January 1945 RadioCraft
[Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from RadioCraft,
published 1929  1953. All copyrights are hereby acknowledged.

This Electronic Puzzle Square,
compliments of Lt. C.K. Johnson, appeared in the January 1945 issue of RadioCraft
magazine. It consists of electronicsrelated numerical questions whose answers,
if correct, create a 4x4 matrix whose columns, rows, and long diagonals all
add up to 45. Noninteger answers need to be rounded according to standard rules
(do not just truncate). In case you left your slide rule at the office, a link
is provided to assist with Q2. The biggest head scratcher question is Q4, since
it requires the conversion from polar to rectangular coordinates, but hey, you're
an engineer (or a crack technician). Having Euclid onhand for Q5 might be helpful.
A link is provided to a copper wire parameter table for Q9. Have fun.
Here is another
Electronic Puzzle
Square from the July 1945 issue.
Electronic Puzzle Square
By Lt. C. K. Johnson
Here is a new idea in a Magic Square. Work problem No. 1 and put the answer
in square No. 1. The answer to problem 2 goes in square 2, etc. When all 16
problems are completed, the rows, columns diagonals and various other combinations
will total a number which is the type number of a popular power amplifier triode
frequently used pushpull to give a power output of about 18 watts with 275
volts on the plate.
The numbers add up to 45 in every direction,
if answers are correct.
1. The total resistance between A and B is ____ ohms.
2. On a
slide rule, 64 on the right hand side of the A scale is directly over ____
on the D scale.
3. The pentode is a ____ element tube.
4. 21.18/8.1° would equal ____ +3j in rectangular coordinates.
5. If a regular hexagon is inscribed in a circle whose radius is one inch,
the perimeter of the hexagon is ____ inches.
6. What is the voltage between A and B?
7. Two 12 volt batteries hooked in parallel will give ____ volts.
8. 0.142857 is the reciprocal of _____.
9. B&S gage bare copper wire No. ____ has a circular mil area of 1,288
and at 25 °C. has a resistance of 8.1 ohms per 1,000 feet. (see table
here)
10. To find wavelength in meters when frequency in kilocycles is known, we
have a formula λ = (c x 10^{5})/f
. What digit does "c" replace?
11. In the R.M.A. color code, silver represents a tolerance of what percent?
12. What is the total capacitance in mfd. between A and B?
13. Effective voltage (in alternating current of sinewave form) is to average
voltage as 10 is to ____ .
14. What will be the voltage across the 1megohm resistor exactly 1.967 seconds
after the switch (S_{1}) is closed, allowing current to enter the resistorcondenser
combination?
15. In this circuit the problem is to find the current in milliamperes if
1.62 watts is dissipated in the 500ohm resistor.
16. Yellow is ____ in the color code.
Answers
Posted February 25, 2021
