Notes, summaries, assignments, exams, and problems for Technology

Programmable Logic Controllers (PLCs) Explained

A Programmable Logic Controller (PLC) is an electronic device capable of processing analog, digital, numeric, and alphanumeric information. It is designed to monitor real-time automated industrial processes. Basically, a PLC consists of a control unit, memory, and input/output modules. PLC manufacturers establish communication with external circuits. These circuits are constituted by sensors that send information from the industrial process to the PLC, and actuators that implement program orders.

Automation Approaches: Wired vs. Programmed

Wired Automation Limitations

Traditional wired automation presents several challenges:

• Requires large conduits and control panels.
• Lacks flexibility; variations do

BT06 Bare Conductors Specifications

Breaking Load:

410 daN

Braces and Struts:

1400 daN

Ultimate Safety Factor

• Metallic: 1.5
• Reinforced Concrete: 2.5
• Wood: 3.5
• Non-metallic: 2.5

1. Isolated Conductors

• Cables Perched

  • Distance from floor: 2.5m
  • Windows: 0.3m top, 0.5m bottom and sides
  • Balconies: 0.3m top and bottom, 1m sides

• Tension Cables

  • Ground distance: 4m
  • Mechanical strength: 800 daN

2. Bare Conductors

• Distance from ground: 4m

• On the Roof

  • Flat parallel: 1.8m if connected to ground, 1.50m otherwise
  • With inclination of 45 degrees: can be reduced to 1m

• Terraces and Balconies

  • Flat parallel: 3m

• Facades

  Protection zone limited to:

  • Plane parallel to the wall at 1m from windows or balconies, further limited by:
    • Plane parallel horizontal top: 0.30m
    • 2 vertical planes, one on each

Understanding Materials: Plastics and Building Essentials

Plastics: Properties, Types, and Applications

Plastics are versatile, man-made materials, predominantly derived from oil. The fundamental process of creating a polymer is known as polymerization. Plastics are broadly categorized into two main types:

• Thermoplastics
• Thermosetting Plastics

Thermoplastics Explained

Thermoplastics can be repeatedly heated, molded, and reshaped. A unique characteristic of thermoplastics is their plastic memory, meaning each time they are heated, they tend to return to their original shape.

Thermosetting Plastics Explained

Thermosetting plastics are generally strong and highly resistant to heat. They undergo a permanent chemical change upon initial heating to a sufficiently... Continue reading "Plastics & Building Materials: Types, Uses, and Characteristics" »

Properties of Metals

• Electrical Conductivity
• Heat Conductivity
• Effort Resistance
• Toughness
• Ductility
• Malleability
• Solid at ambient temperature (except for mercury)
• Economical
• Heavy
• Some are magnetic
• High melting temperature

Types of Non-Ferrous Metals and Alloys

• Copper: Red, excellent thermal and electrical conductor, corrosion-resistant, easily welded, ductile, and malleable.
• Tin: Bluish-white, brilliant, soft steel.
• Zinc: White, very resistant to corrosion and oxidation.
• Aluminum: Brilliant white, light, non-toxic, corrosion-resistant, and less soft.
• Magnesium: Lightest, elevated cost, in liquid state it reacts violently with oxygen.
• Titanium: Very expensive, durable against corrosion, good mechanical resistance, and biocompatible.

Metalworking Processes

• Embossing:

What is JDBC?

JDBC (Java Database Connectivity) is a set of classes and interfaces written in Java that provide a complete API for programming databases from different vendors (e.g., Microsoft SQL Server, Oracle, MySQL, Interbase, Microsoft Access, IBM DB2, PostgreSQL) using SQL (Structured Query Language).

JDBC performs several key functions:

• Connects to the database (hereafter DB), which can be local (on your PC) or remote (on another PC).
• Sends SQL statements to the database.
• Manipulates the records within the database.
• Reflects the outcome of the execution of SQL statements.

