@LearnEmc

LearnEMC helps companies build the in-house expertise they need to ensure their products will meet electromagnetic compatibility requirements.

 Stoughton, WI
LearnEMC.com
Joined March 2017
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EMC Question of the Week: A 1-volt, 2-Ω source is connected to the 50-Ω, 5-pF input of an oscilloscope through 10 nH of inductance. Which of the plots in the figure most accurately represents the voltage waveform measured by the oscilloscope? Answer at learnemc.com/emc-question-of….
An RLC circuit and four possible output waveforms

ALT An RLC circuit and four possible output waveforms

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EMC Question of the Week: A 100-MHz sine wave with a peak-to-peak amplitude of 2 volts is measured with a 50-Ω EMI test receiver. A single narrow-band spike is observed at 100 MHz. What is the quasi-peak amplitude of that spike? Answer at learnemc.com/emc-question-of….
representations of a sine wave in the time and frequency domains

ALT representations of a sine wave in the time and frequency domains

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EMC Question of the Week: 1-kΩ resistors in series with the low-speed inputs of a microprocessor can help a product meet a.) radiated emissions requirements b.) ESD requirements c.) both of the above d.) none of the above Answer at learnemc.com/emc-question-of….
circuit board with components

ALT circuit board with components

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EMC Question of the Week: A 5-MHz square wave has 1-ns transition times and a peak-to-peak amplitude of 1.0 volt. What is the amplitude of the harmonic at 125 MHz as measured on a spectrum analyzer? Answer at learnemc.com/emc-question-of….
time and frequency domain representations of a trapezoidal waveform

ALT time and frequency domain representations of a trapezoidal waveform

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EMC Question of the Week: Each of the four circuits in the figure has a switch that closes at t=0. Which circuit will be the first to develop 9 volts across the capacitor? Answer at learnemc.com/emc-question-of….
Four RC circuits

ALT Four RC circuits

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EMC Question of the Week: What can we conclude from the near-field probe measurement depicted in the photo that shows 40 dB(μV) peaks between 30 and 50 MHz? Full question and answer at learnemc.com/emc-question-of….
near-field probe measurement

ALT near-field probe measurement

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EMC Question of the Week: Which of the following is a visual aid that is useful for analyzing certain transmission line problems in the frequency domain? a) Bounce Diagram b) Triboelectric Series c) Smith Chart d) Bob Smith Termination Answer at learnemc.com/emc-question-of….
a bounce diagram and a partial mapping of the real and imaginary parts of a complex reflection coefficient on a unit circle

ALT a bounce diagram and a partial mapping of the real and imaginary parts of a complex reflection coefficient on a unit circle

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EMC Question of the Week: A shielded twisted pair connects a small sensor board to a controller board. The sensor board has a plastic enclosure. How and where should the cable shield be connected? Full question and answer at learnemc.com/emc-question-of….
A small pcb is connected to a shielded twisted wire pair. Question marks appear in boxes connecting the cable shield to the board ground.

ALT A small pcb is connected to a shielded twisted wire pair. Question marks appear in boxes connecting the cable shield to the board ground.

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EMC Question of the Week: A 1.0-volt, 100-Mbps, single-ended signal driver sends a signal to a matched load on a 1-meter cable. Which of the cable options in the figure is least likely to cause a radiated emissions problem? Answer at learnemc.com/emc-question-of….
a. coax with shield grounded at connector b. coax with shield grounded at source location c. twisted wire pair with one wire grounded at connector d. coax with shield grounded through a 5-mm pigtail

ALT a. coax with shield grounded at connector b. coax with shield grounded at source location c. twisted wire pair with one wire grounded at connector d. coax with shield grounded through a 5-mm pigtail

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EMC Question of the Week: Class II ceramic capacitors (e.g., X7R) are well-suited for a.) DC power bus decoupling b.) AC power bus decoupling c.) high-pass filtering d.) none of the above Full question and answer at learnemc.com/emc-question-of….
Two SMT components mounted on a printed circuit board

ALT Two SMT components mounted on a printed circuit board

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EMC Question of the Week: At 60 Hz, aluminum foil can effectively shield a.) electric fields b.) magnetic fields c.) both of the above d.) none of the above Full question and answer at learnemc.com/emc-question-of….
Depiction of a mouse in a box covered in aluminum foil

ALT Depiction of a mouse in a box covered in aluminum foil

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EMC Question of the Week: How fast can you draw charge from two parallel planes separated by a distance of 0.25 mm when they are initially charged to 1 volt?  Full question and answer at learnemc.com/emc-question-of….
A switch that closes at t=0 causing a short circuit between two planes spaced 0.25 mm apart. The shorting via radius is 0.3 mm. The relative permeability of the dielectric is 4.5. The voltage between the planes was initially 1 volt.

ALT A switch that closes at t=0 causing a short circuit between two planes spaced 0.25 mm apart. The shorting via radius is 0.3 mm. The relative permeability of the dielectric is 4.5. The voltage between the planes was initially 1 volt.

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