Electronic Door Entry & Access Control Systems
Electronic Door Entry Systems
Porter-mail is a communication and safety device used to control access to residential and commercial buildings.
Components of an Electronic Door Entry System
Power Supply
Adapts the required voltage (12V or 15V DC) for system components. The power supply’s capacity depends on the number of openers and telephones connected.
Entrance Panel
Houses the buttons, speaker, and microphone for communication. Compact and modular designs accommodate various user numbers. Recessed
Read MoreUnderstanding Gears and Mechanisms: Types, Functions, and Applications
Understanding Gears and Mechanisms
Gears: Transmitting Rotational Force
A gear is a component within a transmission device that transmits rotational force to another gear or device. Unlike a pulley, a gear is a round wheel with teeth or cogs that mesh with other gear teeth, ensuring efficient force transfer without slippage.
Geared devices can transmit forces at different speeds, torques, or directions, depending on their construction and arrangement. Gears are versatile simple machines that can mesh
Read MoreInternal Combustion Engine Deep Dive
Internal Combustion Engine
1. History of the Engine
The internal combustion engine evolved from the steam engine. The key difference is that the internal combustion engine generates work from a mixture of air and fuel, while the steam engine uses steam pressure from external combustion.
Key milestones:
- May 1876: Nikolaus Otto builds the first four-stroke engine.
- 1878: Dugald Clerk builds the first two-stroke engine.
- 1882: Gottlieb Daimler and Wilhelm Maybach start their company, focusing on lightweight,
Understanding Distributed Systems: Architecture, Features, and Design
Distributed Systems
A distributed system comprises hardware and software elements that communicate via messages, locally or remotely.
Distributed Applications
A distributed application is a software component available on different computers or architectures, providing user interfaces for system interaction.
Key Features of Distributed Systems
Seven essential features characterize distributed systems:
- Heterogeneity: Diversity in hardware, software, and communication components.
- Extensibility: Ability to
Understanding Simple Machines, Mechanisms, and Mechanical Elements
Mesopotamia and the Dawn of Simple Machines
Around 3500 BC, Mesopotamian philosophers identified five simple machines: the wedge, inclined plane, wheel, and lever. All early machines were based on these or their combinations. The fundamental principle: the driving force equals the resisting force.
When a force acts on an object, it tends to deform it. This deformation depends on the force’s direction, orientation, and application point. Machine elements experience various efforts:
- Traction (lengthening)
Semiconductors, Variable Resistance, and PN Junctions
Variable Resistance
Photoresistors (LDR) are photoresistive cells whose electrical resistance depends on the light they receive.
Thermistors (RTD) consist of a metal wire whose resistance varies with temperature. Rt = Ro (1 + αT).
Thermistors are resistors that vary with temperature but do not consist of metallic conductors; instead, they are semiconductors.
Varistors are components whose resistance varies according to the applied voltage (VDR). The relationship between voltage and current is not linear:
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