What is the formula for Bridge Rectifier Peak Output?

The Bridge Rectifier Peak Output formula is Vdc(peak) = Vpeak − 2 × Vdiode, where Vdc—Peak DC at the reservoir capacitor (V); Vpeak—Peak secondary voltage = √2 × Vrms (V); Vdiode—Forward drop per diode (~0.7–1 V).

What does Vdc mean in the Bridge Rectifier Peak Output formula?

Vdc is Peak DC at the reservoir capacitor (V).

Bridge Rectifier Peak Output

Q: How do you calculate Bridge Rectifier Peak Output?

Use the formula Vdc(peak) = Vpeak − 2 × Vdiode. In a full bridge rectifier with a reservoir capacitor, two diodes conduct in series on each half cycle, so the capacitor charges to the transformer peak voltage minus two diode drops. Enter the values you know in the calculator above and it solves for the remaining variable.

Vdc = Vpeak − 2 · Vdiode

Calculator

DC Output (peak)

Transformer Peak

Diode Drop

Result

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Formula

Vdc(peak) = Vpeak − 2 × Vdiode

Description

In a full bridge rectifier with a reservoir capacitor, two diodes conduct in series on each half cycle, so the capacitor charges to the transformer peak voltage minus two diode drops. This peak value, not the averaged Vdc, is what a capacitor-input filter actually delivers under light load. It sets the no-load output and the voltage rating of downstream components.

Variables

Vdc — Peak DC at the reservoir capacitor (V)
Vpeak — Peak secondary voltage = √2 × Vrms (V)
Vdiode — Forward drop per diode (~0.7–1 V)

Practical Notes

Use ~1 V per diode for ordinary silicon at current, or ~0.4 V for Schottky. Under load the average output drops below this peak by the ripple; size the transformer for the loaded, not the no-load, voltage.

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