MC1496 chips used here is PDIP 14 pin IC. The following shows the pin names and their function.

Here we will show how to generate standard AM signal using the same MC1496 chip.

The following shows the circuit diagram of MC1496 amplitude modulator.

In the above circuit, the pins 1 and 4 are for modulating signal input and the pins 8 and 10 are for the carrier signal input. The pins 6 and 12 are for the output. The resistors connected to these inputs and output is for DC biasing of the modulator(that biasing the internal transistor circuitry inside the IC). The pins 2 and 3 are for gain adjust and for adjusting the dynamic linearity of the modulating signal input. The carrier null potentiometer is used here to change the modulation index of the AM signal generated.

The input modulating signal and carrier signal is fed using function generator.

The input signals and the generated output AM signal on oscilloscope is shown below.

The frequency spectrum of the generated output AM signal is shown below.

As can be seen this standard AM signal spectrum with the carrier at center at 500KHz with upper and lower sideband. So the carrier signal is not suppressed in this case. To generate DSB-SC(Double Sideband Suppressed Carrier) AM(Amplitude Modulation) signal with the MC1496 chip see the previous tutorial How MC1496 Balanced Modulator Works?. 

The following video demonstrates how the AM modulator using MC1496 works.

One of the main advantages of the MC1496 modulator is that it is a very simple circuit that is easy to use. It requires only a few external components, such as resistors and capacitors, and can be easily integrated into other electronic devices. Additionally, it is a very reliable circuit that is not prone to failure.

In conclusion, the MC1496 modulator is a widely used and versatile IC for AM modulator, it is easy to use and reliable, it can be used in a wide range of applications from AM radio, analog television and digital communications systems. It is an essential component for any electronic design that requires AM modulation.

AM  modulator can also be build using discrete diodes or transistors. If you are interested in AM transmitter and receiver design and want to learn simple AM modulator design using diodes and transistors see the tutorials AM Transmitter using Ring Diode Modulator and Amplitude Modulation with Emitter Modulator.