Electronics Circuit Fundamentals

Vacuum

Space devoid of charged particles like electrons, protons, and neutrons.

Conductance

Reciprocal of resistance, measured in siemens or mhos.

Vacuum Tube

Electronic device controlling electron flow in a vacuum.

Thermionic Emission

Release of charged particles from a heated metal surface.

Advantages of Vacuum Tubes

Easy replacement, high-temperature tolerance, superior sound quality.

Disadvantages of Vacuum Tubes

Large size, heat generation, high voltage requirement, high power consumption, high cost, high failure rate, and space occupation.

Vacuum Diode

Simplest vacuum tube with cathode and anode.

Vacuum Triode

Vacuum tube with cathode, anode, and control grid for signal amplification.

Vacuum Tetrode

Vacuum tube with four electrodes: cathode, anode, control grid, and screen grid.

Vacuum Pentode

Vacuum tube with five electrodes: cathode, control grid, screen grid, suppressor grid, and plate.

Gas-Filled Tube

Tube operating by ionizing gas with applied voltage.

Noble Gases

Helium used in helium-neon lasers, neon in high-power fluorescent tubes.

Semiconductors

Branch of physics controlling electron flow in circuits.

Atomic Number

Number of protons in an element's nucleus.

Valence Electrons

Electrons in the outermost shell of an atom, loosely bound.

Ionization

Process where atoms lose valence electrons upon absorbing energy.

Electron Configuration

Arrangement of electrons in an atom's shells.

Conductors

Materials easily conducting electrical current.

Insulators

Materials not conducting electrical current.

Covalent Bonding

Chemical bond sharing electrons between atoms.

Energy Gap

Difference in energy levels between orbital shells.

Conduction Band

Band outside valence shell with free electrons.

Covalent Bonding of Silicon

Silicon atoms sharing valence electrons.

Ionic Bonding

Bond formed by electron transfer between atoms.

Metallic Bonding

Attraction between valence electrons and metal atoms.

Conductivity

Measure of material's ability to conduct electricity.

Resistance

Capacity to impede electric current flow.

Resistivity

Material's resistance level measured in ohm-meters.

N-Type Semiconductor

Semiconductor with added pentavalent impurities.

P-Type Semiconductor

Semiconductor with added trivalent impurities.

PN Junction Theory

Formation of a PN-junction in semiconductor devices.

Depletion Layer

Region around PN junction devoid of free carriers.

Potential Barrier

Built-in potential difference across a junction.

Diode

Device allowing current flow in one direction.

Barrier Potential

Voltage required to move electrons across a field.

Forward Bias

Applying voltage to control diode operation.

Dynamic Resistance

Small voltage drop due to material resistance.

Reverse Bias

Condition preventing current flow through a diode.

Current Flow

Current flow is negligible in most cases.

Depletion Region

Region that widens in reverse bias.

Forward Current (If)

Current when a forward bias voltage is applied.

Diode Structure

A two-terminal device conducting in one direction.

Ideal Diode Model

Model where diode acts as a perfect conductor or insulator.

Practical Diode Model

Model adding barrier potential to ideal switch model.

Complete Diode Model

Model including barrier potential, Rd, and internal resistance.

Anode

Positive terminal of a diode.

Cathode

Negative terminal of a diode.

Semiconductor Materials

Materials like Silicon, Germanium, and Gallium Arsenide used in diodes.

Diode Operating Conditions

Conditions like No Bias, Reverse Bias, Forward Bias, and Zener Region.

Breakdown Voltage

Voltage causing a diode to enter the breakdown region.

Avalanche Effect

Current multiplication at breakdown due to high reverse voltage.

Peak Inverse Voltage

Maximum reverse voltage not entering the Zener region.

Temperature Effects

Effects of temperature on diode characteristics.

DC Resistance

Resistance at a specific applied DC voltage.

AC Resistance

Resistance depending on the current in the diode.

Diode Capacitance

Capacitance in reverse and forward bias.

Reverse Recovery Time (trr)

Time for a diode to stop conducting when switched from forward to reverse bias.

Diode Checker

Device like an Ohmmeter used to test diodes.

Rectification

Process of converting AC to DC using diodes or other devices.

Rectifier

Device converting AC to DC by means of diodes.

Power Supply Unit

Circuit converting AC input to DC output.

Transformer

Device changing voltages based on turns ratio.

Half-Wave Rectifier

Rectifier circuit using only half of the input waveform.

Full-Wave Rectifier

Rectifier using both halves of the input waveform.

Bridge Rectifier

A type of rectifier that converts AC to DC using four diodes in a bridge configuration.

Clipper Circuit

A circuit that removes a portion of an input signal without distorting the remaining waveform.

Clamping Circuit

A circuit that shifts the DC level of a signal either upward or downward without clipping.

Voltage Doubler

A device that delivers double the peak voltage using a capacitor filter circuit.

Zener Diode

A highly doped silicon PN-junction device designed for operation in the reverse-breakdown region to maintain a specific voltage across its terminals.

Optical Diodes

Devices based on PN-junction action in optoelectronics, including LEDs, photodiodes, optocouplers, and laser diodes.

Light Emitting Diode (LED)

Emits photons as visible light for indication and displays, with added impurities to vary color output.

Photodiode

Varies current based on incident light, conducting reverse current proportional to light intensity.

Laser Diode

Produces monochromatic light through stimulated emission of radiation, used for data retrieval from compact discs.

Varactor Diode

Acts as a variable capacitor, used as voltage-controlled capacitors in communication systems.

Schottky Diode

A fast-switching diode with no PN-junction, consisting of heavily doped n-material and metal bound together.

PIN Diode

Consists of heavily doped p and n regions separated by an intrinsic region, used for attenuation, modulation, and switching.

Step-Recovery Diode

A diode with less doping near the junction, known as a voltage-dependent variable capacitor or Snap-off Diode.

Tunnel Diode

A semiconductor diode with negative resistance due to tunneling effect, conducting well with low forward bias.

Current Regulator Diode

Also known as a constant-current diode, maintains a constant current in forward bias.