March 1965 Popular Electronics
Table of Contents
Wax nostalgic about and learn from the history of early electronics. See articles
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.
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).
See answers below.
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.
- A Baffling Quiz
- January 1968
- Electronics IQ Quiz
- May 1967
- Plug and Jack Quiz
- December 1967
Switching Quiz - October 1967
Angle Quiz - September 1967
Electronics Quiz - July 1967
- Bridge Circuit
Quiz -December 1966
- Diode Function
Quiz - August 1965
- Diagram Quiz, August
- TV Trouble Quiz,
- Electronics History Quiz,
- Scope-Trace Quiz,
Circuit Analogy Quiz, April 1973
Your Knowledge of Semiconductors, August 1972
- Ganged Switching
Quiz, April 1972
- Lamp Brightness
Quiz, January 1969
- Lissajous Pattern Quiz, September 1963
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
Quiz, September 1961
- RC Circuit
Quiz, June 1963
- Diode Quiz,
- Electronic Curves Quiz, February 1963
- Electronic Numbers Quiz, December 1962
- Energy Conversion Quiz, April 1963
Function Quiz, June 1962
Quiz - February 1967
- Unknown Frequency
Quiz - September 1965
Metals Quiz - October 1964
Measurement Quiz - August 1967
- Meter-Reading Quiz,
Geometry Quiz, January 1965
Factor Quiz, November 1966
Math Quiz, November 1965
- Series Circuit Quiz,
Quiz, March 1966
- Electronic Analogy
Quiz, November 1961
Coupling Quiz, August 1973
- Electronics Analogy Quiz, August 1960
- Audio Quiz,
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
Function Quiz, January 1962
- Electronic Measurement Quiz, January 1963
Tube Quiz, February 1961
- Kool-Keeping Kwiz, June
- Find the
Brightest Bulb Quiz, April 1960
Scope-Trace Quiz Answers
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