NDIR Based Co2 Meter

The next review is about a home-built Co2 meter, which is built on the concept of NDIR. NDIR stands for non-dispersive infrared sensor which is a simple spectroscopic device often used as gas detector. It is called non-dispersive because wavelength which passes through the sampling chamber is not pre-filtered instead a filter is used before the detector. We already have NDIR based gas-modules which are a common type, small size sensor, using non-dispersive infrared (NDIR) principle to detect the existence of CO2 in the air, with good selectivity, non-oxygen dependent and long life. The sensor used is a MH-Z14 IR module which outputs a PWM wave based on the level of gas detected. It has a sensitivity of 0 to 2000ppm Co2. For those who are interested in the project … Continue reading

ATmega88 based POV weather station generates its own power

We like POV(Persistence of Vision) projects – specially those with unique ways to transmit energy to the turning row of LEDs (Light Emitting Diodes). This POV however beats the rest that we have seen so far – this one is a freakin weather station. Instead of displaying graphics this POV displays the current temperature and relative humidity. And the best thing we like about this guy? It generates its own energy! It uses a stepper motor as a generator, when a stepper motor is turned current flow through its wires. It is then rectified using a set of diodes and stored into a 6 – capacitor charge bank. The Charged stored in the bank is then fed to a  TPS5420 buck converter that outputs 3.5V – just enough to drive the … Continue reading

A microcontroller based DDS function generator using an AD9833

A DDS Function Generator

First what do we mean by DDS – DDS stands for direct digital synthesis. A DDS chip generates a waveform from an internal ROM with table. The ROM table could contain square, triangular, sawtooth or sine wave forms. A high frequency oscillator is used to drive a DDS chip – the high frequency clock is taken into a large internal divider that in turn would generate clock signals of less than 1Hz. The derived low frequency signal will be used to tell the on-chip digital to analog converter to go to the next value on the ROM table. This particular project makes use of the AD9833 DDS sinewave generator from analog devices. A 50MHz clock was used to drive the AD9833 while an ATmega32 was used as the main controller … Continue reading

A microcontroller based automobile digital RPM meter

Some of the smaller cars available today does not have an RPM meter on them – this would be some trouble since you wont be able to determine the actual speed of the car’s engine, thus will have an impact on the fuel consumption since engines are efficient at a certain range of shaft speed. This project makes use of an AVR microcontroller and a signal conditioning circuit that makes use of an LM324 operational amplifier (Op-Amp). The input signal was taken from the High Voltage (HV line) of the main distributor of the engine. This specific point was chosen since all (gasoline) engines have an HV line. The signal from the HV line is fed into the signal conditioning circuit before being fed to the microcontroller’s PB1 pin. The Timer/Counter1 … Continue reading

Kick start guide for developing and debugging in AVRStudio5

Most of hobbyists like AVRStudio4 and still tries to avoid AVRStudio5 which is heavier in size and still may have some unconvenient bugs. But in general this is great tool with much better editor. If you still hesitate about choosing AVRStudio5, take a look at Pete’s tutorial where he displays how to set up Atmega1284P project. Probably major disappointment with AVRStudio5 is that it discontinued support of old debuggers like JTAG ICE where you could build clones. If you want to debug your projects you will need a debugger. Pete suggests JTAGICE Mk3. Original one is quite expensive ($300). So Pete gives some tips on how to find decent clone which costs around $80.