Capacitors are components that are used to store
an electrical charge and are used in timer circuits. In this project, the
capacitor may be used to produce a timer and filter. Sometimes capacitors are
used to smooth a current in a circuit as they can prevent false triggering of
other components such as relays. When power is supplied to a circuit that
includes a capacitor – the capacitor charge up. When power is turned off the
capacitor discharges its electrical charge slowly.
A
capacitor is a little like a battery. Although they work in completely
different ways, capacitors and batteries both store electrical energy. A
battery has two terminals. Inside the battery, chemical reactions produce
electrons on one terminal and absorb electrons on the other terminal. A
capacitor is much simpler than a battery, as it can't produce new electrons - it only stores them. Inside the capacitor, the
terminals connect to two metal plates separated by a non-conducting substance, or
dielectric. We can easily make a capacitor from two pieces of aluminum foil and
a piece of paper. The dielectric can be any non-conductive substance. However,
for practical applications, specific materials are used that best suit the
capacitor's function. Mica, ceramic, cellulose, porcelain, Mylar, Teflon and
even air are some of the non-conductive materials used. The dielectric dictates
what kind of capacitor it is and for what it is best suited. Depending on the
size and type of dielectric, some capacitors are better for high frequency
uses, while some are better for high voltage applications. Capacitors can be
manufactured to serve any purpose, from the smallest plastic capacitor in your
calculator, to an ultra capacitor that can power a commuter bus. NASA uses
glass capacitors to help wake up the space shuttle's circuitry and help deploy
space probes. Here are some of the various types of capacitors and how they are
used.
•Air - Often
used in radio tuning circuits
•Mylar - Most
commonly used for timer circuits like clocks, alarms and counters
•Glass- Good for
high voltage applications
•Ceramic
- Used for high frequency purposes like antennas, X-ray and MRI
Machines
•Super capacitor –
Powers electric and hybrid cars6
