Tipos de Condensadores o capacitores y aplicaciones. (Clase 17.1 curso electronica)

Introduction to Capacitors

Overview of Capacitor Types

• The lesson introduces various types of capacitors found in electronic circuits, emphasizing the importance of sharing the content on social media for broader reach.

• Capacitors are classified based on the dielectric material used in their construction, including aluminum, tantalum, ceramic, and plastic types.

Electrolytic Capacitors

• Electrolytic capacitors have a high capacity-to-volume ratio; they consist of two conductive plates separated by an electrolyte-soaked paper dielectric.

• These capacitors exhibit polarity; the positive terminal must be at a higher potential than the negative. Reversing polarity can lead to overheating or explosion.

• It's crucial to know the rated DC voltage indicated on electrolytic capacitors; exceeding this voltage can cause failure and potential hazards.

Applications and Characteristics

• Electrolytic capacitors are versatile and used for energy storage, timing delays, signal filtering, and coupling in amplification stages while operating under DC conditions.

• Aluminum electrolytic capacitors can achieve capacities from 0.1 µF to 100,000 µF with tolerances ranging from -10% to +50%.

Risks and Precautions

Connection Guidelines

• Proper connection is essential; the longer lead indicates the positive terminal which should connect to a higher potential than the negative marked with a minus sign.

Failure Modes

• A common failure mode occurs when internal insulation dries out over time due to humidity loss, leading to increased volume as seen in damaged units.

Tantalum Capacitors

Advantages and Risks

• Tantalum capacitors feature thin insulating layers allowing for higher capacitance per unit volume but pose significant risks if voltage ratings are exceeded—leading to explosions or short circuits.

Reducing Risk with Series Connections

Configuration Techniques

• To mitigate risks associated with electrolytic capacitors, connecting two identical capacitors in series reduces effective capacitance by half while maintaining voltage ratings.

Metalized Plastic Capacitors

Construction and Types

• Metalized plastic film capacitors consist of plastic films coated with thin metal layers. They come in various types such as K-type (polystyrene dielectric) and MK-type (polypropylene dielectric).

Applications

• These types are commonly used in telecommunications equipment and oscillators due to their high insulation resistance suitable for elevated voltages.

Key Features of Metalized Plastic Capacitors

Performance Characteristics

Electric Arc and Capacitor Regeneration

Electric Arc Formation

• An electric arc forms at a point with a high potential gradient, generating thermal energy that can vaporize surrounding metal. This process isolates the damaged point from the electrical circuit while allowing the capacitor to remain operational.

Capacitor Characteristics

• The metallic surface involved in self-regeneration is minimal, resulting in negligible capacitance variation. Only a small fraction of the stored energy in the capacitor is dissipated during this brief process lasting about 10 microseconds.

Types of Ceramic Capacitors

• Ceramic capacitors use ceramic as their dielectric material. The most common types are single-layer or disc capacitors, which consist of a ceramic insulating disk with high dielectric constant, metallized on both sides.

• These disc capacitors range from 2.2 picofarads to 0.22 microfarads and typically operate at low voltages (up to 63 volts), although higher voltage variants exist for special applications up to 2000 volts.

Multi-layer and Mica Capacitors

• Multi-layer ceramic capacitors have capacitance values ranging from one picofarad to ten microfarads and are known for their compact size and efficiency.

• Mica capacitors are high-quality components that offer excellent stability and precision, with minimal capacitance change over time; however, they come at a higher cost.

High-Efficiency Capacitors

• High-efficiency volumetric capacitors provide capacities 10 to 50 times greater than electrolytic capacitors while maintaining a small size due to lower maximum working voltages (around 55 volts). They are also referred to as supercapacitors or double-layer capacitors.

Variable Capacitance Capacitors

• Variable capacitance capacitors allow adjustable capacity ranging from 25 picofarads to 22 picofarads with a nominal voltage rating of 150 volts. These trimmer capacitors come in various shapes and sizes.

• Air-dielectric variable capacitors were historically used in tuning circuits (e.g., radio dials), adjusting capacitance for resonance with radio frequencies but have largely fallen out of use due to modern alternatives like diodes.

Summary Table of Capacitor Types