What are the Uses of Capacitor

Introduction: What are the Uses of Capacitor

Capacitor is an electrical device constructed of two parallel plates separated by an insulating material called the dielectric. Lets see What are the Various Uses of Capacitor in detail.

Basic Function

• The basic function of a capacitor is to store energy.
• Common usage includes local energy storage, voltage spike protection, and also complex signal filtering.

Must Read: HOW DOES A CAPACITOR WORKS

What are the Uses of Capacitor

Capacitors have various uses in electronic and electrical systems.

Uses of a Capacitor

Energy storage

A capacitor can store electric energy when disconnected from its charging circuit. Thus it can be used like a temporary battery. Capacitors are commonly used in electronic devices to maintain power supply while batteries are being changed. (This prevents loss of information in volatile memory.)

Power Conditioning

• Capacitors are used in power supplies where they smooth the output of a full or half wave rectifier. They can also be used in charge pump circuits as the energy storage element in the generation of higher voltages than the input voltage. Capacitors are connected in parallel with the power circuits of most electronic devices and also larger systems (such as factories) to shunt away and conceal current fluctuations from the primary power source to provide a “clean” power supply for signal or control circuits.
• Audio equipment, for example, uses several capacitors in this way, to shunt away power line hum before it gets into the signal circuitry. The capacitors act as a local reserve for the DC power source, and also bypass AC currents from the power supply. This is used in car audio applications, when a stiffening capacitor compensates for the inductance and also resistance of the leads to the leadacid car battery.

Filtering

Signal de-coupling

Capacitors pass AC but block DC signals (when charged up to the applied dc voltage). Thus it can be used to separate the AC and DC components of a signal. This method is known as AC de-coupling.

Noise filters, motor starters, and snubbers

Filter & Snubbers

A snubber capacitor across the newly opened circuit creates a path for this impulse to bypass the contact points, thereby preserving their life; these were commonly found in contact breaker ignition systems, for instance. Similarly, in smaller scale circuits, the spark may not be enough to damage the switch but will still radiate undesirable radio frequency interference (RFI), which a filter capacitor absorbs.

Motor Starters

Snubber capacitors are usually employed with a low value resistor in series, to dissipate energy and minimize RFI. Such resistor capacitor combinations are available in a single package. In an inverse fashion, to initiate current quickly through an inductive circuit requires a greater voltage than required to maintain it; in uses such as large motors, this can cause undesirable startup characteristics, and also a motor starting capacitor is used to increase the coil current to help start the motor.

Signal processing

The energy stored in a capacitor can be used to represent information in binary form, DRAMs, or in analogue form. Capacitors can be used in analog circuits as components of integrators or more complex filters and in negative feedback loop stabilization. Signal processing circuits also use capacitors to integrate a current signal.

Tuned circuits

Capacitors and inductors are applied together in tuned circuits to select information in particular frequency bands. For example, radio receivers rely on variable capacitors to tune the station frequency. Speakers use passive analog crossovers, and analog equalizers use capacitors to select different audio bands

Other Applications of Capacitors

Sensing

Most capacitors are designed to maintain a fixed physical structure. Change in capacitance can be used to sense those things.

Changing the dielectric

The effects of varying the physical and/or electrical characteristics of the dielectric can also be of use. Capacitors with an exposed and porous dielectric can be used to measure humidity in air.

Changing the distance between the plates

• Capacitors are used to accurately measure the fuel level in airplanes. Capacitors with a flexible plate can be used to measure strain or pressure. Capacitors are used as the sensor in condenser microphones, where one plate is moved by air pressure, relative to the fixed position of the other plate. Some accelerometers use MEMS capacitors etched on a chip to measure the magnitude and direction of the acceleration vector.
• They are used to detect changes in acceleration, eg. as tilt sensors or to detect free fall, as sensors triggering airbag deployment, and also in many other applications. Also some fingerprint sensors. Additionally, a user can adjust the pitch of a theremin musical instrument by moving his hand since this changes the effective capacitance between the user’s hand and the antenna.
• Changing the effective area of the plates: capacitive touch switches.

Pulsed power and weapons

• Groups of large, specially constructed, low-inductance high-voltage capacitors (capacitor banks) are used to supply huge pulses of current for many pulsed power applications. These include electromagnetic forming, Marx generators, pulsed lasers (especially TEA lasers), pulse forming networks, radar, fusion research, and also particle accelerators.
• Large capacitor banks(Reservoir) are used as energy sources for the explodingbridgewire detonators or slapper detonators in nuclear weapons and other specialty weapons. Experimental work is under way using banks of capacitors as power sources for electromagnetic armour and also electromagnetic railguns or coil guns.

CAPACITOR FAQ

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