Monthly Archives: November 2016

Remote Car Starter Can Drain Car Battery Within a Week

My Montana-based son mentioned that his wife's 2016 Honda CR-V (Figure 1) will not turn-over after sitting in the garage for seven days. No starting problems had occurred prior to early November. Unfortunately, I have had my share of car electrical problems and some of these problems have been hard to find. However, this is a new car and under warranty, so I recommended that he just take it into the dealer. He took the car into the Honda dealer, who told him that this is the result of the current drain imposed on his car battery by his aftermarket remote start system, which was verified to be within specification –the car was operating normally. Continue reading

 
Posted in Batteries | 20 Comments

Angle Measurement Using Roller Gages

I am continuing to work through some basic metrology examples – today's example uses roller gages to measure the angle of a drilled hole (Figure 1). The technique discussed here uses two roller gages and a plug. The plug must fit the hole snugly (i.e. no backlash) as it will provide the surface that we will be measuring. Using this approach assumes that you need a very accurate measurement of a hole's angle as rough measurements can be made using a protractor. Continue reading

 
Posted in Metrology | 2 Comments

Ensuring Stable DC Power Delivery To Switching Loads

I presented a seminar over lunch today on short-range DC power distribution, which I believe is one of the most exciting areas in electronics today. AC power distribution has dominated power engineering since the "War of the Currents" ended with Westinghouse's AC system winning a decisive victory over Edison's DC system back in the 1890s. Starting in 1930s Europe, high-voltage DC distribution has slowly gained a foothold in some long-haul, high power distribution applications, but most power distribution has continued to be dominated by AC. Continue reading

 
Posted in Electronics, Power Over Ethernet | Leave a comment

Radius Measurement Using Roller Gages

This post will demonstrate how to measure the radius of an arc using two roller gages. While I am a very amateur machinist, I have on occasion needed to measure the radius of an arc (i.e. partial circle) and have not been sure how to approach that measurement. It turns out to be simple given two equal diameter roller gages and a surface plate. You can determine by taking one measurement and knowing the roller gage diameter. Continue reading

 
Posted in Construction, Geometry, Metrology | 3 Comments

Ion Propulsion Math

NASA has a project known as Dawn that put a space probe in orbit around the asteroids Vesta and then Ceres. CSPAN presented an excellent Dawn mission briefing given by Marc Rayman, the Mission Director and Chief Engineer. One of the most interesting aspects of the Dawn spacecraft is its use of an ion thruster to maneuver it from one destination to another. This post presents some simple math that can be used to determine some of its key performance characteristics. Continue reading

 
Posted in Astronomy | 3 Comments

Homemade Roof Pitch Protractor

As an amateur carpenter, I am always looking for simple and cheap construction tools. Recently, I have been working on improving my roof framing knowledge. During my reading on this topic, I saw this roof pitch protractor in a Journal of Light Construction (JLC) article . Notice how the template has a handle to make hauling it up a ladder easier. To get an accurate roof pitch, all you need to do is clamp a spirit level onto the template – simple, fast, accurate. Continue reading

 
Posted in Construction | Leave a comment

WW2 Casualty Rates By Country

I recently was watching a documentary on WW2 that mentioned that Greece and Yugoslavia suffered some of highest casualty rates during WW2. While I have read much about WW2, I had not looked at the casualty rates as a percentage of each country's population. I did some quick web searching and found that the Wikipedia has an excellent table summarizing WW2 casualties, which I imported into Excel and sorted by casualty rates. These percentages are mind numbing. While Greece and Yugoslavia suffered terribly, other countries suffered even more. Continue reading

 
Posted in History Through Spreadsheets, Military History | Leave a comment