The switching power supplies that regulate output voltage produce radiated emissions. Our tests compare waveforms that give clues as to how the chargers operate.
oscilloscope measurements
Characterize EMI from dc-dc converter ringing
Switching power supplies produce radiated and conducted emissions caused by ringing. Oscilloscope and spectrum-analyzer measurements let you see them. DC-DC converters are ubiquitous in most electronic products. While more efficient than linear regulators, they can also produce considerable amounts of interference that can affect nearby circuits. The measurements in this article show how ringing occurs […]
Review: PCBite circuit board holder and probe kit
The PCBite kit holds your circuit board in place while you probe it, reducing the risk of short circuits. Recently, I’ve had to test and characterize many small PC boards, including embedded processors, DC-DC converters, and other wireless-related products, for EMC issues. I’ve never really had an easy way to keep these boards from moving […]
How to calculate and apply the inverse discrete Fourier transform: part 4
In part 3 of this series, we used the inverse fast Fourier transform (IFFT) to create 100-Hz time-domain waveforms of various amplitudes and phases. We can also use the IFFT to create waveforms containing multiple frequencies. If you look closely at Figure 1 in part 1 of this series, you’ll notice that the time-domain waveform […]
Tryout: Uni-T UPO1202 200 MHz oscilloscope
You need not spend a ton of money to get a feature-packed oscilloscope, provided you don’t need high bandwidth. While the oscilloscope works well, the free software needs help. After seeing the Uni-Trend (Uni-T) UTG962E Function/Arbitrary Waveform Generator ($182), we at EE World bought one and, at the same time, ordered a UPO1202 200 MHz […]
How to calculate and apply the inverse discrete Fourier transform: part 3
The inverse transform can create a time-domain waveform where no waveform has been before. In part 2 of this series, we used the discrete Fourier transform to convert a waveform from the time domain to the frequency domain, operated on the frequency-domain data, and used the inverse transform to reconstruct the altered time-domain waveform. That’s […]
How to calculate and apply an inverse FFT: part 2
In part 1 of this series, we looked at the formula for the inverse discrete Fourier transform and manually calculated the inverse transform for a four-point dataset. Then, we used Excel’s implementation of the inverse fast Fourier transform (IFFT) to verify our work. Could we try something more realistic? Sure. We can take a signal […]
Isolated current probes eliminate ground loops
IsoVu isolated current probes from Tektronix isolate oscilloscopes from circuits used for EVs, motors, and power converters. Trying to make shunt-based current measurements with a typical oscilloscope probe is essentially impossible. That’s because one side of the probe connects to ground through the instrument. Using an ungrounded power cord is anything but safe. Differential probes […]
USB oscilloscopes add automotive 10Base-T1S protocol analysis
Pico Technology, a manufacturer of USB oscilloscopes, has added 10Base-T1S protocol analysis to software that operates the company’s line of USB oscilloscopes. That brings to 40 the number of serial protocols that the company supports. PicoScope 7 software is a free download. 10Base-T1S is a two-wire Ethernet standard that specifies a physical layer for automotive […]
High-impedance, high-bandwidth oscilloscope probe captures serial bus signals
The Infiniimax 4 active probe from Keysight reaches 52 GHz, enough to see signals on PCIe 6/7, 800 Gb/sec Ethernet, DDR 5/6, and other high-speed serial buses. Oscilloscopes with 100 GHz and higher bandwidths can display signals on 224 Gb/sec PAM4 serial buses and they’ve been available for several years. Without probes of high enough […]
