A fish shocker was once a relatively popular way to harvest large numbers of fish from streams, rivers, ponds and lakes. Fishermen often used the magnetos from hand-crank telephones to provide the electrical power for the shocker, scooping up all the fish they wanted as the stunned fish floated to the surface. The practice is now illegal in many states except when done by licensed fish biologists, who use the shocker to estimate and evaluate fish populations under carefully controlled conditions. You can still find parts for making a fish shocker, though you must find a legal place to use it.
Find the positive and negative posts on the rear of the magneto.
Cut the #10 stranded wire into two 15-foot lengths. Strip 2 inches of the insulation off one end of the two 15-foot lengths. Attach the stripped end of one wire to the magneto's negative post and the stripped end of the other wire to the magneto's positive post. Strip about 10 inches of insulation off each wire's trailing end.
Row the boat to an area where fish are likely to school or hide. Drop one wire over one side of the boat and the other wire over the opposite side of the boat. It's best to have at least two people for successful "electrofishing" (taking fish with a fish shocker).
Crank the magneto, being careful not to touch any area near the rear of the magneto, where electricity is generated. A telephone magneto can generate 8 to 110 volts of electricity, depending on the size of the magneto and how fast you crank. Stop cranking as soon as you see fish rising to the water's surface. Have your companion scoop them up with the net.
Instruct your companion to scoop quickly, because once you stop cranking and generating electricity, the fish recover and swim away. Experiment with the speed and duration of cranking required to generate the right amount of current to bring fish to the surface. A wooden boat is less likely to conduct current from the water than an aluminium boat.
Don't touch the water while you're shocking the fish. While the amount of current may not be enough to seriously hurt you, it can still deliver an unpleasant shock. Check local regulations for legal species, limits and places for fish-shocking. Most sports fishermen condemn this method of catching fish. If you choose this method, you won't make any friends among fishermen who respect the sport.