Found in an American publication from 1969, this circuit can be adapted to be used as a shield. Operational amplifiers can be of modern equivalent types.
In the figure we have the way to increase the current capacity of an operational amplifier. The...
We found this circuit in a 1982 documentation, but the circuit can still be easily assembled, as the...
Found in an Electronics World of 1968 this circuit can use any SCR and diodes depending on the...