John La Grou Sacramento Valley Audio Engineering Society 2/ 21/ 09
John La Grou of Millenia Media started off his presentation with a history of the microphone preamplifier. Topics such as the voltage gain ratio of a pre-amp, Alexander Graham Bell's human ear microphone and liquid telephone were covered. The definition of measurement units such as decibels, ampheres, and current were also covered. Differences between vacuum tubes, discrete transistors and integrated circuits (as well as thier applications in audio) were also discussed. Common design features of a pre-amp were then covered including the main gain stage, output stage, overload & RF protection, polarity reversal, impedance, etc. The double balanced microphone amplifier design was also discussed followed by a brief Q&A session. The Millenia HV-3R architechure was then discussed including componet choice/placement and circuit design. John then concluded his presentation with a discussion on his newest venture, a smart EFCI electrical safety receptacle. This EFCI works much like the EFCI outlets already installed in most homes with one major difference, it uses RFID chip technology to help it sense overload conditions. Basically, the trip level of the receptacle(s) in a smart EFCI outlet is determined by the information sent from an RFID chip embedded in an electrical device's plug. Once an overload condition is detected, the outlet will shut down the corresponding receptacle(s). This technology can also be used to remotely access and shut down specific outlets/receptacles in your home (ie. you went on vacation and forgot to turn off your personal space-heater).
