How to Check a Bridge Rectifier

By Emilio Ormez
An unrectified AC signal switches polarity, positive and negative values
electrical signals image by Albert Lozano from

Most electronic equipment requires a direct current (DC) input, meaning that the alternating current (AC) power from the wall must be rectified before it can be used. A bridge rectifier, or full-wave rectifier, is a simple circuit made up of four diodes. Its output maintains the same polarity, regardless of the polarity of the input voltage. To check that a bridge rectifier is working properly, it must be verified that the polarity of the output does not change when the polarity of the input is reversed.

Using a Battery

Connect battery to input leads of bridge rectifier circuit.

Measure the output voltage of the circuit using a multimeter or oscilloscope.

Reverse the battery. If the output is unchanged and nonzero, the circuit is working.

Using an Oscillating Voltage Source

Connect the oscillating voltage source (transformer or function generator) to the input leads of the circuit.

Using a multimeter, measure the output voltage. For a sinusoidal input signal, it should read roughly 0.6 of the amplitude of the input, the average value of the rectified sine curve.

If using a transformer, you can observe the rectified waveform on an oscilloscope. Connect the oscilloscope to the output leads of the rectifier. The rectified waveform should look like the absolute value of a sine curve, or a series of "hills."

About the Author

Emilio Ormez started writing professionally in 2010. In addition to his fiction writing, Ormez enjoys exploring a range of topics, including physics, technology, outdoor sports and travel. He holds a Bachelor of Arts in physics from a liberal arts college.