November 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.

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
scored 10:10.
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 (AJ) below which perform the mathematical operations (110) 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
1966
 TV Trouble Quiz,
July 1966
 Electronics History Quiz,
December 1965
 ScopeTrace Quiz,
March 1965 Popular Electronics
 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
 VectorCircuit 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

 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
 KoolKeeping Kwiz, June
1970

Math Quiz Answers
1  H Amplifiers which have their load resistors in series produce an
output signal proportional to the sum of the inphase 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 inphase 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
