Using operational amplifiers of the time, we found this circuit in documentation from the 90s. The configuration can be adapted to use modern operational amplifiers.
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...