April 1960 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.
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Here is a nifty little exercise
that appeared in the April 1960 edition of Popular Electronics. It has
10 different light bulb circuits and challenges you to figure out which bulb would
burn the brightest. All are intuitively obvious to most of us who have been in the
field for decades, but do you remember how to do a circuit mesh analysis to prove
your "gut?" One way to help figure out what is going on is to re-draw the circuit
to eliminate crossing lines, if possible, as in circuit numbers 2, 4, 6, and 10.
Also try drawing electrically common nodes as a single connection point, as in circuit
#2 where the two nodes in the upper left and right corners are actually the same
point. Finally, try to re-arrange the circuit branches into obvious parallel and
series paths to make clear any interdependencies and independencies.
See answers at bottom of page.
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.
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-
Elementary
Radio Quiz - December 1947 Radio-Craft
- Hi-Fi
Quiz - October 1955 Radio & Television News
- Electronics Physics
Quiz - March 1974 Popular Electronics
- A Baffling Quiz
- January 1968 Popular Electronics
- Electronics IQ
Quiz - May 1967 Popular Electronics
- Plug and Jack
Quiz - December 1967 Popular Electronics
- Electronic
Switching Quiz - October 1967 Popular Electronics
- Electronic
Angle Quiz - September 1967 Popular Electronics
- International
Electronics Quiz - July 1967 Popular Electronics
- FM Radio
Quiz - April 1950 Radio & Television News
- Bridge Circuit
Quiz -December 1966 Popular Electronics
- Diode Function
Quiz - August 1965 Popular Electronics
- Diagram Quiz,
August 1966 Popular Electronics
- Quist Quiz - November
1953 QST
- TV Trouble Quiz,
July 1966 Popular Electronics
- Electronics History Quiz,
December 1965 Popular Electronics
- Scope-Trace Quiz,
March 1965 Popular Electronics
-
Electronic
Circuit Analogy Quiz, April 1973
-
Test Your Knowledge of Semiconductors, August 1972 Popular Electronics
- Ganged Switching
Quiz, April 1972 Popular Electronics
- Lamp Brightness
Quiz, January 1969 Popular Electronics
- Lissajous Pattern Quiz, September 1963 Popular Electronics
- Electronic
Quizoo, October 1962 Popular Electronics
- Electronic Photo Album Quiz, March 1963 Popular Electronics
- Electronic Alphabet Quiz, May 1963 Popular Electronics
- Quiz: Resistive?
Inductive? or Capacitive?, October 1960 Popular Electronics
- Vector-Circuit Matching Quiz, June 1970 Popular Electronics
- Inductance
Quiz, September 1961 Popular Electronics
- RC Circuit Quiz,
June 1963 Popular Electronics
- Diode Quiz, July
1961 Popular Electronics
- Electronic Curves Quiz, February 1963 Popular Electronics
- Electronic Numbers Quiz, December 1962 Popular Electronics
- Energy Conversion Quiz, April 1963 Popular Electronics
- Coil Function
Quiz, June 1962 Popular Electronics
-
Co-Inventors Quiz - January 1965 Electronics World
-
"-Tron" Teasers Quiz - October 1963 Electronics World
- Polarity Quiz
- March 1968 Popular Electronics
-
Television
I.Q. Quiz - October 1948 Radio & Television News
- Amplifier Quiz
Part I - February 1964 Popular Electronics
- Semiconductor
Quiz - February 1967 Popular Electronics
- Unknown
Frequency Quiz - September 1965 Popular Electronics
- Electronics
Metals Quiz - October 1964 Popular Electronics
- Electronics
Measurement Quiz - August 1967 Popular Electronics
- Meter-Reading
Quiz, June 1966 Popular Electronics
- Electronic
Geometry Quiz, January 1965 Popular Electronics
- Electronic
Factor Quiz, November 1966 Popular Electronics
- Electronics
Math Quiz, November 1965 Popular Electronics
- Series Circuit
Quiz, May 1966 Popular Electronics
- Electrochemistry
Quiz, March 1966 Popular Electronics
- Biz
Quiz: Test Your Sales Ability - April 1947 Radio News
- Electronic
Analogy Quiz, November 1961 Popular Electronics
- Electronic
Coupling Quiz, August 1973 Popular Electronics
- Electronics Analogy Quiz, August 1960 Popular Electronics
- Audio Quiz, April
1955 Popular Electronics
- Electronic Unit
Quiz, May 1962 Popular Electronics
- Capacitor
