This circuit was found in an American documentation from the 1980s. The circuit combines filters of different types in a single structure, each of which can be programmed for a frequency.
Found in National Semiconductor documentation from the 1980s, this circuit uses an operational...
This basic voltmeter circuit has an input resistance of 2 M. The instrument is 100 uA and the...
This simple alarm using only transistors was found in a 1990 publication. It can be powered by D...