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Transistor AM Modulator Circuit Diagram

Posted by merzaha gulhku Saturday, August 3, 2013 0 comments

is the process of changing some characteristics (e.g. amplitude,
frequency or phase) of a carrier wave in accordance with the intensity
of the signal is known as modulation.

The figure shows the electronics circuit of a simple am modulator. It is essentially a CE amplifier
having a voltage gain of A. The carrier signal is the input to the
amplifier. The modulating signal is applied in the emitter resistance

The carrier ec is applied at the input of the amplifier and the modulating signal es
is applied in the emitter resistance circuit. The amplifier circuit
amplifies the carrier by a factor A, so that the output is Aes. Since the modulating signal is a part of the biasing circuit, it products low frequency variations in the emitter circuit. This in turn causes variations in “A”.

The result is that amplitude of the carrier varies in accordance with the strength of the signal. Consequently, amplitude modulated output is obtained across RL. It may be noted that carrier should not influence the voltage gain
A; only the modulating signal should do this. To achieve this
objective, carries should have a small magnitude and signal should have a
large magnitude.