Niobium capacitor
The development of solid electrolyte tantalum capacitors began in the early 1950s as a miniaturized, more reliable low-voltage support capacitor to complement the newly invented transistor. The solution found by R. L. Taylor and H. E. Haring of the Bell Labs was based on experience with ceramics. They ground down tantalum to a powder, pressed this powder into a cylindrical form and then sintered the powder particles into a pellet (“slug”) at high temperatures, between 1500 and 2000 °C, under vacuum conditions. These first sintered tantalum capacitors used a non-solid electrolyte not consistent with the concept of solid state electronics. 1952 a targeted search in the Bell Labs for a solid electrolyte by D. A. McLean and F. S. Power led to the invention of manganese dioxide as a solid electrolyte for a sintered tantalum capacitor.
Induction coil
Michael Faraday discovered the principle of induction, Faraday's induction law, in 1831 and did the first experiments with induction between coils of wire. The induction coil was invented by the American physician Charles Grafton Page in 1836 and independently by Irish scientist and Catholic priest Nicholas Callan in the same year at the St. Patrick's College, Maynooth and improved by William Sturgeon. George Henry Bachhoffner and Sturgeon (1837) independently discovered that a "divided" iron core of iron wires reduced power losses. The early coils had hand cranked interrupters, invented by Callan and Antoine Philibert Masson (1837). The automatic 'hammer' interrupter was invented by Rev. Prof. James William MacGauley (1838) of Dublin, Ireland, Johann Philipp Wagner (1839), and Christian Ernst Neeff (1847). Hippolyte Fizeau (1853) introduced the use of the quenching capacitor. Heinrich Ruhmkorff generated higher voltages by greatly increasing the length of the secondary, in some coils using 5 or 6 miles (10 km) of wire and produced sparks up to 16 inches. In the early 1850s, American inventor Edward Samuel Ritchie introduced the divided secondary construction to improve insulation. Jonathan Nash Hearder worked on induction coils. Callan's induction coil was named an IEEE Milestone in 2006.