Past Columns

Start‑up transients can hide major EMI and reliability problems. By capturing inrush current spikes and high‑frequency events with high‑bandwidth scopes and probes, engineers can uncover failures, resets, and random behavior caused by fast di/dt during power‑up—and design effective fixes.

There always seem to be questions about hi-pot testing. Maybe I can present some of those questions and their answers.

Why do cables radiate? Common mode currents are the culprit. Through four practical experiments, learn how return paths, grounding switches, and parasitic capacitances determine whether your current stays differential—or becomes a radiating common mode problem.

How does safety work? That is, given a hazardous situation, how do we prevent injury from that situation?

When testing EMI performance, substituting real loads with "equivalent" resistors can mislead you by up to 20dB—enough to turn a passing design into a costly failure. This practical guide demonstrates why fans, motors, and other non-linear loads behave dramatically differently than resistors, and why authentic testing matters for accurate results.

Parasitic oscillations are a sneaky source of EMI/EMC failures. With the right layout and simple fixes—like reducing gain or breaking feedback loops—you can eliminate emissions without costly redesigns. Learn how to spot and stop these hidden troublemakers in your circuit.

Did you ever wonder why we use 0.1 ohm (and sometimes 0.5 ohm) for the ground impedance value for plug-and-socket connected equipment?

The “power distribution system” is all parts of an electric system between the “bulk power source” and the consumer’s service-entrance equipment.

High-quality inductors and capacitors can create dangerous resonant circuits, generating voltage peaks up to Q times the input voltage. This underdamped behavior causes EMI issues, component damage, and circuit malfunctions. Strategic damping with resistors or ferrites provides effective solutions for power integrity problems.

After causing a bit of a stir in the compliance testing industry in the last few years, the FCC recently defused some tension when they accepted a pair of US-based Accreditation Bodies to accredit laboratories in foreign lands.