Harold in CR
100 kW
The Side Scan Sonar Unit I used to use, searching for logs and such, underwater, had a magnetic switch in the "Fish", towhead. All you did was slide a magnet over the correct location of the switch, and slide it a little, to turn the switch off or on.
That could be added somewhere in a system, to make a hidden "Low-High" circuit.
That could be added somewhere in a system, to make a hidden "Low-High" circuit.