Archive for the ‘Miscellaneous’ Category.
February 4, 2010, 9:48 pm
Using DTR (data terminal ready) and RTS (request to send) pins of a PC serial port (RS-232) without actually using the serial data pins, we can interface at least two relay devices with a computer. Windmeadow Labs has an excellent article on how to achieve this using a bipolar transistor (BJT). Here I will show you a similar relay control circuit built using an opto-isolator and a MOSFET. Continue reading ‘An Isolated MOSFET Serial Port Relay Controller’ »
January 18, 2010, 10:27 pm
One of my older CRT TVs does not have a built-in degauss button and after sitting in the corner of the basement for a couple of years, it somehow got magnetized pretty badly. The top two-thirds became totally disclorored with the “rainbow” effect. Continue reading ‘Building a Degaussing Coil’ »
January 6, 2010, 7:46 pm
A touch sensitive on/off switch can be made with a single MOSFET. The following schematics illustrate such a switch using only a power MOSFET (IRFZ22). Continue reading ‘The Simplest MOSFET On/Off Switch’ »
December 13, 2009, 10:02 pm
When Google Chrome beta for Windows was first released last September, I tested it briefly on a Windows XP box and was quite impressed by its speed and simplistic user interface. Continue reading ‘My First Few Days With Chrome for Linux Beta’ »
December 5, 2009, 8:42 pm
Hall effect sensors can be found in many common household gadgets. Most brushless DC motors for instance, like those used in computer cooling fans, contain Hall effect sensors in the driving circuits. Continue reading ‘A Hall Effect Magnetic Field Polarity Detector’ »
November 15, 2009, 9:49 pm
A palindromic prime (palprime) is a prime number that is also palindromic. So out of curiosity I wrote a simple program a few days ago that can find the palindromic numbers within a given range. Here is the code in C++: Continue reading ‘A Simple Program for Finding Palindromic Prime Numbers’ »
November 8, 2009, 10:03 pm
Many of you may still remember the capacitor plague that caused massive motherboard failures back in the early 2000s. While the practice of using cheap and unreliable electrolytic capacitors in computer components has largely died down nowadays, it seems that the issue has cropped up elsewhere. Continue reading ‘CFL Capacitor Problem’ »
September 6, 2009, 10:40 am
Prime number theorem dictates the asymptotic behavior of prime number distributions. In layman terms, the distance between prime numbers increases at a logarithmic pace. This gives the familiar logarithm figure. Continue reading ‘An Alternative Illustration of Prime Number Distribution’ »
August 15, 2009, 7:32 pm
About two years ago, I blogged about why hybrids were not saving us any energy by taking into consideration the amount of energy needed to produce the vast battery packs and the inherent low efficiencies in battery technologies. Continue reading ‘Why Current EVs Do Not Make Sense From Economical And Environmental View Points’ »
July 30, 2009, 8:13 am
I was writing an ASP.Net 2.0 web application using Windows authentication (since I needed to capture users’ credentials). The web application saves data into a MS SQL 2005 database using a SQL server account. While developing this application, I ran into a very strange issue. Continue reading ‘Strange Windows Authentication Behavior’ »
July 22, 2009, 12:00 am
I am running Ubuntu 9.04 64bit. One thing I noticed is that the integrated debugger is behaving quite flaky for the included Monodevelop 2.0 package. After some research, it turned out that a lot of people are having similar issues. Continue reading ‘Monodevelop on Ubuntu 9.04’ »
July 6, 2009, 9:43 pm
It appeared that Google Finance was down for at least half an hour (from before 9:30 EST till after 10:00 EST) today. I captured this screen-shot during the outage: Continue reading ‘Google Finance Down Earlier Today’ »