JDBC vs. ODBC: Key Differences

JDBC differs from ODBC (Open Database Connectivity), Microsoft's widely used API for accessing various database providers from multiple platforms.... Continue reading "Java Database Connectivity (JDBC) Fundamentals" »

Internet Connection Types

• Phone line
• Cable
• ADSL
• Satellite
• Mobile telephony

Wi-Fi

A Wi-Fi is a type of Internet connection that allows multiple computers to connect to the Internet without wires.

Killer Apps

In computer jargon, killer apps (killer applications) are software that exploit a technology, developing its potential and increasing the sales of hardware that supports it. Examples include PC, Macintosh, and the Boy.

Google

Google is probably the best-known and largest search engine in the world. It also has many useful programs, web applications, and tools.

Wikipedia

Wikipedia is a multilingual, free-content encyclopedia written by thousands of volunteers worldwide and sponsored by a nonprofit foundation. It includes a topical encyclopedia, almanac,... Continue reading "Internet, Software, and Communication Technologies" »

Engine Cooling Systems: An Overview

The primary function of an engine cooling system is to maintain the engine within optimal temperature limits, preventing damage to components while maximizing combustion efficiency. Maintaining the correct operating temperature allows the engine to deliver peak performance. The system should enable the engine to reach its ideal temperature quickly and maintain it regardless of the ambient temperature. Insufficient temperature leads to poor fuel gasification and inadequate lubrication due to increased oil viscosity. Excessive temperature can stress cylinders, increase the risk of pre-ignition, and cause oil thinning and rapid degradation, potentially leading to deformation or galling.

Air Cooling

Air cooling... Continue reading "Engine Cooling Systems: Air vs. Water - Pros & Cons" »

Internet Logistics: Enhancing Efficiency

Logistics aims to satisfy demand under the best conditions of service, cost, and quality, managing the necessary resources to achieve these goals at the lowest possible cost. This highlights the advantage of using the Internet in logistics operations.

Understanding the Internet

The Internet is defined as a global computer network, connecting computers worldwide to exchange information. The main difference compared to other computer networks is that the Internet does not belong to any single country, government agency, or specific company. It is essentially a free network accessible from anywhere on the planet, with no restrictions on the information flowing through it. Several non-profit, hierarchical international... Continue reading "Internet Logistics: Boosting Business Efficiency and Reach" »

The Versatile 555 Timer IC

The 555 timer is a highly versatile integrated circuit that can be configured in various ways using external components, primarily as a monostable (one-shot) or astable (free-running) multivibrator.

555 Monostable Configuration

In a monostable configuration, the circuit's output is initially low (zero). The internal discharge transistor is saturated, preventing capacitor C1 from charging. However, when a negative pulse is applied to the trigger terminal (pin 2), it causes the internal RS flip-flop to change its output state, turning off the discharge transistor. This allows capacitor C1 to charge through the external resistance R1.

When the voltage across the capacitor exceeds 2/3 of the supply voltage, the flip-flop... Continue reading "Mastering 555 Timers, CD4510 Counters, and Digital Logic" »

What is ESD?

ESD (Electrostatic Discharge) is the accumulation of electric charge on a surface. For a person to feel an ESD, it's necessary to accumulate 3000V of static electricity.

How to Prevent ESD

• Save all components in static-safe bags.
• Use grounded pads.
• Use grounded floor mats.
• Use an antistatic wrist strap when working with computers.

Types of Power Changes

• Total Blackout: Complete power outage.
• Partial Blackout: A reduction in voltage.
• Noise: Interference on the power line.
• Peak Voltage: A sudden, sharp increase in voltage.
• Overvoltage: A prolonged increase in voltage.

Material Safety Data Sheet (MSDS)

An MSDS is a document that provides information about material identification, hazardous components that can affect people's health, fire hazards,... Continue reading "ESD, Material Safety, Memory Types, and Workday Structure" »