Archive for the ‘Miscellaneous’ Category.
Modified sine wave is essentially just a pulse width modified square wave. It is a very useful waveform for power inverters. Compared with the simplest inverters with square waveform, inverters using modified sine wave can compensate the output voltage by simply changing the pulse width (duty cycle) of the waveform. Continue reading ‘Modified Sine Wave Generation With AVR’ »
I recently bought a TrendNet TK-207K KVM switch. After hooking up my mouse and keyboard, I was suprised to find out that the setting did not work. The mouse and keyboard would act strangely and sometimes one would stop working altogether. At first, I thought that I might have gotten a defective unit. But I quickly realized that it was a power issue — The USB port was not able to provide sufficient power to both my mouse and my keyboard. Continue reading ‘Simple External Powered USB Port’ »
Continue with my previous article, let me first explain the code a little bit. Continue reading ‘4KHz-170MHz Wide Band RF Signal Generator – II’ »
When working with micro-controller projects, it is often necessary to perform calculations in binary and hexadecimal forms. While almost all calculator tools (such as calc under Windows and gcalctool in Linux) can handle such tasks, they are designed for general purpose calculations and not geared specifically towards working with digital circuits. Continue reading ‘Hex/Bin/Dec Converter And Calculator’ »
Field strength meter is extremely useful when working with RF devices. It can be used to quickly diagnose whether a transmitter circuit is working, and can be used to detect RF signals in the environment. Continue reading ‘Wide-band RF Field Strength Meter’ »
I used to own an all-transistor, single channel 10 MHz analog oscilloscope. While it was not adequate by nowadays standard, it served me quite well for many years. The scope was later sold and I had been thinking about getting a new oscilloscope for quite a while. This time around though, I wanted to get a digital storage oscilloscope (DSO) since in many cases, it is a lot more convenient to use. After reading about some rave reviews on Dave Jone’s EEVBlog about this Rigol DS1052E scope, it became apparent that this would be the ideal scope for my workshop. So without much hesitation, I ordered one. Continue reading ‘My New DS1052E Oscilloscope’ »
Well, there is an old saying:“There’s no such thing as a free lunch.” After yesterday’s server upgrade, everything worked pretty well till sometime late this afternoon. Continue reading ‘Weekend Server Upgrade – Update’ »
I have finally got around to upgrade my web server. The server I have been using was an old Pentium III about 10 years old. It had been serving my website quite well over the years till recently. Continue reading ‘Weekend Server Upgrade’ »
This is what I ran into for the first time: I was flashing the chip the other day and after many successful runs I encountered the following infamous avrdude error: Continue reading ‘The Case For Using Parallel Programmer’ »
The Google PAC-MAN logo is actually a live game! Continue reading ‘Google PAC-MAN’ »
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. Continue reading ‘A Parallel Port Stepper Motor Driver With Discrete Components’ »
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’ »
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’ »
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’ »
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’ »