zaro

What is Linear Power?

Published in Power Supplies 2 mins read

Linear power, in the context of power supplies, refers to a type of power supply that utilizes a transformer to step down AC voltage, followed by rectification and filtering to produce a stable DC voltage.

How Linear Power Supplies Work:

Linear power supplies are characterized by their straightforward design. Here's a breakdown of their operation:

  1. Transformer: An incoming alternating current (AC) voltage is fed into a transformer. The transformer consists of an iron core and coils. The purpose of the transformer is to step down the high-voltage AC to a lower, more usable AC voltage.

  2. Rectification: The lower-voltage AC is then converted into pulsating DC (Direct Current) by a rectifier circuit. This circuit typically uses diodes. The diodes allow current to flow in only one direction, effectively converting the AC signal into a DC signal, albeit an unstable one.

  3. Filtering: A filtering circuit, usually consisting of capacitors, is used to smooth out the pulsating DC voltage. The capacitor stores energy during the peaks of the pulsating DC and releases it during the valleys, thus reducing the voltage ripple and providing a more stable DC voltage.

  4. Regulation (Optional): Some linear power supplies include a voltage regulator to further stabilize the output voltage against changes in input voltage or load current. This regulator uses linear components (like transistors operating in their linear region) to maintain a constant output voltage.

Advantages of Linear Power Supplies:

  • Simple Design: Linear power supplies are relatively simple to design and understand.
  • Low Ripple and Noise: They typically produce very clean DC power with minimal ripple and noise, which is crucial for sensitive electronic devices.

Disadvantages of Linear Power Supplies:

  • Lower Efficiency: Linear power supplies are less efficient than switching power supplies because they dissipate excess energy as heat.
  • Larger Size and Weight: The use of a heavy transformer makes them bulky and heavy.
  • Heat Dissipation: The inherent inefficiency leads to significant heat generation, necessitating heat sinks.

Example Application:

Consider an old audio amplifier. Many older amplifiers utilized linear power supplies because of their ability to provide clean power, crucial for high-fidelity audio reproduction.