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A transformer-rectifier is a combined electrical device that integrates both a transformer and a rectifier into a single unit. It serves the purpose of transforming alternating current (AC) into direct current (DC) while providing the flexibility to vary the input AC voltage.


  1. Voltage Transformation: Like a traditional transformer, the transformer-rectifier component of the device functions to change the voltage level of the input AC signal. It can step up or step down the AC voltage as required by the application.
  2. Rectification: The rectifier part of the device converts the AC voltage into DC voltage by rectifying the alternating current waveform into a unidirectional flow. This process typically involves the use of diodes or other semiconductor devices to allow current flow in only one direction.

Components and Operation:

  • Transformer: The transformer component of the transformer-rectifier unit consists of primary and secondary windings wound around a core. It serves to change the voltage level of the AC signal while providing isolation between the input and output circuits.
  • Rectifier: The rectifier circuitry converts the AC voltage output from the transformer into DC voltage. This can be achieved using various rectifier configurations, such as half-wave, full-wave, or bridge rectifiers, depending on the application requirements.


  1. Power Supplies: Transformer-rectifiers are commonly used in power supply units to convert AC mains voltage into DC voltage for various electronic devices and equipment. They provide a regulated DC output voltage while allowing flexibility in adjusting the input AC voltage.
  2. Variable Voltage Sources: In some applications, the ability to vary the input AC voltage before rectification is desirable. Transformer-rectifiers can provide this functionality, allowing for adjustable DC output voltages while maintaining efficient power conversion.
  3. Industrial and Automotive Systems: Transformer-rectifiers find applications in industrial machinery, automotive systems, and other equipment requiring DC power from an AC power source.


  • Compact Design: Integrating the transformer and rectifier into a single unit reduces space requirements and simplifies installation compared to using separate components.
  • Flexibility: Transformer-rectifiers offer the flexibility to vary the input AC voltage while providing a stable and regulated DC output voltage, making them suitable for a wide range of applications.

A transformer-rectifier combines the functions of a transformer and a rectifier into a single unit, allowing for the transformation of AC voltage into DC voltage while providing flexibility in adjusting the input AC voltage. It finds applications in power supplies, variable voltage sources, and various industrial and automotive systems, offering compact design, efficiency, and flexibility in power conversion.

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