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I was reading this article https://www.etechnog.com/2018/06/How-mobile-charger-works.html and I was wondering how can I search and buy the specific transformer that AC-DC converters use to step down the high-voltage, high-frequency AC to 5 VAC, 12 VAC, etc.

I can't seem to find them in Amazon just in wholesale Alibaba and I just need a couple for learning and testing purposes. I know that off-the-shelf 5VDC, 9VDC, etc. wall adapters and DC-DC converters exist, but I want to build and test one of those myself.

ocrdu
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Smaug
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  • I suggest a different sequence. Buy one , reverse engineer it and test it fully, write specs, then learn design concepts and how to measure inductance at 10% saturation. – Tony Stewart EE75 Jul 05 '22 at 23:12
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    Don't buy electronic components off Amazon or Alibaba. – DKNguyen Jul 05 '22 at 23:13
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    The term "220VAC - 5VAC transformer" heavily implies a transformer that works at line frequency. You're trying to understand an off-line switching power supply. I suggest that (B) you start with that term, or (A) you start by understanding simpler switching supply circuits (like a 12V to 5V converter), and then once you have actually build something that works you work your way up to off-line devices. – TimWescott Jul 06 '22 at 01:16

1 Answers1

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A "high frequency" transformer in a switching converter would be acting as the switching inductance. These having high frequency DC currents (via rectifier) switched through them and are acting in a switched DC-DC fashion. Therefore, they would not be specified as "220VAC-5VAC" because it is not being used in a normal sinusoidal AC-AC conversion and because VAC implies mains frequencies of 50/60Hz.

Unless you're talking about a transformer with rectifier and smoothing cap that sits ahead of the switching circuitry to produce a lower voltage DC so the switching converter can work with it more easily, in which case it is not in a high frequency position since it runs at mains frequencies.

So you have anachronistic specifications. That's why you can't find anything.

Maybe don't try working with mains voltages until you know what you're doing. But a sealed, pre-made supply of some sorts that produces a low voltage from the mains and work with that.

DKNguyen
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