Lesson 3: Electronic Components

Diode

A device that allows current to flow in only one direction. The joining of N-type and P-type materials. The positive side is referred to as the anode (A), and the negative side is referred to as the cathode (K).

Light Emitting Diode

A device that will produce light when current flows through it in one direction. Made for the purpose of emitting light. Though they still provide a rectification effect, it has no practical application. The circuit diagram symbol for diodes features a triangle and a line arranged so that the direction of current flow is easily understood. The symbols for these also feature arrows to represent light.

Semiconductor

A material that conducts current or exhibits insulating properties depending on states and conditions. Specific impurities are added when manufacturing them that cause an excess or deficiency in the amount of electrons which alters its electrical properties.

DC Input for a Controller

A port into which the DC power connector is inserted that allows a supply of electrical currents to be exchanged between a device and an electrical source. Often the exchange device is a photocoupler.

Transistor

A small electronic device used in a circuit as an amplifier or switch via current. Can be used for switching operations to turn a significant amount of current on and off with a minimal amount of current, and for amplification operations to convert small changes in current into larger changes in current.

TRIAC

A three terminal device used to control the average current flow to a load. Switches bidirectional current. Represented as a combination of two thyristors to enable switching of bidirectional current flow. The actual structure is different than the shorthand representation of two thyristors.

Phototransistor

A transistor that responds to light striking it by generating and amplifying an electric current. Current flows between C-E when light is received.

FET

A type of transistor structure that control current between a source (S) and drain (D) through voltage applied to a gate (G). The semiconductor layer that forms the current path is divided into N and P channels.

Resistor

An electrical device that prevents the flow of electricity which is converted into heat. Symbol: R

Coil

An electrical device that stores electrical energy. Direct current flows through these components. For alternating current, the impedance increases as the frequency rises which decreases the flow of electricity.

Capacitor

An electrical device used to store electrical energy. Direct current does not flow through capacitors. For alternating current, the impedance increases as the frequency lowers, which decreases the flow of electricity. Symbol: C

MOSFET

Circuit diagram for this device

Rectification

Electricity only flows through in one direction.

Active Components

Electronic components that have rectification and amplification effects.

N-Type Material

Electrons are majority carrier. Holes are minority carrier.

Field Effect Transistor

FET

P-type Material

Holes are a majority carrier. Electrons are a minority carrier.

Transistor Symbol

In a circuit diagram, the emitter arrow represents the flow of electricity.

Junction Field Effect Transistor

JFET

JFET

Junction Fet. Simplest type of FET. Can be used as an electronically controlled switch, amplifier, or voltage-controlled resistor.

Metal Oxide Semiconductor Field Effect Transistor

MOSFET

MOSFET

Metal Oxide Semiconductor Field Effect Transistor. Amplifies or acts as a switch via voltage. Since control current does not flow through them, they do not emit much heat and are more energy saving in comparison with transistors. For this reason they are used for power control.

Cathode

Negative side of the electrode/diode

Anode

Positive side of the electrode/diode

Thyristor

Switches unidirectional current. Current flows from the gate (G) to the cathode (K) in which conduction can occur between the anode (A) and cathode (K). Current cannot flow from the cathode to the anode. Used to quickly turn a significant amount of DC on and off.

Impedance

The opposition to the flow of energy or the reluctance to accept energy.' Calculated from current and voltage. It includes the power factor angle so that direct current resistance values can also be used for alternating current. The unit is the same as for resistance, which is Ω.

Photocoupler

The packaging of a light-emitting unit and a light-receiving unit into one component. Usually implemented with an LED and a phototransistor. The phototransistor turns on allowing current to flow when a certain level of current flows through the LED. Circuits can be electrically isolated using photocouplers as light is used to turn both the LED and phototransistor side of the component on and off. These are used in DC input units of controllers (I/O units).

Transistor Schematic

The thin layer in the middle is the base (B), the layer from which current is output is the emitter (E), and the layers where current is collected is the collector (C).

Passive Components

These do not have rectification or amplification effects such as resistors, capacitors, and coils

PNP

This is one of the two types of bipolar transistors, consisting of a layer of N-doped semiconductor (the "base") between two P-doped layers. A small current entering the emitter is amplified to produce a large emitter to collector current.

NPN

This is one of the two types of bipolar transistors, consisting of a layer of P-doped semiconductor (the "base") between two N-doped layers. A small current entering the base is amplified to produce a large collector to emitter current.

N-Channel MOSFET

This type of MOSFET