November 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.
1965 was near the beginning
of the transition from vacuum tubes (plasma state) to semiconductors (solid state). If
you are not familiar with tube circuits, when deciding what type of mathematical operation
is being performed by each circuit, mentally replace the tube with a FET or a BJT. The
tube plate becomes the transistor drain or collector, the cathode is the source or emitter,
and the control grid is the gate or base, respectively. Don't worry about biasing. Circuits
A, D, and I should prove to be the easiest. Circuit F is pretty obvious if you look at
the input and output waveforms shown. Anyone familiar with analog power supplies will
breeze through circuits B and G (hint: count the number of charge storage components).
For the others, ignore that there is a squarewave shown at the input since the function
is not dependent on a squarewave to work. For circuit H, mentally reposition the bottom
tube above the other and have the B+ line point upward, then figure out what happens
as each turns on. It was common to draw B+ lines pointing downward whereas in transistor
circuits they normally point upward or sideward. Think of the two tubes in circuit E
as parallel resistors changing value (point B+ upward). Circuit C takes a bit of work
(hint: the circuit is a detector). Circuit J is the toughest of all, but if you get the
other 9 correct, only one possible answer remains from which to choose - that's how I
Electronics Math Quiz
By Robert P. Balin
Many basic electronic circuits can and do perform mathematical operations ranging
from elementary arithmetic to integral calculus. See if you can identify the electronic
circuits (A-J) below which perform the mathematical operations (1-10) at right.
1) Add ____________
2) Count ____________
3) Differentiate ____________
4) Double ____________
5) Divide ____________
6) Integrate ____________
7) Ratio ____________
8) Square ____________
9) Subtract ____________
10) Triple ____________
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.
- Diagram Quiz, August
- TV Trouble Quiz,
- Electronics History Quiz,
- Scope-Trace Quiz,
March 1965 Popular Electronics
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
Factor Quiz, November 1966
Math Quiz, November 1965
- Series Circuit Quiz,
Electrochemistry 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
Math Quiz Answers
1 - H Amplifiers which have their load resistors in series produce an
output signal proportional to the sum of the in-phase input signals.
2 - F A step counter produces an escalated output which varies exponentially
with the number of pulses it receives. It can be used to count the number of pulses it
receives, and as a frequency divider by allowing it to trigger another circuit, say at
every 2nd, 3rd ... 7th step, as desired.
3 - I A differentiator circuit produces an output whose instantaneous
values are proportional to the rate of change of the input voltage waveform.
4 - G A voltage doubler produces a d.c. output which is approximately
equal to twice the r.m.s. value of the a.c. input voltage.
5 - D A voltage divider provides an output which is in the same proportion
to the applied voltage as the divider resistance is to the total resistance.
6 - A An integrating circuit provides an output voltage which is approximately
proportional to the time integral and potential of the input voltage.
7 - J In a ratio detector circuit, the variations of audio frequency output
signals have the same ratio as the variations of the applied FM radio frequency signals.
8 - C A triode square law detector produces an output signal which is
proportional to the square of the input signal.
9 - E A differential amplifier produces an output signal whose amplitude
is proportional to the difference between two in-phase input signals.
10 - B A voltage tripler circuit produces a d.c. output which is approximately
equal to three times the r.m.s. value of the a.c. input voltage.
Posted April 25, 2018