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.
This circuit that uses only transistors indicates when the voltage in the circuit has the voltage...
This power supply makes use of a capacitance multiplier. C2 can be 100 uF which with the action of...
Found in an English publication from the 70's, this radio uses a germanium transistor and requires...