We found this circuit in the November 1992 Radio Electronics magazine. The circuit uses an LDR as a sensor and the transistor can be any general-purpose transistor.
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...