(AI translated)
For my latest collection exhibit, I decided to upgrade the power supply – to create something like the LM2596 from an overclocked 7805…
Before the postal service went crazy, I bought the cheapest PCBs with counterfeit LM2596ADJ from several suppliers: LM2596 modules from China (photo enlarges, you can look at the chip logos)
To test, I connected them all with the same load (about 33 ohms) and adjusted them to 5V. Input voltage 13V. Some modules operated at around 50kHz frequency – likely an analog of a weaker chip (LM2576?). Others worked at the correct frequency – around 150kHz, though perhaps a bit more.
One module worked very strangely:
So I removed the chip and connected a salvaged (and maybe original, National-made LM2596S ADJ). I’m not sure about this chip, the inscription looks very unprofessional, but the PCB was assembled in Lithuania and used in some industrial computer. I also replaced the diode. I wanted to use a really original chip, the one nearby in the first photo, but I needed an ADJ.
Oscillograms of all modules. The calculations in the document mean almost nothing because the load is very small. However, if it is the LM2576, the inductance for this chip is probably too small.
