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What's Your EQ?
January 1963 Radio-Electronics

January 1963 Radio-Electronics

January 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.

This set of three circuit analysis challenges appeared in the January 1963 issue of Radio-Electronics magazine. Readers, staff, and even come companies submitted the "What's Your EQ?" (EQ = Electronics Quotient) content. As an example of the latter, Cleveland Institute of Electronics provided "Draw the Waveform." Don't let the diode vacuum tube deter you from the puzzle. Just mentally replace the tube with a solid state diode symbol with the anode at the top where the tube's plate (anode) is shown. The negative element of a tube is called the cathode, same as the solid state diode. "Capacitor Charge" is easy enough. "Another 2-Box Light" is a form of Black Box problem. Don't be afraid to think outside the box to figure out what is going on inside the box!

What's Your EQ?

"What's Your EQ?, January 1963 Radio-Electronics - RF CafeDraw the Waveform - RF CafeDraw the Waveform

The sine wave with a peak value of 30 volts, shown at the input of circuit, collided with a diode on its way to the output. As a result, the wave was bent a bit. Draw in the space provided the shape of the wave at the output. Ignore the voltage drop across the diode.

- Cleveland Institute of Electronics

 

Capacitor Charge Solution - RF CafeCapacitor Charge

Two 1-μf capacitors are connected in series with a 100-volt dc source. A shorting switch is connected across one of the capacitors. The capacitors are both good. The shorting switch is pressed, then released. What is the condition of the charge on the two capacitors immediately after the shorting switch is released?

- V. H. Laughter

 

Another Two-Box Light - RF CafeAnother Two-Box Light

Each of the boxes has an spst switch throw and a 120-volt 6-watt indicator lamp with jewel. The wires are shown in the diagram. The switch in each box operates the lamp in the opposite box. The boxes are a little larger than is necessary to enclose the single-pole single-throw switch and the 120-volt lamp and its socket. What is the circuit? What is in the boxes?

- Almon H. Clegg

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

Answers to What's Your Eq?

These are the answers!

Draw the Waveform Solution - RF CafeDraw the Waveform

As long as the input signal is less than +20 volts, the diode cannot conduct and the output signal is the same as the input signal. When the input voltage reaches 20, the tube acts as a short, keeping the voltage from rising any higher.

Capacitor Charge

Since the two capacitors are In series, the 100-volt charge will divide, charging each to 50 volts. When the shorting switch is pressed, the non-shorted capacitor (C1) will be charged to 100 volts. When the switch is released, one end of C2 is connected to the negative side of the battery and the other end to the negatively charged end of C1. Thus, you will have a 100-volt charge on one capacitor and zero charge on the other. (This statement does not consider the residual charge left in the shorted unit.) Due to leakages, the charges will gradually even up, resulting in a final charge of 50 volts on each capacitor.

Another Two-Box Problem Solution - RF CafeAnother Two-Box Problem

As you have probably guessed, this is also done with rectifiers, and the difference between it and the earlier problems is in the switching. The diagram below shows the circuit. The lamps are 120 volts 6 watts, as stated in the problem, and the rectifiers should be rated at 100 ma or more.

About RF Cafe

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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...

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