Laptop to PA humming

A quite typical audio/visual presentation equipment nowdays in many setups includes PC, video projector, audio mixer, amplifier and speakers. Typically you run presentation software through our laptop to a projector and the audio from mics, pianos, guitars, etc to a mixer and then to power amps then to the speakers. The problem many people are

Neutral wire grounding

An ungrounded system is one in which there is no intentional connection between the system conductors and earth. When the neutral of the system is not grounded, it is possible for high voltages to appear from line to ground during normal switching of a circuit having a line to ground fault. These voltages may cause

Scope and ground loops

Differential Scope Primer is a good introduction to oscillospe measurement. This web posting is a shortened version of the information on that document related to ground loops. I have also added here some of my own comments. Most oscilloscopes are designed to measure voltages that are referenced to earth ground, which is connected to the

Power Quality and Utilisation Guide

Power Quality and Utilisation Guide is a free on-line reference source for power quality information. It provides both background theory and solutions from electrical power industry. The guide is prepared by specialist authors from industry and academia, and edited by Copper Development Association‘s David Chapman. The Guide is organized into 8 sections and presented in

EMC fundamentals and groundloops

Some days ago read Things Every Electrical Engineer Should Know about EMC slide set by Todd H. Hubing Michelin Professor of Vehicular Electronics Clemson University. I must say that it is an interesting slide set to check. It is a short 25 slide set that introduces EMC fundamentals and ground loops. Here is one fact

Manager’s guide to digital design

Manager’s guide to digital design article from EDN magazine is for all those hardworking engineering managers who just want a simple, one-page summary of everything they need to know about digital design. Here are some picks from article: GROUND: mythical electrical object that absorbs unlimited quantities of electrical current. Ground exists in Spice but nowhere

Unbalanced to impedance balanced

Just about all professional equipment uses balanced audio lines, which, if properly executed, will eliminate the hum completely. They help especially with long interconnects where earth loops can be a real pain. Circuits driving balanced lines must themselves be balanced to maintain the benefits of balance. This may be achieved by differential signaling, transformer coupling

High Speed Lightning Videos

Lightning Reveals Its Power in Slow Motion article on Wired has a series of videos that combines severe weather, electricity, and technology. The maker of those videos, Tom Warner, documents the powerful beauty of lightning with an array of optical and electromagnetic sensors. “Lightning is one of nature’s most spectacular phenomena,” says Warner. “I want

Differential video amplifiers

Differential amplifier approach uses an operational Amplifier. Operational Amplifiers only amplify the difference between the two input lines. This method eliminates common mode noise between the incoming signals by making A-B=C, as only the difference between A & B are amplified. Operational amplifiers is maintain wide bandwidth signals throughout your system while eliminating ground loop