Below is a list of Induction Coils manufacturers from Cary, Illinois. An induction coil is a type of disruptive-discharge electric coil. It is used to transform low voltages of direct current flow into high-voltage pulses or a high-voltage alternating current flow. Induction coils were originally developed in 1836 and were previously known as Ruhmkorff coils, although they were actually invented by a man named Nicholas Callan.