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

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

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

__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

__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

__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

__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

__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

__The answers to the Circuit Cellar 264 (July) Engineering Quotient are now available. The problems and answers are listed below, along with a schematic. Problem 1a—Is it possible to transmit on-off (DC) signals between two pieces of equipment in both … Continue reading

__Problem 1—The classic two-transistor astable multivibrator is shown below. Typically, R2 and R3 have at least 10 times the value of R1 and R4. This circuit oscillates, with Q1 and Q2 turning on alternately. From the point in time in … Continue reading

__These are the answers to the EQ questions that appeared in Circuit Cellar 260 (March 2012). Problem 1—In an RS-232 interface, why is the idle or “mark” level a negative voltage? Answer 1—RS-232 was developed in the days when people were connecting … Continue reading

__These are the answers to the EQ questions that appeared in Circuit Cellar 258(January 2012). Answer 1—Q1 and Q2 are wired as a differential amplifier, but in this digital application, it’s probably better to think of them as a current … Continue reading

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