The other day, out of curiosity I was measuring the current wave shape of a laptop charger. The wave shape indicated a spike only in one half cycle. I'm guessing half wave rectifier here.

One thing that kept me thinking was Why would someone prefer a half wave over full bridge and full wave rectifier? I'm guessing lower BOM cost / the 1.4V drop across the diodes.

Or was it just the designers choice and there's no point in thinking about it ?

  • \$\begingroup\$ Possible duplicate +1, your answer there has everything in it. \$\endgroup\$ Feb 2, 2016 at 18:30

1 Answer 1


There are a few good reasons: -

  • Only one diode forward voltage drop
  • Only one diode as opposed to four
  • 0V can be an incoming power line as well as the outgoing DC side
  • You can use one secondary of a transformer and two diodes to get a split V, 0, -V supply: -

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