Karol Franciszek Pollak was born in south-eastern Poland in 1859. He began working as an electrician, and soon showed great talent for the technology. He went on to manage an electro-technical factory in Berlin. Later became director of a Paris electric tramway company, operating vehicles of his own design. Meanwhile he pottered on an electrochemical battery he subsequently patented under his anglicized name of Charles Pollak.
Charles Pollak’s Borax Electrolyte Aluminum Capacitor
Electrolytic capacitors have positive metal-plate anodes, that form insulating oxide layers through anodization. This increases the thickness of their natural oxide layer, to the extent it becomes the capacitor’s dielectric insulator.
A liquid, solid or gel electrolyte containing ions, covers over this oxide layer becoming the negative cathode plate. This arrangement delivers higher capacitance storage values than ceramic, or film versions.
Charles Pollak discovered the oxide layer on an aluminum anode remained stable in a neutral or alkaline electrolyte, even after he withdrew the external power supply. And so he filed a patent for an ‘electric liquid capacitor with aluminum electrodes’ in 1897.
This method incorporated his own idea of an oxide layer in a polarized capacitor, in combination with a neutral, or slightly alkaline electrolyte. We append a link to the German patent document ‘Elektrischer Flüssigkeitskondesator mit Aluminiumelektroden’ at the end of this article.
Was Karol Franciszek Pollak the Edison of Poland?
Our post would be incomplete if we did not mention this great man’s many other achievements. Warsaw University of Technology awarded him the title of Doctor Honoris Causa in 1925. During his lifespan of 69 years he registered 98 patents.
His most important inventions included a manufacturing method for lead-acid batteries. He also designed commutator and electrolytic rectifiers. Indeed, where would we be today had he not suggested using full bridge diode rectification circuits in 1895? There was definitely more to Charles Pollak than his 1897 borax electrolyte aluminum capacitor!
More Information
The Fitzgerald Paper Capacitor of 1876
An Introduction to the History of Capacitors
Preview Image: Types of Electrolytic Capacitors
