Power supply unit-5 volts from 230 volts

Posted by Srihari Rao On Friday, December 28, 2012 2 comments
Power supply unit plays major role in any circuit. If the circuit is needed to work efficiently then the power supply unit should be made properly. Many electronic circuits are powered by 5 volts supply. So every electronic enthusiast needs to build a 5 volts power supply circuit for all his home projects. This 5 volts supply can be used to power any circuit like microcontrollers etc.

Components needed for this circuit are:

Diodes - 1N4004
C1 - 1000uF
C2 - 0.1uF
C3 - 0.1uF
Regulator - 7805
Indicator - LED
Resistor 330Ω
Step down transformer - 12-0-12

Above circuit shows the Power supply unit. The four diodes perform the rectification and converts ac supply into dc supply. The ac supply is given from step down transformer. C1 capacitor removes the ac supply present. 7805 provides constant 5 volts supply and LED is just used to indicate that is circuit is ON. 
You can make this circuit on a general purpose PCB board and used it to power any circuit. 

Here are the proof of the circuit.

Don't hesitate to comment below if u have any doubts.
Hope this circuit will be helpful for your projects. 


Introduction to HDL

Posted by Srihari Rao On Sunday, December 16, 2012 1 comments
HDL - VHDL and Verilog

There are many programming languages being used today for many purposes. In those HDL is one programming language. Then today let us learn what is this HDL and why it is used.

Introduction to HDL

What is HDL and why HDL?

Hardware Description Language (HDL) is a Computer-Aided Design (CAD) tool for the modern design and synthesis of digital systems. It is used to verify complex designs before they are manufactured by any company. Once the design is made ready it is written in form of code and will test the components connections and behavior. Once it is verified thoroughly then the circuits will be manufactured. They are generally realized by programmable chips like Application-Specific Integrated  Circuits (ASIC) and FPGA's and would require CAD tools. HDL is one such CAD tool.

The designer uses HDL to describe any digital system in a computer language which is similar to high level language such as 'C'. There are two widely used HDL's. They are:

  1. VHDL
  2. Verilog
History of VHDL

VHDL stands for Very High Speed Integrated Circuit (VHSIC) Hardware Description Language. It was developed in early 1980's under the VHSIC program. Many companies were involved in designing VHSIC chips for US Department of Defense  At that time each company used their own HDL which provided them only gate level design tools. So the need for standard HDL was generated.

IBM, Texas Instruments and Intermetrics was given the work of developing a powerful standard HDL based tool by DoD. First publicly available standard was VHDL version 7.2 in 1985. In 1989 this VHDL was made to standardize by IEEE. In 1987 it became IEEE Standard 1076-1987.In 1993 VHDL was updated and more feature were added to it to become IEEE standard 1076-1993. 

History of Verilog

In 1983 Gateway Design Automation developed a hardware description language for its newly introduced logic simulator, Verilog-XL. In 1990 Verilog HDL was available as public domain. In 1995 Verilog HDL became IEEE standard 1364-1995. The language is currently maintained by the Open Verilog International (OVI) organization. Verilog code structure is based on C language. 

That's a brief introduction of HDL. We will be posting more about HDL like some basic programs to verify some digital circuits. In my next post i will be providing software to debug and run and your HDL codes.

Have anything to ask. Just comment below.


Light dimmer circuit using DIAC and TRIAC

Posted by Srihari Rao On Friday, December 14, 2012 14 comments

Light dimmer circuit is using to adjust the illumination of lamp. The below circuit shows the basic TRIAC triggering circuit using DIAC. Here in this circuit the light illumination is controlled using TRIAC and DIAC. 


The resister and capacitor are connected in series. The capacitor is made to charge through the 500K resistor. When the capacitor starts charging and when it reaches above the breakover voltage of DIAC, it starts conducting. Hence capacitor voltage is applied to TRIAC gate and it turns-on. The charging of the capacitor can be controlled by the variable resistor. Which indirectly controls the firing delay of TRIAC.

Light Dimmer Circuit

You can do this circuit and vary the illumination of the bulb. 

Hope you all like this basic light dimmer circuit. Feel free to comment.