Semiconductor Diodes, Rectifiers, and Waveshaping Circuits
1. Scientific Formulas in Electronics
Q1. Explain the three kinds of formulas with examples.
- Definition: A formula invented for a new concept. It is accepted as true by agreement. Example: C = Q / V, R = V / I.
- Law: A formula describing a relationship that already exists in nature. It is true because experiments verify it. Example: Coulomb’s Law, F = k · (Q₁Q₂) / d², where k = 9 × 10⁹ N·m²/C².
- Derivation: A formula obtained from other formulas using mathematics. It is true because mathematical
analog electronics
A real P-N junction diode has a highly non-linear current–
voltage (I-V) relationship, which makes circuit analysis mathematically tedious.
Ideal Diode Model
This is the simplest approximation. It treats the diode as a perfect one-way valve. -Forward Bias (ON): Acts as a perfect short circuit (0V drop, infinite current capacity). -Reverse Bias (OFF): Acts as a perfect open circuit (0A current flow).
Constant Voltage Drop Model (The Practical Model):
This is the most widely used model for everyday
Read MoreTransformer Testing Methods and Operational Principles
Transformer Testing: Open Circuit and Short Circuit
The primary goal of the Open Circuit (O.C.) test is to determine the transformer’s core (iron) losses and the shunt branch parameters (magnetizing resistance and reactance).
- Setup: The High Voltage (HV) winding is left completely open (no load). Rated voltage at rated frequency is applied to the Low Voltage (LV) winding.
- It is much safer and more practical to supply the standard rated voltage to the low-voltage side (e.g., 230V) than the high-voltage
Electrical Instrumentation and Measurement Principles
Strain Measurement with Strain Gauges
A strain gauge is a resistive transducer that changes its electrical resistance in proportion to the mechanical strain applied to it.
Principle and Gauge Factor
When a conductor is stretched, its length increases and diameter decreases, both of which increase resistance (R = ρL/A). The Gauge Factor (GF) is defined as: GF = (∆R/R) / (∆L/L) = (∆R/R) / ε, where ε is strain. For metallic gauges, GF ≈ 2; for semiconductor gauges, GF = 100–150.
Wheatstone
Read MoreHidden Surface Elimination and CRT Display Technology
When rendering a 3D scene onto a 2D screen, objects closer to the camera must obscure objects that are behind them. Identifying and removing parts of a scene that are blocked from view is called Hidden Surface Elimination (or Visible Surface Detection).
These techniques are divided into two categories: Object-Space methods (which analyze physical geometry in 3D coordinates) and Image-Space methods (which work pixel-by-pixel in 2D screen coordinates).
1. Back-Face Removal (Object-Space)
Back-face removal
Read MoreElectrical Power Systems: Circuit Breakers and Machines
Transient Phenomena in Power Lines
A1. Transient Switching Phenomena
When an inductive power line is switched on, the steady-state sinusoidal current is not reached immediately. Since current through an inductance cannot change instantaneously, a transient DC component appears if the switching instant does not match the steady-state initial value. The current is defined as i(t) = i_st(t) + i_tr(t). The worst case occurs in highly inductive circuits when energization happens near voltage zero.