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.
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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.
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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).
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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.
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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.
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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 (see illustration below):
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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++:
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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.
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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 some issues with the new Ext4 file system, I decided to upgrade my current 9.04 installation in place and perform a fresh installation when the Ext4 file system stabilizes.
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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 access (e.g. \\{computer name}\c$ is disabled by default.
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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.
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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.
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