This high impedance amplifier is from 1985 documentation by General Electronic. The amplifier with FET at the entrance is from the period and the source is 9 V.
This circuit, from a 2002 documentation, checks the logic levels of the inputs, providing a...
Using a dual 555 CMOS this very useful circuit on the bench was found in the July 1998 Electronics Now...
The integrated circuit used in this regulator is quite old. Its 1970s casing is still made of...