AC Circuits & Passive/Active Components

AC Circuit Analysis · Passive Components · Active Component Replacement · SPICE Simulation

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Overview

This repository contains LTspice circuit simulation projects from the Electronics Lab course at HAW Hamburg, covering two core topics:

• AC Circuits with Passive Components — analysis of inductors, capacitors, and resistors under AC conditions, including frequency response, Lissajous figures, and bridge circuits
• Active Component Replacement — using active semiconductor devices (Diode, BJT, MOSFET) as functional replacements for passive components

Each .asc file is an LTspice schematic ready to open and simulate.

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Repository Structure

AC_circuits_PassiveComponents/
│
├── AC_Circuits/                          # AC analysis with passive components
│   ├── ACBridgeCircuit.asc               # AC Wheatstone bridge circuit
│   ├── LossResistanceOfInductor.asc      # Inductor loss resistance measurement
│   └── SeriesInductance.asc              # Series inductor frequency response
│
├── Active_Component_Replacement/         # Active devices replacing passive components
│   ├── Diode.asc                         # Diode as passive component replacement
│   ├── BJT.asc                           # BJT as passive component replacement
│   └── MOSFET.asc                        # MOSFET as passive component replacement
│
└── README.md

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Experiments

AC Circuits with Passive Components

File	Description
ACBridgeCircuit.asc	Simulates an AC Wheatstone bridge. Analyzes voltage balance conditions and frequency-dependent impedance matching across resistive and reactive arms.
LossResistanceOfInductor.asc	Models a real-world inductor with series loss resistance. Measures Q-factor degradation and its effect on circuit frequency response.
SeriesInductance.asc	Frequency sweep of a series RL/LC circuit. Observes voltage phase shift, resonance behavior, and Lissajous figure generation.

Concepts: Impedance · Phase shift · Resonance frequency · Lissajous figures · AC frequency response · Q-factor

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Active Component Replacement of Passive Components

File	Description
Diode.asc	Uses a diode to replace a passive component. Characterizes forward voltage, I/V curve, and switching behavior.
BJT.asc	Demonstrates BJT operating as a replacement for a passive component. Analyzes characteristic behavior and operating regions.
MOSFET.asc	Applies MOSFET in a passive component replacement role. Examines gate control, channel resistance, and threshold characteristics.

Concepts: Active vs. passive component behavior · Diode I/V characteristics · BJT operating regions · MOSFET threshold & channel resistance

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Tools

Tool	Purpose
LTspice	Schematic entry & SPICE simulation (.asc files)
Oscilloscope	Waveform measurement and Lissajous figure observation
Function Generator	AC signal source for frequency sweep experiments

Running a Simulation

1. Open any .asc file in LTspice
2. Press Run (F5) to start the SPICE simulation
3. Click on a net or component to probe voltage/current
4. Use the .ac, .tran, or .op directives already set up in each schematic

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Author

Mainuddin Monsur Robin M.Sc. Information and Communication Engineering — HAW Hamburg