Found in a 1980s German publication, this circuit tests batteries by type. The circuit is based on a range of LEDs of different colors and is given a table with indications for various voltage ranges.
This common configuration source was obtained from old documentation, so the components can be...
This third-order filter was found in a 1975 publication. The circuit must be powered by a...
This circuit is basically the same configuration as the previous one with a power stage with...