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What's Your EQ?
August 1961 Radio-Electronics

August 1961 Radio-Electronics

August 1961 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.

Three new "Electronics Quotient" (EQ) puzzles await your solving, these from the August 1961 issue of Radio-Electronics magazine. The first, "A Lighting Problem," is fairly simple. You'll need to think out-of-the-box to figure out what is in-the-box. If I got it, you can get it. The second puzzler, "Resistor Mixup," is yet another variation on a common attempt to throw the reader off by configuring the connections in a nonconventional manner. By the way, you might remember to use the same technique to assess actual schematics when attempting to figure out what is going on in a "real" circuit. It seems to me whenever not enough EQs are received from readers, Jack Darr, of R-E's "TV Service Clinic" column fame, is solicited for one of his TV troubleshooting challenges. Being in the prehistoric Vacuum Tube Age (~1906-1966), his circuits nearly always involved tubes and complex analog waveforms. Anyone born after about 1970 may skip this problem ;-)

What's Your EQ?

We've been swamped! Each day the post office delivers so much mail for our EO column that we've had trouble keeping up with it. We're happy to learn so many of our readers are interested in the puzzles, but we just won't be able to answer any individual letters. We will publish any interesting solutions we receive.

Our black box problem this month is a little different, it has two black boxes instead of one. And the TV stinker is a little more difficult than usual.

Send us more problems on the engineering level - we have plenty of TV and general ones, $10 and up will be paid for each one accepted. Write to EQ Editor, Radio-Electronics, 154 West 14th St., New York 11, N, Y.

Answers to July puzzles are On page 75. Answers to this month's puzzles appear next month.

A Lighting Problem - RF CafeA Lighting Problem

Two boxes are connected by a single wire. A lead runs from each box to an ac source. On the first box are mounted two bulbs; on the second a single-pole, three-position switch. In the first position of the switch, the red bulb glows; in the second, the blue one glows, and in the third position, both bulbs light. What is the simple circuitry in the two boxes that performs this bit of "magic"?

 - Charles B. Randall

 

Resistor Mixup

Resistor Mixup - RF CafeThis apparently simple problem in resistance becomes more confusing as you study it. Find the effective resistance of this circuit.

- Fred W. Blakeley

 

Yuletide Effect

Yuletide Effect - RF CafeSymptoms: Horizontal oscillator in a Truetone 2D1235A squegged, and made "Christmas trees" all over the place. No high voltage at all. Tubes and all parts OK.

Clues: If horizontal oscillator coupling capacitor is disconnected from horizontal output stage, output stage can be driven to full output, plenty of high voltage and brightness, by using external horizontal drive pulse from tester. If horizontal output is driven in this way to bring boost voltage up, horizontal oscillator then puts out perfectly shaped, locked-in-sync waveform. If the two are re-connected, waveform at horizontal output tube grid looks like drawing - almost as if a color burst were being added to the slope of the waveform - and whole thing won't work.

Hint: The oscillator and output stages will work separately and all parts are good, but the two won't work together.

- Jack Darr

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

Solutions

A Lighting Problem

Yuletide Effect (solution) - RF CafeThe switching is accomplished by an arrangement of rectifying diodes. In position 1, the positive pulse from the ac generator is passed through the single wire into the box with the bulbs. This pulse is accepted only by the rectifier hooked up in the same polarity and blocked by the other rectifier, the resulting current flow lighting the red bulb. In position 2, the opposite occurs and the blue bulb lights. In position 3, pure ac is passed into the first box and both bulbs light, one from the position pulse and the other from the negative pulse.

Resistor Mixup

Answer: Actually all the resistors are connected in parallel. Therefore, the effective resistance is 8 ohms .

Yuletide Effect

The 80-μf electrolytic capacitor in the output of the B-supply filter is defective. It had an extremely high power factor, coupled with a severe loss of capacitance, although there was no perceptible hum in the sound. This allowed the horizontal oscillator to receive peaks or pulses probably fed back through the boost in some way and caused it to break into sporadic oscillation on each cycle. This broke up the time-constant circuits in the yoke, etc., and stopped the output stage from functioning properly.

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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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