Issue 294: EQ Answers

EQ

Problem 1—Let’s get back to basics and talk about the operation of a capacitor. Suppose you have two large, flat plates that are close to each other (with respect to their diameter). If you charge them up to a given … Continue reading

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Issue 292: EQ Answers

EQ

Problem 1—Let’s talk about noise! There are different types of noise that might be present in a system, and it’s important to understand how to deal with them. For example, analog sensors and other types of active devices will often … Continue reading

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Issue 290: EQ Answers

EQ

Problem 1—What is an R-C snubber, and what is a typical application for one? Answer 1—An R-C snubber is the series combination of a resistor and a capacitor that is placed in parallel with a switching element that controls the … Continue reading

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Issue 288: EQ Answers

EQ

Problem 1—When designing a pair of band-splitting filters (for, say, an audio crossover), why is it important to match frequencies of the –3-dB points of the low-pass and high-pass responses? Answer 1—The cutoff frequencies of the two filters should be … Continue reading

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Issue 286: EQ Answers

EQ

Question 1—A divider is a logic module that takes two binary numbers and produces their numerical quotient (and optionally, the remainder). The basic structure is a series of subtractions and multiplexers, where the multiplexer uses the result of the subtraciton … Continue reading

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Issue 284: EQ Answers

EQ

PROBLEM 1 Can you name all of the signals in the original 25-pin RS-232 connector? ANSWER 1 Pins 9, 10, 11, 18, and 25 are unassigned/reserved. The rest are: Pin Abbreviation Source Description 1 PG – Protective ground 2 TD … Continue reading

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Issue 282: EQ Answers

EQ

PROBLEM 1 Construct an electrical circuit to find the values of Xa, Xb, and Xc in this system of equations: 21Xa – 10Xb – 10Xc = 1 –10Xa + 22Xb – 10Xc = –2 –10Xa – 10Xb + 20Xc = … Continue reading

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Issue 280: EQ Answers

EQ

PROBLEM 1 What is the key difference between the following two C functions? #define VOLTS_FULL_SCALE 5.000 #define KPA_PER_VOLT 100.0 #define KPA_THRESHOLD 200.0 /* adc_reading is a value between 0 and 1 */ bool test_pressure (float adc_reading) { float voltage = … Continue reading

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Issue 278: EQ Answers

EQ

Problem 1—Tom, an FPGA designer, is helping out on a system that handles standard-definition digital video at 27 MHz and stores it into an SDRAM that runs at 200 MHz. He discovered the following logic in the FPGA (see Figure … Continue reading

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Issue 276: EQ Answers

EQ

Problem 1 Suppose you have an ordinary switch mode buck regulator. The input voltage is 100 V, the switch’s duty cycle is exactly 50%, and you measure the output voltage as 70 V. Is this converter operating in continuous conduction … Continue reading

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Issue 274: EQ Answers

The answers to the Circuit Cellar 274 Engineering Quotient are now available. The problems and answers are listed below. Problem 1—What is wrong with the name “programmable unijunction transistor?” Answer 1—Unlike the original unijunction transistor—which really does have just a … Continue reading

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Issue 272: EQ Answers

The answers to the Circuit Cellar 272 Engineering Quotient are now available. The problems and answers are listed below. Problem 1—Why does the power dissipation of a Darlington transistor tend to be higher than that of a single bipolar transistor … Continue reading

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Issue 270: EQ Answers

The answers to the Circuit Cellar 270 Engineering Quotient are now available. The problems and answers are listed below. Problem 1: Given a microprocessor that has hardware support for just one level of priority for interrupts, is it possible to … Continue reading

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Issue 268: EQ Answers

Problem 1: A transformer’s windings, when measured individually (all other windings disconnected), have a certain amount of inductance. If you have a 1:1 transformer (both windings have the same inductance) and connect the windings in series, what value of inductance … Continue reading

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Issue 266: EQ Answers

EQ

The answers to the Circuit Cellar 266 (July 2012) Engineering Quotient are now available. The problems and answers are listed below. Problem 1—What’s the key difference between infinite impulse response (IIR) and finite impulse response (FIR) digital filters? Answer 1—An … Continue reading

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