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

__# Category Archives: Test Your EQ (Engineering Quotient)

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

__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

__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

__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

__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

__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

__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

__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

__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

__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

__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

__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

__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

__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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