Re: the gutless, bloated, and fried power supply hall of shame
Dang, what a piece of garbage!
I also have never quite seen a design like this before.
It's flyback, of course. And it appears to have feedback, as evident from the optocoupler. But generally designs like that use 2 transistors: a bigger one for driving the transformer and a smaller one for driving the bigger transistor. This one has only ONE transistor doing everything on the primary side. I initially even confused it with one of those single-transistor oscillator designs with no feedback. Then again, it appears there is no difference between this one and the one-transistor oscillator designs when it comes to regulation... or lack thereof, I mean.
If the output caps are good and that thing is still only outputting only 3V with ~100 mA load, then it surely belong to the scrap pile. I mean, with such poor loading, you'll be lucky if you can power more than a few LEDs with this thing. Heck, if you remove the case LEDs, you can probably almost double the adapter's output capacity.
Originally posted by Hemingray
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I also have never quite seen a design like this before.
It's flyback, of course. And it appears to have feedback, as evident from the optocoupler. But generally designs like that use 2 transistors: a bigger one for driving the transformer and a smaller one for driving the bigger transistor. This one has only ONE transistor doing everything on the primary side. I initially even confused it with one of those single-transistor oscillator designs with no feedback. Then again, it appears there is no difference between this one and the one-transistor oscillator designs when it comes to regulation... or lack thereof, I mean.
If the output caps are good and that thing is still only outputting only 3V with ~100 mA load, then it surely belong to the scrap pile. I mean, with such poor loading, you'll be lucky if you can power more than a few LEDs with this thing. Heck, if you remove the case LEDs, you can probably almost double the adapter's output capacity.
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