Circuit Negma

C++, C, VB.NET, PCB, Electronics, Circuit Design

Archive for March, 2008

Switching-Mode Power Supply Design Tutorial

Posted by Circuit Negma on March 19, 2008

A switching-mode power supply is a power supply that provides the power supply function through low loss components such as capacitors, inductors, and transformers — and the use of switches that are in one of two states, on or off. The advantage is that the switch dissipates very little power in either of these two states and power conversion can be accomplished with minimal power loss, which equates to high efficiency. The term switchmode was widely used for this type of power supply until Motorola, Inc., who used the trademark SWITCHMODE TM for products aimed at the switching-mode power supply market, started to enforce their trademark. Then more generic terms had to be found. I started using the term switching-mode power supply to avoid infringing on the trademark. Others used the term switching power supply, which seems to be the more popular term. PSMA does not define either switching-mode power supply or switching power supply, but does define switching regulator.

Switching-mode power supply design tutorial by Jerrold Foutz


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RJ45 Jack with Magnetic coupling

Posted by Circuit Negma on March 14, 2008

The above picture is the internal schematic representation of part number J0011D21B RJ45 jack from Pulse Inc. @

I have came across this component during me design stage of Ethernet controller.

Unfortunately, my schematic software (PADS LOGIC) did not have such a component in its library; so I had to build the above component from scratch.

I used AutoCAD to build the above component and I save it as AutoCAD 12 DXF file.

I followed the following steps to import AutoCAD DXF file into PADS library.


2. File > Import > browse to the above DXF file.

3. Once PADS has imported the file, highlight (select everything) the above component.

4. Right click on the selected component > combine

5. Right Click on the selected component > Add to library

6. Give this new shape (component) a name.


And you are done.


2. Tools > Part Editor

3. Click on Edit graphics in the Part Editor Toolbar

4. Click OK to the message

5. Hit the Page Down button a few times to zoom out the screen

6. Click on Add 2D line from Library from in the Symbol editor Toolbar

7. Locate the above drawing and click OK to add it to the screen.

Now, you just have to either add pins or create some kind of shape around the above drawing to create your own custom component.

Note :: To obtain the DXF file, click on the above image and save the file to your harddisk. Then use WinZIP or winrar to extract the DXF file from the image. To do so:

1. open winzip

2. File > open

3. browse to the save image file


1. Open WinZip

2. Drag the image and drop it off inside the WinZip software.

Posted in AutoCad 2006, Electronics | Tagged: , , , , , , , , , | 2 Comments »

MatLab DC/DC Design

Posted by Circuit Negma on March 13, 2008

Robust controller design using multi-objective optimization
The powerful SQP algorithm such as implemented in MATLAB will speed your DC/DC designs

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Basic Electronic Components

Posted by Circuit Negma on March 10, 2008


All components used in electronic circuits have three basic properties, known as resistance, capacitance, and inductance. In most cases, however, one of these properties will be far more prevalent than the other two. Therefore we can treat components as having only one of these three properties and exhibiting the appropriate behavior according to the following definitions:


    The property of a component to oppose the flow of electrical current through itself.


    The property of a component to oppose any change in voltage across its terminals, by storing and releasing energy in an internal electric field.


    The property of a component to oppose any change in current through itself, by storing and releasing energy in a magnetic field surrounding itself.

As you might expect, components whose main property is resistance are called resistors; those that exhibit capacitance are called capacitors, and the ones that primarily have inductance are called inductors.

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