Conducted Emissions on the Bench: Implementing the CISPR 25 Voltage Method

Complete CISPR 25 (voltage method) benchtop test setup

This article pulls back the curtain on CISPR 25 conducted-emissions testing, demonstrating how a fully functional voltage-method setup can be built and operated on a standard lab bench. This approach shows how conducted emissions can be characterized with precision using accessible tools and a carefully structured setup, while walking through all critical elements needed to … [Read more…]

DIY Spark Gap Transmitter

Simple spark gap transmitter built from a handful of components on a acrylic glass base

This article plunges you into the mesmerrizing world of early radio technology through the assembly and analysis of a DIY spark gap transmitter. This project offers a practical insight into the fascinating dynamics of damped harmonic oscillators and explains charasteristics such the logarithmic decrement, decay rate, damping factor, q factor, and beyond. Prepare to spark your curiosity in a technology that once revolutionized global communication.

DIY: Adjustable 30 kV High Voltage Power Supply

Spark-gap transmitter used for testing the high voltage power supply

High voltage power supplies can open interesting doors to research topics such as laser, x-ray, spark gap transmitters. And many other specialized niches. Unfortunately, laboratory grade high voltage power supplies are rather costly. Luckily, there is a much less expensive way to put high voltage experiments into the hobbyists reach. This article shows how to build an inexpensive and adjustable 5 kV to 30 kV high voltage supply from a commercial laser supply.

Critical length of a PCB trace and when to treat it as a transmission line

SAW filter PCB with SMA connectors for 1090 MHz (ADS-B). Mismatched input and output traces (Z=100 Ohms, l=3,5mm) have been deemed acceptable.

Ideally, the impedance of PCB traces should be matched to the load and source impedances. This becomes especially important in high-frequency and high-speed digital PCB designs. Various rules of thumb are available to determine the critical length at which a PCB trace should be treated as a transmission line. Below this critical length, an impedance mismatch can safely be ignored. Or can it?