This 10 A solid state relay was found in a 1980s documentation. It can work as a shield and implemented with modern equivalent transistors.
This simple circuit uses a 200 µA galvanometer to measure voltages in three ranges. The circuit...
Some delicate sensors such as reed-switches and even sensors made with small metal plates do not...
We found this circuit in a 1968 Electronics World. The potentiometer should be set to trigger the SCR...