Tuesday, May 31, 2016

A Brief History of C Programming

· General-purpose language which has been closely associated with the UNIX operating system for which it was developed - since the system and most of the programs that run it are written in C.
·    Many of the important ideas of C stem from the language BCPL, developed by Martin Richards.
·      In 1972 Dennis Ritchie at Bell Labs writes C and in 1978 the publication of The C Programming Language by Kernighan & Ritchie caused a revolution in the computing world.
·        In 1983, the American National Standards Institute (ANSI) established a committee to provide a modern, comprehensive definition of C. The resulting definition, the ANSI standard, or "ANSI C", was completed late 1988.

Wednesday, May 25, 2016

Automatic Temperature Controlled Fan


So, I just wanted to randomly post about a simple Engineering project that can be done as a minor project during your electronics engineering degree. The project is not much hard and can be easily done. The basic circuit diagram of the project is:
Circuit Diagram (Proteus Simulation of the Project) 

The basic working principle of the fan is that, when the temperature increases the fan starts rotating. We have kept a DC motor in place of fan in the above proteus simulation of the project.
The circuit exploits the property of Thermistor to operate the DC Fan. Thermistor is a kind of temperature dependent resistor and its resistance varies depending on the temperature in its vicinity. There are two types of Thermistors- NTC and PTC.
Negative temperature coefficient (NTC) Thermistor decreases its resistance when the temperature increases while Positive temperature coefficient (PTC) increases its resistance when the temperature increases. Thermistors are bead like resistors available from 100 ohms to 10K or more values. Here a 4.7K NTC Thermistor is used. IC 741 is used as a voltage comparator to switch on the DC fan. Its INV input (pin2) gets an adjustable voltage through VR while its Non-INV (pin3) input gets voltage through a potential divider comprising R1 and the Thermistor. Thus the voltage at pin3 depends on the conductivity of the thermistor.
When the temperature is normal (as set by VR), pin3 gets higher voltage than pin2 and makes the output of IC high. This high output keeps T1 off since its base is positive. DC fan remains off in this condition. When the temperature increases above the value set by VR, resistance of Thermistor decreases and the voltage at pin3 decreases. As a result, output of IC becomes low to switch on T1.
A small brush less DC fan (one used in computers) turns on to increase the air circulation. When the temperature returns normal, Fan automatically turns off. Diode 1N4007 is necessary to remove back EMF when T1 turns off.



(If you need further help about this comment below.)

About C Programming

I will be posting about C programming from basics including example programs and solutions. If you need any help regarding any programs and problems related to C, you can post in comments below, and I will try to help you as soon as possible. Thank you