July 1945 Radio-Craft
[Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
Due to the era in which this
"Electronic Puzzle Square" appeared (1945), I made a couple edits to help prevent
misinterpretation. For instance the "mfd." in question 5 is microfarad (μF) in
today's units standard. Question 4 originally had an upper case "E," which was a
typo since it should have been a lower case "e," as in the base of the natural
logarithm. When working Q7, leave the input and output terminals open when
calculating the equivalent resistance; it's not like doing a "Pi" to "Tee"
attenuator conversion. Q11 originally had "logE" where it should have
been just "e." Q9 is a piece of cake. Question 15 assumes you know the
resistance per foot of #25 B&S (AWG) copper wire, which you can find
here (hint: it's 32.4 Ω/1000 ft). Bon
Here is another
Puzzle Square from the Janaury 1945 issue.
Electronic Puzzle Square
By Lt. C. K. Johnson
Work this like a crossword puzzle. The answer to problem No. 1 goes in square
No.1, etc. When completed, rows, columns and diagonals, etc., will total the
number which is the base of common logarithms. Therefore the sum of the answers
to problems 1, 2 and 3 subtracted from the total gives the answer to problem
(All problems correct to one decimal place.)
1. LogeN = ___ Log10N
2. What is R if I = 10 A and P = 320 W?
3. Red is ___ in the color code.
4. ex = ___ when x = 0.92
5. An inductance of 0.004 henrys is used with a condenser of what value
in mfd. (μF) to obtain a resonant frequency of 1500 cps ?
6. Tangent 59.6° = ___.
7. If we had a circuit as in Fig. 1
where each resistor was 10 ohms, and we wanted to convert it to a circuit as at Fig. 2 so that
the resistance measured between A and B or measured between C and D, would be
the same for each circuit, what resistors would we use in Fig. 2?
8. What reading in milliamperes will be
indicated by the meter?
9. The ratio of the circumference of a circle to
its diameter is ___.
10. What is the total resistance between
A and B?
11. If e-x = 0.0743, what is x ?
12. What would be the required voltage of
battery to read 1.9 volts across R1, R2, and R3?
14. Base of the natural system of logarithms.
15. At 77 °F, what would be the resistance of 64 feet of B and S gauge
No. 25 bare copper wire?
16. If an A.C. generator has an R.M.S. output of 2.4 volts, what is
its peak output?
Posted February 10, 2021