Uses for Electrolytic Capacitors

• Electrolytic capacitors are mainly used in power supplies and in portable devices. Monkey Business Images Ltd/Valueline/Getty Images

  Capacitors store electricity. Capacitors consist of two plates (conductors) separated by a thin dielectric (insulator). When electrons are piled on one plate, electrons are driven away from the other plate. If the voltage is then removed from the negative plate the capacitor will hold the charge briefly. Electrolytic capacitors greatly increase the plate size and greatly reduce the dielectric thickness--which greatly improves the amount of charge a capacitor can hold.

Electrolytic Capacitors

• Electrolytic capacitors differ from other capacitors. One of the plates in an electrolytic capacitor is a liquid. The liquid is an electrolyte (an ion bearing liquid that conducts electricity), which is what gives the electrolytic capacitor its name. During the manufacturing process, a thin layer of oxide builds up between the electrolyte and the plate. This thin layer of oxide forms the insulating dielectric. Because the plates are large and the dielectric is thin, the capacity to store electricity is larger in electrolytic capacitors than in any other type. This makes electrolytic capacitors the capacitor of choice when building power supplies.

Aluminum Electrolytic Capacitors

• Aluminum electrolytic capacitors have an aluminum plate and the dielectric is aluminum oxide. This type of electrolytic capacitor is inexpensive and is found in many power supplies. They range in value from 1 farad down to less than a microfarad. They can work voltages up to several hundred volts. They can break down if they go through long periods of no power (the oxide breaks down.) They can be rejuvenated if connected to a power supply and a resistor--the long low current restores the oxide. They are not suitable for working with high frequencies. They also are used in radio frequency amplifiers or anywhere there are high currents and low frequencies.

Tantalum Electrolytic Capacitors

• Tantalum (when correctly processed) forms a spongy material that conducts electricity. When tantalum is the plate of an electrolytic capacitor, the surface of the plate is increased dramatically--and the dielectric is just as thin. This is why tantalum electrolytic capacitors have the greatest capacity of any type of capacitor. Conversely this means that a tantalum of normal capacity can be incredibly small. This is why tantalum capacitors are the capacitor of choice for portable devices such as cell phones, smart phones, portable music players and portable personal computers.

Electrolytic Capacitor Problems

• The main problem with electrolytic capacitors is that they contain a liquid (the electrolyte.) The liquid can dry up--which makes the capacitor stop working. The liquid can leak--which can ruin other components. Another problem with electrolytic capacitors is that they tend to explode if connected incorrectly, they tend to leak current, they have a low temperature tolerance and a short life span.