What's Your EQ?
August 1967 Radio-Electronics

August 1967 Radio-Electronics

August 1967 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.

This "What's Your EQ?" (EQ = Electronics Quotient) from a 1967 issue of Radio−Electronics magazine offers just two challenges to your circuit analysis prowess. The first, "Voltage Booster," is a classic black box (although I colored it blue) mystery where you are supposed to figure out what is inside that produces the stated output given a stated input. Spoiler: You'll need to be familiar with vacuum tube characteristics in order to solve it. Unlike with many such circuits, a simple mental substitution of a field effect transistor will not do the job. You might as well not even try "Shifted Tuning" unless you have hands-on experience with tuning mechanisms of the era. Just go straight to the answer, and gain an appreciation for advancements in radio technology. Guys like Mac McGregor dealt with this kind of phenomenon on a regular basis.

What's Your EQ?

Conducted by E. D. Clark

Two puzzlers for the student, theoretician and practical man. Simple? Double-check your answers before you say you've solved them. If you have on interesting or unusual puzzle (with an answer) send it to us. We will pay $10 for each one accepted. We're especially interested in service stinkers or engineering stumpers on actual electronic equipment. We get so many letters we can't answer individual ones, but we'll print the more interesting solutions - ones the original authors never thought of.

Write EQ Editor, Radio-Electronics, 154 West 14th Street, New York, N. Y. 10011.

Voltage booster circuit - RF CafeVoltage Booster

The black box contains a single, common electronic component. It is not a battery, has no moving parts, and does not oscillate. What is it?

- Richard P. Speck

 

 

Shifted frequency tuning - RF CafeShifted Tuning

The dial of a shortwave receiver is shown. A is the high-frequency end; B is the low-frequency end. When tuning from A to B, stations are received at indicated frequencies. Yet when tuning from B to A, stations are shifted to the left. There is no slip or backlash. What causes the shift?

-C. S. S. Shenoi

 

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.

RF Cafe Quizzes

Vintage Electronics Magazine Quizzes

Vintage Electronics Magazine Quizzes

Answers to What's Your EQ?

These are the answers. Puzzles are on page 66.

Voltage booster solution - RF Cafe - RF CafeVoltage Booster

The box contains an ordinary vacuum tube. Electrons leave the hot cathode with enough energy to reach the plate even though it is slightly more negative. In a triode, the grid, rather than the plate, should be used. Using a vtvm, cathode-to-plate voltages up to 2.5 may be obtained. This voltage drops rapidly with load, but short-circuit currents over 100 μA are normal.

Shifted Tuning

The gang capacitor has been lubricated with machine oil. Starting from A (unmeshed blades), the rotor blades are free and the capacitor functions normally. At B (meshed), the blades are in contact with the reservoir of oil. Due to surface tension, oil evenly spreads between rotor and stator plates, acting as a dielectric, increasing the capacitance. Hence station frequencies are shifted. When the gang is tuned back to A, the blades are again free and the oil seeps out, restoring normal capacitance.

 

 

Posted March 15, 2024