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Why is a linear power supply called linear ?

A linear power supply is called “linear” due to the linear relationship between the input and output voltages. In this type of power supply, the regulation of output voltage is achieved by varying the resistance or impedance in a linear manner. The core principle involves using a linear regulator circuit, which adjusts the voltage drop across a series pass element to maintain a constant output voltage.

In a linear power supply, the input voltage is usually transformed to a higher or lower voltage using a transformer. Subsequently, the rectified and filtered voltage is fed into a linear regulator. The linear regulator adjusts the voltage by dissipating excess power as heat. The linear relationship between the input and output voltages arises from the proportional adjustment of this voltage drop.

This contrasts with a switching power supply, where regulation is achieved through a more complex process involving high-frequency switching of semiconductor devices. The term “linear” distinguishes this simpler, direct relationship in linear power supplies compared to the non-linear regulation methods used in switching power supplies. The straightforward, proportional adjustment of voltage in response to changes in input voltage is a defining characteristic of linear power supplies.

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