If this question was posted before, please let me know. I searched for "how does a bridge rectifier work" and did not find an answer.

The part that I especially find confusing is when I have the four diodes in such a way and how each reacts to the incoming AC.

  • \$\begingroup\$ See here. \$\endgroup\$ – Shamtam Feb 17 '15 at 3:10

A simple bridge rectifier circuit is as shown :

enter image description here

During the positive half cycle, diodes D2 and D3 are forward biased and D1 and D4 are reverse biased. Hence the direction of flow of current is D2 -> Load Res -> D3.

During the negative half cycle, the diodes D4 and D1 are forward biased while D2 and D3 are reverse biased. Hence the direction of flow of current is D4 -> Load Res -> D1.

An important point is that the direction of current is the same ie from right end to left end through the resistor, and hence the polarity of voltage obtained does not change.

You can find additional details here :


  • \$\begingroup\$ Yes. I now get it. Thanks and my bad about double posting. \$\endgroup\$ – gp443 Feb 17 '15 at 3:17

This is not only an ordinary circuit idea; this is a general topology idea (for example, in this way a one-way street in your city can be realized). Think of the four diodes as switches that commutate the current through the load so that to make it unidirectional. If you replace the ordinary diodes with LEDs, you can see in an attractive way how this circuit works. See for example how my students conducted this LED experiment in the laboratory.

Full-wave diode bridge visualized

  • \$\begingroup\$ Nice. What was tripping me up was I couldn't visualize how the voltage was flowing, especially the AC. But your example is actually even more visually illustrating (I'm the kind of person that needs a picture to understand.) \$\endgroup\$ – gp443 Feb 17 '15 at 12:14
  • \$\begingroup\$ Then visit my site of circuit-fantasia.com where electrical quantities are visualized, animated and even sounded (see, for example, the movie about op-amp inverting summer). BTW the current is what flows; the voltage is the "pressure" that makes the current flow. \$\endgroup\$ – Circuit fantasist Feb 17 '15 at 15:40

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