I recently had an Amazon 5V/1A device charger pack up, these things happen. I didn't intend to repair it, it's not worthwhile, but I cut it open to inspect the innards. As suspected, there was a small capacitor leaking and dead. As always I am impressed with how few components they use. There are 2 transformers, one smaller than the other, a few capacitors, one transistor and 2 diodes I could see. That's it, for a decent quality 5V/1A PSU. It's a "how do they do it so cheaply?" product.
I'm intrigued as to a typical schematic. I know that the general principle is that the incoming mains is switched on and off by a circuit controlled by a high frequency oscillator, this then generates a very rough on-off wave akin to a square wave, and this is then smoothed to some approximation to DC. The mark-space ratio dictates the final voltage. That's as much as I know. Does anyone have a more comprehensive explanation? I'm particularly intrigued by the need for 2 trafos, one of which is tiny, like a bucking trafo might be.
I'm intrigued as to a typical schematic. I know that the general principle is that the incoming mains is switched on and off by a circuit controlled by a high frequency oscillator, this then generates a very rough on-off wave akin to a square wave, and this is then smoothed to some approximation to DC. The mark-space ratio dictates the final voltage. That's as much as I know. Does anyone have a more comprehensive explanation? I'm particularly intrigued by the need for 2 trafos, one of which is tiny, like a bucking trafo might be.