Attention:  This website will be intermittently under construction from June to August 2009

Prototype Model #5

Components (left to right)   MicroChip dsPIC30F3012 Micro Controller Fox Electronics H5C-2E 12.000 MHz Crystal Oscillator Dallas Semiconductor DS275 RS232 Transceiver MicroChip MCP6292 OpAmp National Semiconductor LM2595T Simple Switcher Voltage Regulator   Wire Colors Orange = 5Vdd Green = Ground Blue = OpAmp Vref, SPI, Device Programmer I/O Brown/WhiteBrown = 9VAC White/[color] = I/O Signals   Schematic

Design Functions  An AC/AC transformer reduces the voltage of the Power Line input to about 12VAC. 12VAC signal is input to an OpAmp configured as a high gain voltage comparator. The OpAmp generates a square wave output that it transmits to a Micro Controller digital input. The Micro Controller measures the number of 12MHz clock cycles between input leading edges of the power square wave. A PC client application to collects the frequency information from the Micro Controller by RS232. The client application connects with a web service and uploads the data periodically depending on local bandwidth. Each Data record in the upload contains Frequency, Server (NIST) Time, Authorization ID, and PIN.  The Power Frequency Monitor operator can access a Profile record on the web server.  The Profile record contains Location specific information including Local Frequency, Time Zone, Power Grid, Contact EMail address, and options to Download the data in XML format or clear the dataset. A Web Server Application displays live data from all connected Power Frequency Monitors and updates periodically depending on server bandwidth and client connectivity and displays the selected Power Frequencies on a live strip chart.   PHz Monitor - 2007 MicroChip/Circuit Cellar   Note:  The unit displayed on this page is an older version.  The current working version is Model 8c software version 2.8.4 and can be found in the downloads The current work in progress is Model 9, an Ethernet version.