Issue 308: EQ Answers

EQ

Problem 1—The circuit shown below is an audio amplifier with a slightly unusual topology. Explain how to analyze its DC operating point.  Answer 1—For the DC analysis, start by calculating the Thevenin equivalent of the bias network: 8.0 V and 16.67 kΩ. … Continue reading






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Issue 304: EQ Answers

EQ

Problem 1—The following circuit was designed to be an inrush current limiter for the large (40,000 µF) capaitor C1. R7 represents the application load of about 180 mA at 9 V. The load on the 9-V source (Vin) needed to … Continue reading






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Issue 302: EQ Answers

EQ

Problem 1: You have decided to build a small computer from discrete transistors as a demonstration. After researching the available technologies, you have decided to base your design on NMOS logic, using a 3-input NOR gate as your basic building block, … Continue reading






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Issue 300: EQ Answers

EQ

Problem 1: The diagram below is a simplified illustration of a switchmode “buck” DC-DC converter with synchronous (active) rectification. The switching elements are shown as MOSFETs, with the associated body diodes drawn explicitly. The details associated with driving the MOSFET gates … Continue reading






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Issue 298: EQ Answers

EQ

Problem 1: What do we call a network of gates that has no feedback of any kind? What is its key characteristic? Answer 1: A network of gates that has no feedback is called “combinaotorial logic”, or sometimes “combinational logic”. Its defining characteristic … Continue reading






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Issue 296: EQ Answers

EQ

Answer 1—The frequency generated at the QB output of the counter is 16.000 MHz × 3 / 13 = 3.6923 MHz. The ratio between this and 3.6864 MHz is 1.0016, so the error expressed as a percentage is +0.16%. This is well within … Continue reading






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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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