# Scope-Trace QuizMarch 1965 Popular Electronics

 March 1965 Popular Electronics   Table of Contents Wax nostalgic about and learn from the history of early electronics. See articles from Popular Electronics, published October 1954 - April 1985. All copyrights are hereby acknowledged.

Just yesterday I posted an article titled "Understanding Your Triggered Sweep Scope," that appeared in the May 1973 issue of Popular Electronics, so I figured this "Scope-Trace Quiz" would make a good compliment. It is from a 1965 issue of Popular Electronics. Driver circuits all include a sinewave source in parallel with a series resistor and diode, connected to the vertical and horizontal o-scope inputs. The resulting Lissajous waveforms resemble hands on a clock face thanks to the diode. Shamefully, I only scored 70%, but in my own defense I'll say I didn't take the time to draw them out on paper. Pay careful attention to the scope connections.

## Scope-Trace Quiz

By Robert P. Balin

How are you at vectors? Here's a chance to get some practice and test your scope sense. The vertical and horizontal input signals to an oscilloscope combine to form Lissajous patterns whose appearance depends on the waveform, frequency, and relative phase of the two signals. Knowing how these patterns are formed will help you to interpret waveforms and to have a better understanding of the scope. Test your ability to project (vectorially) the forces at work on the electron beam in the CRT. Six different oscilloscope traces are shown in A-F. Can you match them with circuits 1-6 below?

The resistor used in each circuit has a value equal to the reverse resistance of the diode. Forward resistance of the diode is negligible. The circuits shown do not load or distort the signal source. Both the vertical and horizontal gain controls have been set to provide equal gain. Positive-going signals cause the beam to be deflected upward for the vertical input and to the right for the horizontal input, The example at left shows the resultant trace derived from the same signal applied to both the vertical and horizontal scope inputs. Tips on how to solve this quiz appear with the answers (at bottom of page).

Popular Electronics published many quizzes over the years - some really simple and others not so simple. Robert Balin created many of the quizzes. This is a listing of all I have posted thus far.

 Electronics IQ Quiz - May 1967 Plug and Jack Quiz - December 1967 Electronic Switching Quiz - October 1967 Electronic Angle Quiz - September 1967 International Electronics Quiz - July 1967 Bridge Circuit Quiz -December 1966 Diode Function Quiz - August 1965 Diagram Quiz, August 1966 TV Trouble Quiz, July 1966 Electronics History Quiz, December 1965 Scope-Trace Quiz, March 1965 Electronic Circuit Analogy Quiz, April 1973 Test Your Knowledge of Semiconductors, August 1972 Ganged Switching Quiz, April 1972 Lamp Brightness Quiz, January 1969 Lissajous Pattern Quiz, September 1963 Electronic Quizoo, October 1962 Electronic Photo Album Quiz, March 1963 Electronic Alphabet Quiz, May 1963 Quiz: Resistive? Inductive? or Capacitive?, October 1960 Vector-Circuit Matching Quiz, June 1970 Inductance Quiz, September 1961 RC Circuit Quiz, June 1963 Diode Quiz, July 1961 Electronic Curves Quiz, February 1963 Electronic Numbers Quiz, December 1962 Energy Conversion Quiz, April 1963 Coil Function Quiz, June 1962 Semiconductor Quiz - February 1967 Unknown Frequency Quiz - September 1965 Electronics Metals Quiz - October 1964 Electronics Measurement Quiz - August 1967 Meter-Reading Quiz, June 1966 Electronic Geometry Quiz, January 1965 Electronic Factor Quiz, November 1966 Electronics Math Quiz, November 1965 Series Circuit Quiz, May 1966 Electrochemistry Quiz, March 1966 Electronic Analogy Quiz, November 1961 Electronic Coupling Quiz, August 1973 Electronics Analogy Quiz, August 1960 Audio Quiz, April 1955 Electronic Unit Quiz, May 1962 Capacitor Circuit Quiz, June 1968 Quiz on AC Circuit Theory, December 1970 Magnetic Phenomena Quiz, February 1962 Electronics Geography Quiz, April 1970 Electronic Menu Quiz, August 1963 Electronic Noise Quiz, August 1962 Electronic Current Quiz, October 1963 Electronic Inventors Quiz, November 1963 Resistor Function Quiz, January 1962 Electronic Measurement Quiz, January 1963 Vacuum Tube Quiz, February 1961 Kool-Keeping Kwiz, June 1970

If you had trouble solving this quiz, consider the following facts:

(1) Output across the complete resistor and diode circuit is the same amplitude as the input signal.

(2) Output across the resistor only varies between 50% and 100% (100% when the diode is working in the forward direction).

(3) Output across the diode varies between 50% and 0% (0% when the diode is working in the forward direction).

Posted February 27, 2018

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