A Parallel Port Stepper Motor Driver With Discrete Components
Using PC’s parallel port is a convenient way to control a stepper motor. For unipolar stepper motors, up to two motors can be controlled with the 8bit data line.
Author: kwong
An Isolated MOSFET Serial Port Relay Controller
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…
Building a Degaussing Coil
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 Simplest MOSFET On/Off Switch
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).
My First Few Days With Chrome for Linux Beta
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.
A Hall Effect Magnetic Field Polarity Detector
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.
A Simple Thread Barrier Implementation
Sometimes a group of concurrently running threads may need to rendezvous at a certain point in time before they can further proceed. This situation commonly arises in areas like event simulation, where the events are synchronized via a clock event…
A Simple Program for Finding Palindromic Prime Numbers
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…
CFL Capacitor Problem
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…
Weekend Ubuntu Upgrade
Karmic Koala was released into the wild last Thursday, so naturally I was going to upgrade my desktop installations at home. In this past I had been doing fresh installs whenever there was a new release, since there might be…
Windows Administrative Share With Samba
In a heterogeneous computing environment (e.g. Linux and Windows), it is necessary to use Samba to share files between the Linux systems and Windows systems. Due to the security enhancements in Windows XP SP2 and above however, the administrative share…
An Alternative Illustration of Prime Number Distribution
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.
Why Current EVs Do Not Make Sense From Economical And Environmental View Points
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.
Strange Windows Authentication Behavior
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…
Monodevelop on Ubuntu 9.04
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.