I remembered seeing that cartoon somewhere, so I looked it up. It is good to "Lighten-Up" when one gets too serious, isn't it?
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A full-wave rectifier uses both halves ot the 60Hz input flipping the negative phase of the sine wave to create a 120Hz positive-going input to the power supply filter capacitors. * These are not square pulses with high harmonic content though. https://electronicscoach.com/full-wave-rectifier.html Darn it! I wish I knew how to post a image directly! Oh! Vacuum tube rectifiers like 5U4/ 5AR4 are full-wave. |
Sisyphus, thanks for providing the link. However, firstly, let’s not use the term "pulses." That would imply a squarish waveform, which is not what is being referred to. What is being referred to are the portions of a 60 Hz sine wave that approach and include its positive and negative peaks. Secondly, and more significantly, the reference you provided does not address what happens **after** the rectifier bridge. As noted earlier by you and also in one of Ralph’s posts that I quoted there are capacitors, which smooth the waveform into a close approximation of DC and also store energy, that stored energy being what powers the downstream circuits. And as Ralph explained earlier the rectifier diodes will only conduct when the instantaneous voltage of the AC supplied by the power transformer exceeds the voltage stored on the capacitors. Or, more precisely, when the instantaneous AC voltage exceeds the voltage stored on the capacitors by the relatively small amount that is necessary to turn the diodes on (which is approximately 1.4 volts in the case of a typical full-wave solid state bridge rectifier circuit). And assuming the rectification circuit is full-wave, that will only happen when the AC voltage supplied by the power transformer is approaching either a positive or a negative peak. In other words, for just a relatively small fraction of the 60 Hz period. During the rest of the 60 Hz period the rectifier diodes will be back-biased and unable to conduct. Therefore AC current will not be drawn continuously, but rather for just a fraction of each cycle. In other words, the AC current which restores charge to the capacitors is drawn in narrow "spikes," with "spikes" being defined per the first paragraph in this post. As Ralph, I, and Elizabeth have all maintained. In any event, thanks for providing the chuckle of the day with the "duty calls" cartoon :-) Regards, -- Al |
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