How do the volume controls on a TV work? Is it through some kind of amplitude modification?
Thanks in advance for your answers.
In: Technology
It **is** amplitude modification, although that’s a slightly unusual way to say it. The sound signal coming out of the tuner is rather weak, and can’t easily drive a large speaker. So it goes to an amplifier with variable “gain”. (Or a pre-amplifier with variable gain and an amplifier after that.)
“Gain” is the electrical engineering term for how much the amplitude of a signal is increased by an amplifier. That’s the job of an amplifier…to take a small signal and faithfully increase its amplitude, up to some limit.
The way that the variable control on the amplifier is done can vary. In the old days, it was a part of the circuit containing a variable resistor (a “potentiometer”). The value of the resistance would modify how much gain the amplifier provided.
Nowadays, a lot of this is done digitally instead. Turning the volume knob or using the remote tells a circuit to emit digital pulses to the amplifier controls. These pulses encode either “increase the gain” or “decrease the gain”. How that control is done at the amplifier varies. Typically it changes a reference voltage sent to the amplifier, which in turn controls the gain amount.
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