WEBVTT

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Switching power supply with step-down filter

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Description of the connections, as shown in the diagram in the following screen!

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The oscilloscope displays the rcy variable duty cycle, the green multimeter: the ratio:%

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We are at 0; 0 V output: yellow multimeter

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Approximately 25%

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At 25%, one observes well 1/4 of the output Ue: 20/4 = about 5 V (4.78)

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At 50% of rcy, one obtains 50%, 1/2 of the 19.7 V at Us: 9.88 V

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Same as 75%: 3/4 of Ue: Us = about 15 V for 20 V in Ue

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And up to 100%!

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Osillo is now on, the parasite is observed due to commutation, here rcy = 62%

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The oscilloscope on Us shows us the DC voltage Us measured with the yellow multimeter

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The noise will be addressed in EMC, the capacitor will be removed to see the unfiltered signal Us

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We observe the charge and discharge of the coil!

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The signals demonstrate the behavior of the inductance of the coil!

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I added an ammeter and a 12 V 21 W bulb as a charge for Us

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Ue is 20 V, I regulate the rcy so as to circulate Is = 1 A, here obtained for 25% of rcy

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If we have almost 1 A (0.95) output, Ie, provided, is only 0.25 A!

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Here! 0.25 A is 25% of 1 A ... As the duty cycle!

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And at 50% of rcy, we have about Ie = about 50% of Is provided ...

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As for a self-transformer: Us / Ue = Ie / Is!