Essential Electronic Components and Circuit Prototyping Techniques

Essential Passive and Active Electronic Components

Resistors: Current Control and Sensing

Fixed resistors act as current limiters and are used to protect other components that cannot handle very high current. Resistor applications include:

• Fixed Resistors: Used for current limiting and voltage division.
• Potentiometers (Variable Resistors): Can vary resistance, making them useful as voltage regulators and power controls.
• Dependent Resistors (Sensors): Allow use as sensors in automatic systems (e.g., LDRs, Thermistors).

Capacitors: Charge Storage and Filtering

Capacitors are passive components designed to store electric charge. The main characteristic of a capacitor is its capacitance (C), representing the amount of electric charge (Q) it is capable of storing in proportion to the voltage (V) applied.

The relationship is defined by the formula: $Q = CV$. The text mentions time constants related to charging and discharging: Charge time = 3RcC and Discharge time = 3RdC.

Capacitor applications include:

• Acting as accumulators (temporary energy storage).
• Timing and load circuits.
• Serving as filters in power supplies and signal processing.

Diodes: Unidirectional Current Flow

Diodes are active components that allow electric current flow in one direction and block it in the opposite direction. Diodes only allow electric current conduction when the anode is connected to a higher potential than the cathode, and the potential difference exceeds a specified forward voltage value.

Diode applications include:

• Switching or automatic connection and disconnection.
• Rectification: Allowing passage for positive voltage and blocking the passage to negative voltages.

Prototyping and Circuit Fabrication Techniques

Solderless Breadboards (Protoboards)

Solderless breadboards are useful for test assemblies that are later disassembled for component reuse. The board forms a connection matrix to insert components and connect them using jumper cables.

Perforated Boards for Experimental Setups

Perforated boards are used in experimental setups, consisting of a drilled grid with tin-plated contacts to which components are soldered together, often using flexible cables.

PCB Manufacturing: Creating Permanent Circuits

Blank PCB (Printed Circuit Board) blanks are used for final circuits. They have a thin layer of copper on one or both surfaces on which connections between components are formed. These boards must be drilled to insert and solder the components.

PCB Manufacturing Steps:

1. Track Transfer: Tracks are transferred onto the virgin copper plate, typically done by screen printing or photo printing.
2. Etching: The plate is immersed in an acid bath for the removal of excess copper.
3. Component Placement: Components are placed on the surface or inserted into previously drilled holes.
4. Soldering: Welding is done at the terminals by immersion in liquid tin or manually using a pencil-type soldering iron and solder wire.