 # General: Peak Inverse Voltage

## What is the peak-inverse-voltage across the rectifier in a half-wave power supply?

A. One-half the normal peak output voltage of the power supply
B. One-half the normal output voltage of the power supply
C. Equal to the normal output voltage of the power supply
D. Two times the normal peak output voltage of the power supply

[G7A04]

To answer this we must know what is going on in a half wave power supply.

A half-wave rectifier takes, as you might suspect, only half of a given alternating current (AC) input voltage, and turns that into (alright, well, sort of) direct current (DC.)  The above image shows what that basically looks like.  In this instance, it takes the positive voltage and discards the negative voltage.

The peak inverse voltage is the maximum input AC voltage that the device can withstand before it is operating outside of specifications, possibly even to the point of damage.  In a half-wave power supply, we are discarding one half of the wave, so it must be able to take a peak-to-peak input voltage of at least twice its output.

The answer then, is D. Two times the normal peak output voltage of the power supply.

### 1 thought on “General: Peak Inverse Voltage”

1. Sorry – This one perturbs me 🙂

The schematic needs a capacitor (or more diodes) for the rectifier’s reverse voltage to approach 2x V peak.

As it stands, seems to me the answer should be V peak, instead.

Can you guys please supply some words to justify / explain the FCC given answer?

Really impressed with your site’s presentation. Very nice!