This circuit was taken from Maxim documentation from the 1990s. It can be implemented on the basis of modern operational amplifiers. Power supply doesn't have to be symmetrical.
In the figure we have a simple signal tracer circuit to be coupled to the volume control of an AM...
This circuit was found in documentation from the 90s, using components from that time. The...
This circuit, obtained from old documentation, allows the recovery of sulfated batteries. The...