Understanding Mechanical and Electrical Systems: Levers, Transmissions, and Electronics
Types of Levers
First Class Lever: Fulcrum between the load and the effort (R, PA, F).
Second Class Lever: Load between the fulcrum and the effort (PA, R, F).
Third Class Lever: Effort between the fulcrum and the load (PA, F, R).
Mechanical Transmissions
Screw Gear
Used to transmit movement, typically at a 90° angle. It has a single tooth-shaped screw engaging with a toothed wheel. Each rotation of the screw advances the wheel by one tooth. Characteristics include transmitting motion through right angles, high cost, and quiet operation.
Rack and Pinion System
Consists of a pinion (a small gear with straight teeth) meshing with a rack (a linear gear). Rotating the pinion causes the rack to move linearly. This mechanism transforms rotational motion into linear motion, and vice versa.
Screw and Nut System
A screw with a nut that fits its thread. Rotating the screw while holding the nut fixed causes the nut to move linearly along the screw’s axis. Conversely, fixing the screw’s orientation and rotating the nut causes the screw to advance linearly.
Crank and Rod System
Consists of a crank and a connecting rod. Rotating the crank transmits circular motion to the rod, which experiences reciprocating (back-and-forth) motion. This system also works in reverse.
Crankshaft
If a series of angled rods are placed on the same shaft, each acting as a crank, the assembly is called a crankshaft. It transforms rotational motion into multiple, alternating, out-of-phase reciprocating motions of the rods. It can also convert reciprocating motion of the rods into rotational motion of the shaft.
Cam Mechanism
A rotating element with a salient lobe that pushes a follower. The cam transforms the wheel’s rotational motion into alternating linear motion of the follower, which traces the cam’s profile as it rotates.
Eccentric Mechanism
Consists of a rotating wheel whose axis of rotation does not coincide with its geometric center. This transforms the wheel’s rotational motion into alternating linear motion of a rod. The eccentricity is the distance between the center of the wheel and the axis of rotation.
Electrical Magnitudes
Electric Charge: Measured in Coulombs (C).
Current Intensity: Measured in Amperes (A, using an ammeter). 1 A = 1 C/s
Resistance: Measured in Ohms (Ω, using an ohmmeter).
Voltage: Measured in Volts (V).
Ohm’s Law: I = V / R, V = I * R, R = V / I
Electrical Power: P = V * I = I2 * R
Electrical Energy: E = V * I * t
Types of Current
Direct Current (DC): Low voltage, low intensity, thin cables. Electrons flow in one direction, and the intensity is constant over time.
Alternating Current (AC): High voltage, current flows in both directions, and the intensity changes continuously.
Electronic Components
Resistors
Tolerance: The difference between the actual and nominal resistance value. It represents the range of possible values for a resistor.
Potentiometers: Variable resistors whose resistance can be adjusted using a cursor. Used for volume control, brightness adjustment, etc.
Light Dependent Resistor (LDR): Resistance varies with the amount of light received (more light, less resistance).
Thermistors: NTC (Negative Temperature Coefficient: +Temperature, -Resistance), PTC (Positive Temperature Coefficient: +Temperature, +Resistance).
Diodes
An electronic component made of semiconductor material that allows current to flow in one direction only. A Light Emitting Diode (LED) emits light when current passes through it.
Transistors
A fundamental element in electronic circuits, consisting of a collector, base, and emitter. It is made of three layers of semiconductor material with three terminals, encapsulated for mounting on a circuit.
Capacitors
Composed of two flat, parallel metal plates separated by an insulator. It can store electrical energy.
Databases
A collection of data organized and stored according to a specific criterion.
Record (Row)
Contains all the information on various topics.
Field (Column)
Represents the different categories into which the contents of a record are divided.
Form
Presents the same data as a table but in a more organized, attractive, and user-friendly format. Allows for data entry and modification.
Query
A powerful process for interrogating the database to retrieve organized and usable data.
Report
A summary containing data from one or more tables, formatted for presentation on paper in an organized manner.