This circuit from the 90s, found in an Electronic Engineering can be used as a shield since its control is digital with TTL logic of 5 V. The components used are still common today.
This circuit, from a publication in the 1970s, uses transistors that no longer exist, but can be...
This circuit tests the earth connection in computer outlets and other equipment that requires this...
The gain of the Operational Amplifier in the figure is given by the ratio between R1 and R2. In...