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We want to design a DC power supply with an average DC output voltage of 12 V, allowing a ripple voltage of ±1 V. The load impedance is 200Ω, and we assume a diode voltage drop of 0.7 V when conducting. The rectifier is fed by a transformer with power derived from a line voltage of 120V (rms), 60 Hz (approximating to 170V peak). If a full-bridge rectifier is chosen, sketch the overall schematic, including the transformer and filter capacitor.

User Fogwolf
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Final answer:

To design the specified DC power supply, include a step-down transformer, full-bridge rectifier, and a filter capacitor in the schematic to achieve an average DC output voltage of 12 V with a ±1 V ripple and accommodate for a load impedance of 200Ω, considering the diode voltage drop of 0.7 V.

Step-by-step explanation:

To design a DC power supply with an average DC output voltage of 12 V and a ripple voltage of ±1 V for a load impedance of 200Ω, using a full-bridge rectifier supplied by a transformer with a line voltage of 120V (rms) which translates to an approximate peak voltage of 170V, we need to consider the specifications given. The design will include a transformer to step down the voltage, followed by a full-bridge rectifier to convert the AC voltage to pulsating DC, and a filter capacitor to reduce the ripple voltage. Since the diode drop is 0.7 V, the peak voltage after the rectifier would be 170 V - 2(0.7 V) = 168.6 V. This peak voltage will result in a slightly higher average DC output before filtering. The filter capacitor must be chosen to achieve the desired ripple voltage across the specified load impedance.

A sketch of the overall schematic should include:

  • A transformer connected to the 120V (rms) lines stepping down to approximately 24V (rms)
  • A full-bridge rectifier connected to the transformer's secondary side
  • A filter capacitor connected to the output of the rectifier
  • The load impedance connected across the capacitor
User Uri Meirav
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