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# Lissajous Pattern QuizSeptember 1963 Popular Electronics

 September 1963 Popular Electronics   [Table of Contents People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Popular Electronics was published from October 1954 through April 1985. All copyrights are hereby acknowledged. See all articles from Popular Electronics.

Jules Antoine Lissajous was a French mathematician who in the days before oscilloscopes concerned himself with patterns (waveforms) that would be generated as the result of two separate functions (signals) driving both the x- and y-axes. Lissajous used mechanical vibration devices connected to mirrors to bounce light beams onto a projection surface, so his results were not merely hand-drawn plots on graph paper. He was probably as mesmerized with them as we are today when they appear. Sci-fi movies have used Lissajous patterns in the background to 'wow' the audience into thinking it is witnessing futuristic, cutting-edge technology. When troubleshooting analog circuits, it is very advantageous to have seen and recognize many different types of waveforms so that you have a better chance of picking out patterns when you see them again. Finding sources of interference and power supply modulation are good examples. This quiz will helps you get started or test your already finely honed knowledge of Lissajous patterns.

Lissajous Pattern Quiz

By Robert P. Balin

A good technician, knowing what sine-wave signals are simultaneously applied to the horizontal and vertical inputs of an oscilloscope, can predict what the displayed Lissajous pattern will be. In this quiz, the same signal is applied to both amplifiers, but through combinations of impedances that cause differences in the phase angle and amplitude of the actual a.c. voltages reaching the inputs. All resistances and reactances have the same ohmic impedance at the applied frequency, the gain of both amplifiers is equal, and positive-going voltage deflects the spot upward, or to the right. See if you can match up the input circuits (1 - 6) with the patterns (A - F) produced.

Quizzes from vintage electronics magazines such as Popular Electronics, Electronics-World, QST, and Radio News were published over the years - some really simple and others not so simple. Robert P. Balin created most of the quizzes for Popular Electronics. This is a listing of all I have posted thus far.

1 - E

V = .707E; H = E

2 - D

V = E

H = O

3 - A

V = O

H = E

4 - F

V = H = E/2

V is 180° out-of-phase with H

5 - B

V = .707E

H = .707E

V leads H by 90°, but signals are taken off 180° out-of-phase; hence V lags H by 90°

6 - C

V = E

H = E

V and H in phase

Posted August 28, 2019
(updated from original post on 2/1/2015)