This high impedance circuit was found in 1967 documentation by Ferranti. The original operational amplifier is from that time. The circuit can be implemented with modern equivalents.
This circuit was found in a 1962 publication. At the time there were high voltage batteries like the...
Found in documentation from the 1980s, this highly sensitive circuit is based on the conduction by the...
In the figure we have the way to implement a power zener diode. The voltage depends on the zener,...