We found this circuit in a 1980s American documentation. The operational amplifiers of the integrated circuit used can be common types in an experimental setup.
In this circuit, suggested by the Motorola Linear Databook of 1990, the resistors depend on the...
This circuit is used for cable checking. We found it in the Radio Electronics magazine of December...
We found this circuit in a 1965 Electronic Design. Transistors are still common but admit...