Full bridge rectifier (full-wave bridge rectifier, diode bridge or sometimes just simply referred to as bridge rectifier) is something that everyone learning electronics is familiar with and the operating principle is also well understood. But if we could clearly demonstrate how it works in action, it would be even more beneficial.

To demonstrate how a bridge rectifier works, I used four LEDs instead of four diodes to form the diode bridge so that one can easily tell which diodes are conducting and which ones are not. In practice however, LEDs are rarely used as rectifying diodes due to their high forward voltage drop, low current carrying capability and low reverse breakdown voltage.

Another LED is used as the load so that you can clearly see the effect of the rectified waveform.

Because mains frequency is too high for human eyes to discern, I used a signal generator to generate the input waveform at a much lower frequency (e.g. 1 Hz) so that the results can be observed easily. The following short video illustrates and visualizes how a full bridge rectifier works with different input waveforms (sinusoidal and square wave), with and without a smoothing capacitor.

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12 Thoughts on “Visualizing a Full Bridge Rectifier”



  • I’ve got the feeling that the inrush measurement is done by the refresh rate, which is just high enough to catch the value of first µ seconds (208D). So with the 206D one could just take 3-5 measurements and estimate the inrush current as the highest shown during the measurements.

    Just watched your Review and Teardown of a Kaiweets HT208D. No stupid intro, no background noise pretending to be music. Are you sane?

    • In general in-rush current is measured with a time window (the actual method varies depending on brand I have no way of knowing how exactly it was implemented in the 208D). The benefit is that it also hold the value so that you can read it afterwards. For what I do, I rarely needed to measure in-rush current.

  • Sure. One could use the min//max function to hold the value (206D) provided the meter would catch the ‘real’ highest one.
    I’m thinking of buying he 206D since this is locally available for me and the 208D is much more expensive.
    If I do I will let you know how and if it works regarding the in-rush A.
    Anyway thx for Teardown of a Kaiweets.

  • I think I was right about the time/refresh rate. The meter measures A- if it’s inrush or not it makes no difference –
    the meter doesn’t know that-unless there is a little guy inside watching what you are going to do. It just measures in short intervals and 100ms
    isn’t that great – it would be wise to take the measurement 3 times in a row to be sure.

    ‘The measuring time of inrush current is about 100ms.’

    Have a great evening/morning/day/night

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