1

Simulating Circuits Using QUCS, the Quite Universal Circuit Simulator

Doug Reece, AK4AOMay 22, 2015

2

About QUCS

• Free software!• Provides CAD tools for drawing schematic

diagrams• Simulates the behavior of the circuit represented

by the schematic– DC– AC

• Frequency domain• Time domain

– Digital logic

3

Uses for QUCS

• Students/hobbyists: Experiment with various types of electronic circuits without components and lab instruments

• Professionals: Analyze circuit performance before building

Caution: Models don’t capture all aspects of a real circuit: stray capacitance/inductance, hum pickup, etc.

4

DC Circuit: Voltage Divider

5

Voltage Divider with Parameter Sweep

6

AC Circuit – Frequency Domain

AC Circuit – Time Domain

7

8

Digital Logic Simulation

9

Some other QUCS Features

• Libraries of real devices• Filter design • Attenuator design• Equations, including differential equations• Optimization

10

Resources

• URL for software (MAC, Windows, various Linux flavors, source code) http://qucs.sourceforge.net/

Note: Windows version loads several programs• Tutorials:

http://qucs.sourceforge.net/docs.html