This circuit was found in the July 1992 issue of Radio Electronics magazine. The circuit is based on a 741 that activates a buzzer with oscillator. R5 adjusts the sensitivity.
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...