Author Archives: mathscinotes

Handling "Hot" Electronics Requires Gloves

Posted on 9-July-2012 by mathscinotes

I have had a number of equipment installers contact me this summer and express concerns about the temperature of the outdoor electronics that they are handling. In some cases, the electronics is too hot to hold. In every case, the … Continue reading →

Posted in Electronics | Tagged , | 2 Comments

Some Empirical Potentiometer Results

Posted on 26-June-2012 by mathscinotes

Just a note that I have added some empirical test results to the following three posts on potentiometers. "Logarithmic" approximation using Linear pot with shunt resistances Square law circuit Opamp-based circuit

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Cost of Cooling Electronics

Posted on 26-June-2012 by mathscinotes

Introduction One of my favorite physicists stopped by today and wanted to talk about the cost of cooling electronics like fans and air conditioners. The talk was somewhat mathematical and worth discussing here because the basic math is what a … Continue reading →

Posted in Construction, Electronics | Comments Off on Cost of Cooling Electronics

Yet Another Circuit with a "Logarithmic" Characteristic

Posted on 18-June-2012 by mathscinotes

Introduction While I was looking for different circuits that generate a logarithmic characteristic (voltage, current, or resistance), I stumbled upon a web page that discussed a logarithmic potentiometer approximation using a linear potentiometer with one or two resistors connected to … Continue reading →

Posted in Electronics | Tagged | 1 Comment

Wall-Wart Math

Posted on 7-June-2012 by mathscinotes

I have had some questions recently on the power conversion efficiency of AC power adapters (aka "wall warts"). I think my customers are becoming more concerned about energy costs. The questions that I received focused on how the efficiency of … Continue reading →

Posted in Electronics | 2 Comments

Product Feature Presentations Using Excel's AutoFilter and VBA

Posted on 5-June-2012 by mathscinotes

I have to present a lot of data to people, but I find PowerPoint, a corporate workhorse, to be a poor vehicle for presenting data. I am not an acolyte of Tufte -- a famous PowerPoint critic -- I just … Continue reading →

Posted in Management | Comments Off on Product Feature Presentations Using Excel's AutoFilter and VBA

Computer Museum in Bozeman Montana

Posted on 25-May-2012 by mathscinotes

I am currently in Bozeman, Montana, and I just took a tour of the "Museum of Modern Human Progress," formerly known as the American Computer Museum. I was with one of my sons, and the museum provided us a great … Continue reading →

Posted in History of Science and Technology | Tagged | 4 Comments

Square Law Potentiometer Circuit

Posted on 25-May-2012 by mathscinotes

I do not have an immediate need for a circuit that generates an output voltage proportional to the square of the potentiometer setting, but this circuit was interesting enough that I thought I would document it here. I found it while looking for a logarithmic potentiometer circuit. Continue reading →

Posted in Electronics | 5 Comments

Another Circuit with a "Logarithmic" Characteristic

Posted on 23-May-2012 by mathscinotes

Electronics is my profession and my hobby (along with mathematics). For a hobbyist project of mine, I need an amplifier circuit with a programmable gain that varies exponentially with the setting on a potentiometer. When I design a circuit, I usually begin my design effort with a web search. I do not like reinventing the wheel. I found an old EDN article that has an interesting circuit, but the figures are not visible. I will reconstruct the circuit here based on the text description and make a small modification that makes it a bit more appropriate for my application. Continue reading →

Posted in Electronics | Tagged | 7 Comments

High Definition Television Bandwidth and Compression Math

Posted on 15-May-2012 by mathscinotes

As part of my job, I actually encountered one person who regularly watches 14 simultaneous HDTV feeds. He is a stock trader who works out of his home. He was displaying stock data from multiple markets on multiple televisions. Think about it -- 14 · 20 Mbps = 280 Mbps of television being watched by one person. Continue reading →

Posted in Electronics | 9 Comments