Circuit Quiz, June 1968 Popular Electronics
- Quiz on AC Circuit Theory, December 1970 Popular Electronics
- Magnetic Phenomena Quiz, February 1962 Popular Electronics
- Electronics Geography Quiz, April 1970 Popular Electronics
- Electronic
Menu Quiz, August 1963 Popular Electronics
- Electronic Noise Quiz, August 1962 Popular Electronics
- Electronic Current Quiz, October 1963 Popular Electronics
- Electronic Inventors Quiz, November 1963 Popular Electronics
- Resistor Function
Quiz, January 1962 Popular Electronics
- Electronic Measurement Quiz, January 1963 Popular Electronics
- Vacuum Tube Quiz,
February 1961 Popular Electronics
- Kool-Keeping Kwiz, June
1970 Popular Electronics
- Find the Brightest
Bulb Quiz, April 1960 Popular Electronics
-
Where Do the Scientists Belong? - Feb 19, 1949 Saturday Evening
Post
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ANSWERS: (explanations by Kirt Blattenberger)
When analyzing the circuits, note that for many of the branches one side of the
bulb returns directly to the battery, even though at first look it might appear
to share with another branch. In circuit 3, for example, you can redraw the circuit
connecting the left sides of bulbs A and D directly to the positive battery terminal
(anode). Similarly, the right sides of bulbs B and D and the bottom of bulb C directly
to the negative battery terminal (cathode).
#1: C.
Bulb C is the only one that has the full battery voltage across it. Bulbs A,
B, and D are shorted across their terminals and thus have no voltage across them.
#2: C.
Bulb C is the only one that has the full battery voltage across it. Bulbs A and
B share the battery voltage with bulb D.
#3: D.
Bulb D is the only one that has the full battery voltage across it. Bulbs B and
C share the battery voltage with bulb A.
#4: A.
Bulb A is the only one that has the full battery voltage across it. Bulbs B and
C are shorted across its terminals and therefore have zero volts across them.
#5: B.
This one is a bit tricky, as with circuit #5. Bulbs A and B are in series and
therefore share the battery voltage equally Bulb A is in series with the parallel
combination of bulbs D and E. The intent of the author is likely that you treat
the bulbs as resistors and therefore the parallel combination of bulbs D and E result
in half the total resistance of a single bulb. Therefore, the voltage across those
two bulbs would be Vbatt * (0.5Rbulb / 1.5Rbulb) = 1/3*Rbulb, and the voltage across
bulb B would be 2/3Rbulb. For standard incandescent bulbs, the operational resistance
is dependent on the voltage across the bulb, so the voltage division would not be
as clean-cut as that, but still bulb A would be brighter. If the bulbs were neon
types that maintain a fairly constant voltage across their terminals and regulate
current to maintain the voltage, then provided the battery voltage is high enough,
all three bulbs would burn with equal brightness.
#6: A.
This is essentially the same circuit as #4.
#7: E.
Bulb E is the only one that has the full battery voltage across it. Bulb B's
terminals are shorted and thus 0 volts across it. Bulbs A and C share the battery
voltage with Bulb D.
#8: A.
This one is a bit tricky, as with circuit #5. Bulb B is shorted so it plays no
role. Bulb A is in series with the parallel combination of bulbs C and D. The intent
of the author is likely that you treat the bulbs as resistors and therefore the
parallel combination of bulbs C and D result in half the total resistance of a single
bulb. Therefore, the voltage across those two bulbs would be Vbatt * (0.5Rbulb /
1.5Rbulb) = 1/3*Rbulb, and the voltage across bulb A would be 2/3Rbulb.
#9: C.
Bulb C is the only one that has the full battery voltage across it. Bulbs A and
B are in series with each other and therefore share the battery voltage. The same
goes for bulbs D and E.
#10: E.
A quick mesh analysis, assuming the resistive model for the bulbs, shows that
the current flowing through bulb E is one unit of current while the current flowing
through the other bulbs is 1/2 unit of current. That means bulb E would be the brightest.
Posted August 2, 2019(original 7/4/2012)
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