Archive for 2010

Modified Sine Wave Generation With AVR

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’ »

Simple External Powered USB Port

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’ »

4KHz-170MHz Wide Band RF Signal Generator – II

Continue with my previous article, let me first explain the code a little bit. Continue reading ‘4KHz-170MHz Wide Band RF Signal Generator – II’ »

4KHz-170MHz Wide Band RF Signal Generator – I

A signal generator can come in handy when working with digital and analog circuits. While most commercial grade signal generators offer more than just outputting a sinusoidal waveform, they are quite pricey for casual use. In this article, I will show you a simple wide band signal generator that is built around a Linear Technology’s LTC6905 Silicon Oscillator, which is can generate frequencies from roughly 17MHz to 170MHz. Along with a FairChild Semiconductor’s 74VHC4040 12-stage high speed binary counter, this signal generator is capable of generating precise frequencies from as low as 4KHz all the way through the ranges of LTC6905. Continue reading ‘4KHz-170MHz Wide Band RF Signal Generator – I’ »

Brother MFC-7340 Setup Under Linux

I just bought a Brother MFC-7340 multifunction laser printer to replace my old Lexmark Optra E310 which I have had for about ten years. Lexmark Optra E310 has excellent Linux support and I have been using CUPS to make it a networked printer. So naturally, I wanted to setup the new printer the same way. Continue reading ‘Brother MFC-7340 Setup Under Linux’ »

Temperature/Humidity Data Logger — Trial Run

I built a rather generic I2C data logger a few weeks back. As I mentioned in my earlier posts, it can be used to log data from almost any I2C slave devices with relatively little code modification. Continue reading ‘Temperature/Humidity Data Logger — Trial Run’ »

Hex/Bin/Dec Converter And Calculator

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’ »

Wide-band RF Field Strength Meter

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’ »

RF Data Link Using Si4021 And Si4311

Among the many commercial ISM band RF transmitter and receiver ICs, I have found that Silicon LabsSi4021 (transmitter IC) and Si4311 (receiver IC) are surprisingly easy to work with. Only a few commonly available external components are needed to build a fully functional circuit. The integrated automatic antenna tunning circuit in Si4021 makes building transmitters an easy task. The Si4311 receiver IC is highly integrated, more so than many other ISM band RF ICs, and is quite tolerate to the variance of the required few external capacitors. No special tuning is required. Continue reading ‘RF Data Link Using Si4021 And Si4311’ »

AVR LC Meter With Frequency Measurement

I have been thinking about building an LC meter for a while since I do not have a multimeter that is capable of measuring inductance and while the multimeters I have can measure capacitance, they are not able to give accurate readings for small capacitance in the range of several pF’s. Continue reading ‘AVR LC Meter With Frequency Measurement’ »

My New DS1052E Oscilloscope

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’ »

I2C Data Logger Using ATmega328p and DS3232 – II

In my last blog post, I showed you the schematic of a I2C data logger I built. Here I will discuss some sample code used for this data logger and how to make it even more flexible. Continue reading ‘I2C Data Logger Using ATmega328p and DS3232 – II’ »

I2C Data Logger Using ATmega328p and DS3232 – I

There is a popular data logger shield out there designed for Arduino using a DS1307 real time clock chip. And that design makes data logging extremely easy if an Arduino board is used. Continue reading ‘I2C Data Logger Using ATmega328p and DS3232 – I’ »

ZIF Arduino Prototyping Board

The official Arduino Duemilanove board is an excellent tool for prototyping. For most of the users, it is a very solid platform for various MCU experiment circuits given the number of readily-made shields available. Continue reading ‘ZIF Arduino Prototyping Board’ »

A High Current TRIAC Controller Using Arduino

One of the goals in my previous timer project was to achieve the ability to control multiple electronic devices using the precise time signal generated by the RTC chip (bq3287). For electronic devices using up to a couple of amperes, a relay should be more than capable to handle the load. But for high voltage and high current home appliances such as water heaters (typically 240V, 20 to 30 A), the relay solution becomes much more expensive and less reliable. Continue reading ‘A High Current TRIAC Controller Using Arduino’ »