June 1963 Popular ElectronicsTable of Contents
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Popular Electronics was published from October 1954 through April 1985. All copyrights are hereby acknowledged. See all articles from Popular Electronics.
Having worked around resistors and capacitors for more than four decades comes in handy when presented with 'simple' quizzes like this one that appeared in a 1963 Popular Electronics dealing with RC circuits. Still, there is always some trepidation involved when being subject, even voluntarily, to a test of any sort, regardless of whether you are fairly confident that it will be a lead pipe cinch, a cake walk, child's play, so to speak. Even if nobody else will bear witness to your effort, you would feel like a real moron if you missed even one of those simple questions that anyone with your level of experience should get right without even having to think about it. Such is the irrational fear I have when taking these quizzes prior to posting them on RF Cafe. I have always been honest about the results, and there have been instances where I missed a couple that I shouldn't have by all rights (or wrongs). This time, however, Lady Luck was with me and I aced it. If you're not accustomed to seeing those strange round schematic symbols with a mix of solid and dashed horizontal lines within, those are vacuum tubes. Just mentally substitute your favorite solid state amplifier like a bipolar of a field effect transitor.
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Circuits that are made up of resistors and capacitors only perform a wide variety of functions in electronic equipment. Try to match the RC circuit functions listed (1-10) with the circuits (A-J) to which they apply.
Answers are at the bottom of the page.
1 Decoupling network ____
2 Treble-cut tone control ____
3 Differentiator ____
4 Frequency control ____
5 Phase-shifting network ____
6 Timing control ____
7 Equalizer ____
8 Integrator ____
9 Band suppression filter ____
10 RC coupling circuit ____
|Here are other Popular Electronics quizzes:|
- Lamp Brightness Quiz, January
RC Circuit Quiz Answers
1 - D - A Decoupling Network acts as a low-pass filter so that
signal frequencies are bypassed to ground
and not coupled to other stages via the power supply.
2 - A - A Treble-cut Tone Control in the plate circuit of an
audio amplifier acts as a low-pass filter. Decreasing
the amount of resistance bypasses an increasing amount of the highs to ground.
3 - G - A Differentiator is a high-pass filter which removes
low-frequency components of a square wave.
Capacitor charges very quickly and permits only short pulses of current through resistor.
4 - J - The Frequency Control circuit for this blocking oscillator
biases the transistor to cutoff until the capacitor
has discharged through the resistor. The capacitor then charges up again through the transistor when
it begins to conduct.
5 - F - The Phase-Shifting Network to provide in-phase (positive)
feedback for this oscillator consists of three
cascaded RC circuits, The voltage across each resistor leads the signal applied to each RC section
by 60 degrees.
6 - E - The Timing Control for this time delay circuit is an
RC circuit which controls the transistor emitter-base
biasing. The relay remains energized until the capacitor is charged and opposes the forward bias
provided by the battery.
7 - I - An Equalizer for a crystal phonograph cartridge is a
low-pass filter designed to compensate for the
attenuation of low frequencies in disc recordings.
8 - B - An Integrator is a low-pass filter which removes high
frequencies from a square wave, In this
long-time-constant circuit, the capacitor charges and discharges slowly through the resistor.
9 - C - A Band Suppression Filter such as this Wien bridge contains
both series and parallel RC circuits which
balance with the resistive arms to null the output signal at a particular frequency.
10 - H - An RC Coupling Circuit is really a form of high-pass
filter; capacitor must be large enough in proportion
to resistor to pass the lowest signal frequency without excessive attenuation.
Posted April 22, 2014