I built a variable power supply from an old laptop power supply and a buck-boost converter module.
Building a Variable Power Supply using Buck-Boost Converter Module and Old Laptop Power Supply

I built a variable power supply from an old laptop power supply and a buck-boost converter module.
Someone cut off and throw away a perfectly good wall wart.
Old speaker, broken capacitor.
Arduino controlled DIY electronic load.
Two crappy breadboards make one slightly more convenient — but still crappy — large breadboard.
Old printer, new frustation.
DSO150 stops showing waveforms. How could it be?
Testing the ACS712 when no current is flowing.
Reading ACS712 analog output using Arduino UNO.
I2C works okay for both STM32F103C8T6 and CS32F103C8T6.