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Hello this is my first post. This is my thought process:

I can use the following equations to calculate the theoretical ripple factor for a full wave rectifier:

enter image description here

Through simplifying, it can be rearranged to give a constant ripple factor of 0.483. enter image description here

Now, I built a said full wave bridge rectifier with no filters with a breadboard, the input AC source is 2vpp (amplitude of 1v) @ 500 Hz, resistor is 1kOhm, and 4 diodes. This is the circuit:

enter image description here

Using an oscilloscope, I have measured the signals: enter image description here enter image description here

How can I use my measured values to calculate an experimental ripple factor value? It does not seem as simple as doing Ripple Factor (Rf) = Vac/Vdc. If I do 1/2.01 this gives a value close to but it does not make sense that Vac would be 1v and Vdc would be 2.01v? I have tried consulting other info online but it all seems to be theoretical.

I feel like I am missing something crucial as I have spent a lot of time trying to figure this out and have not made any progress. I'm at the point wondering if there is no such thing as an experimental ripple factor and it is just always constant? Any help is greatly appreciated.

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  • \$\begingroup\$ What are the scope signals from i.e. what nodes are they connected to? Please redraw your circuit using the tools provided. \$\endgroup\$
    – Andy aka
    Oct 7, 2023 at 21:13

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You have made the same error asked before but could not find a similar question right now.

Your generator and scope are not isolated, they are both referenced to mains earth, so scope ground and generator ground short out one diode and clamp out one half of the waveform.

But anyway, if you have a full wave rectified sine wave, and assuming ideal diodes, the peak voltage versus average DC will have a fixed value.

The errors in practice come from the fact that you are using input amplitude o 1V and diodes are not ideal but remove about 0.7V forward voltage drop so the difference is significant.

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  • \$\begingroup\$ Hm ok thank you. This is slightly disappointing news as it's how the example circuit and oscilloscope readings look in our lab manual and our TA checked our setup gave it the ok. Also if relevant I ran the circuit at an input amplitude of 2v and got similar results. Suppose I had your case with the "full rectified sine wave, assuming..." Is there any point in proving this in reality as Vac and Vdc are functions of Vm and just cancel out/is there any case where I would get a different ripple factor (ideal vs exp.)? It now seems to me ripple factor is just dependent on the rectifier design. \$\endgroup\$
    – MatRanc
    Oct 7, 2023 at 21:11

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