We found this circuit in the July 1969 Radio Electronics magazine. The circuit uses a coupler made with a lamp and an LDR. The power of the lamp determines the types of diodes.
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...