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What's Your EQ?
June 1963 Radio-Electronics

June 1963 Radio-Electronics

June 1963 Radio-Electronics Cover - RF Cafe[Table of Contents]

Wax nostalgic about and learn from the history of early electronics. See articles from Radio-Electronics, published 1930-1988. All copyrights hereby acknowledged.

What's Your EQ?, June 1963 Radio-Electronics - RF CafeThree puzzlers for the student, theoretician and practical man. They may look simple, but double-check your answers before you say you've solved them. If you've got an interesting or unusual answer send it to us. We are especially interested in service stinkers or engineering stumpers on actual electronic equipment. We are getting so many letters we can't answer individual ones, but we'll print the more interesting solutions (the ones the original authors never thought of). We will pay $10 and up for each one accepted. Write EQ Editor, Radio-Electronics, 154 West 14th St., New York, N.Y.

Answers for this month's puzzlers are on page 76.

Voltmeter Puzzle - RF CafeVoltmeter Puzzle

Voltmeters B, C and D show zero volts. What is the voltage reading on voltmeter A and voltmeter E?

- Kendall Collins

 

How Many Diodes?

What is the lowest number of diodes required to obtain full-wave rectification?

- Richard L. Koelker

 

Doubling in Capacitors - RF CafeDoubling in Capacitors

The circuit below is a full-wave doubler bias supply for a push-pull class-AB1 amplifier. If capacitor C1 were to open, what would happen?

- Edward R. Beach.

 

That Four-Bulb Puzzler

A number of our readers have called our attention to the fact that 6-volt (or fractionally higher rating) Zener diodes would give better results in the circuit (March, page 59) than thermistors, since they would not use any power until the bulb failed, and that, when it failed, the voltage drop across the Zener diode would be a closer approximation to that of the bulb than would be the case with a thermistor.

Quizzes from vintage electronics magazines such as Popular Electronics, Electronics-World, QST, Radio-Electronics, 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.

RF Cafe Quizzes

Vintage Electronics Magazine Quizzes

Vintage Electronics Magazine Quizzes

Vintage Electronics Magazine Quizzes

These are the answers.

Doubling in Capacitors Solution - RF CafeDoubling in Capacitors

Nothing much. Removing C1 changes the full-wave doubler to a modified half-wave doubler as shown below.

Ripple would be at 60 cycles instead of 120, and regulation would be poorer. However, since there is virtually no load, output voltage would not change.

Voltmeter Puzzle Solution - RF CafeVoltmeter Puzzle

Two Wheatstone bridges are connected in parallel. To balance the bridges, R1 must equal the internal resistance of voltmeter A and R2 must equal the internal resistance of volt-meter E. The zero reading on voltmeters B, C and D shows that the bridges are balanced. Therefore, the value of 1,000 ohms for R1 shows that the internal resistance of voltmeter A is 1,000 ohms. Also, a value of 1,000 ohms for R2 shows the internal resistance of voltmeter E to be 1,000 ohms. When the internal resistance of voltmeter A and voltmeter E is known, the voltage drop across the meters can be easily calculated. The reading of each voltmeter is 1 volt, equal to the voltage across the meter.

How Many Diodes? Solution - RF CafeHow Many Diodes?

Only one diode is needed, in a quarter-bridge circuit as shown. This circuit, while not efficient, is sometimes used as an instrument rectifier (Conant Labs). For the given conditions, the output voltage is Eout = 1/2 Ein.
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About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2025
Webmaster: Kirt Blattenberger,
   BSEE - KB3UON - AMA92498

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a lady's voice announced "You've Got Mail" when a new message arrived...

Copyright  1996 - 2026

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