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22 Jul 2012

## Switch Basics

Learn the basics of switches on this PDF

19 Jun 2012

## MITx / edX 6.002x Circuits and Electronics Course Review

Gil Junqueira write:

It has been 6 weeks since I last reviewed this course. At that time, I was just about to take the mid-term exam. Now it is 6 weeks later — and 14 weeks since the beginning of the class. I finally received  my certificate of completion.…

I have to say that these 14 weeks were somewhat painful, as the necessary study required to complete homework in time and keep up with class materials were in direct conflict with my work schedule and ability to spend time with family. This wasn’t without warning, as MIT personnel did indicate that  8 to 10 hours of study time per week would be required in order to keep up with the course.

But at the end, despite all the hours spent on the computer cranking out code to solve problems late at night, (I gave up on doing the math by hand after week  and so should you if you take this course in the future) I would do it all over again. This was by far one of the best electronics courses I have taken anywhere. While the material was not completely new to me (I took electronics courses before), the way it was presented was…

MITx / edX 6.002x Circuits and Electronics Course Review – [Link]

19 Jun 2012

## Estimating the Cooling Requirements of an Electronic System

Any electronic system generates waste heat during normal operation. This heat must be removed – otherwise, it might damage the system components and cause malfunctions. Whether you are designing a system or diagnosing a system’s cooling requirements, you need to know which parameters to look at and how to estimate the airflow that will maintain a safe temperature within the system.

In a typical cabinet-mounted system, there are usually one or two power supplies, electronic circuits and displays, all of which can be assumed to generate heat within the cabinet. From the system’s power requirements, a fair idea of the power input may be estimated. If the system is cooled by simple convection, the thermal capacity of air can be taken to be 0.569W-minute/°C/ft³.

That means, every cubic foot of moving air can remove 0.569 W of dissipated heat every minute when its temperature changes by 1°C. To express it reciprocally, to dissipate 1W of heat, and maintain a 1°C change in temperature, an air stream of 1.757cfm (1.757 cubic feet per minute) will be required. Therefore, once you have estimated the heat dissipation within the system, estimating a cooling fan’s rating in cfm will depend on the internal temperature rise you allow. However, until you have completed your measurements and fitted the right size of fan, there will always be the risk of failure of system components. Therefore, for experimentation, what you need is a representative model.

11 Jun 2012

## Free ebook – Starting with the electronics hobby

Book #1 : Starting with the electronics hobby – Free to download

Other 4 ebooks are available to purchase. John @ www.theelectronicsbook.com writes:

This book will teach you all the basic rules of the electric circuits world. It will guide you step by step with pictures and examples. More than 80 pages of theoretical and practical information.

This book includes the following subjects: Electric current, voltage, Resistance, Water-electronics analogy, Ohm’s law, Waveforms, What is a multi-meter?, Using multi-meter, Component’s part number, Symbols of components , Searching methods for components, datasheets, Resistance color code, Circuits with resistors , Experiment: Resistance measurement and many more basic rules of the electronic circuit.

No previous knowledge is required. Starting from the basics and moving on to practical electronics. Many examples and experiments on every electronic component. Full of pictures for better understanding.

Free ebook – Starting with the electronics hobby – [Link]

1 Jun 2012

## 5 Tips for Using a Multimeter for Your Home Improvement Projects

If you are someone who enjoys doing your own home improvement and you are working with electronics during the process, having access to a multimeter is an absolute must. There are going to be instances where you will need to be able to measure voltage, ohms and continuity and without an electronic multimeter, it will be difficult to determine just what you need to do. Here are a few tips for using your multimeter to perform home improvement projects.

1. Understand your options – Multimeters are available in different types. These can run from the most basic to the most luxuries, which is also the most expensive. Unless you have highly advanced electronic skills and knowledge, a basic multimeter is going to be just fine and will have fewer features that you need to figure out.
2. Familiarize yourself with your multimeter – Take some time to examine the multimeter before you use it. When looking at the face of the design you should see three different things – dial, settings and lead ports. These should be color coded which makes it much easier to avoid mistakes when plugging in leads.
3. Learn the dial settings – As you look at the dial, take notice of the symbols and numbers that surround it. You should see an arrow that points to the right with a plus sign beside it. This is the setting that is used for continuity. The “V” setting is used for voltage and the setting for ohms or resistance will look like a “0” with feet.
4. Learn the uses of your multimeter – You can test a random electrical outlet to make sure that the multimeter is working properly. Use the “V” setting for this. Check to ensure that power is not flowing through any electronic circuits that you are testing. If you would like to test for a blown fuse, remove the fuse from the clamps and set the meter for continuity testing. Simply touch each end of the fuse with the meter’s probe and if the fuse is operating properly you should hear a beep.
5. Test for amperage – When testing for amperage you have to be a bit more careful. This is a more complicated process and requires that you use more than just two probes. You can use a clamp add-on for amperage testing by plugging it into two ports that read “A” and “Com.” Clamp the tester onto the hot wire that you want to test or you can simply purchase a plug that includes a wire loop specifically designed to test amperage.

This article was written by Electric Point, one of the largest independent wholesale groups in the UK and Ireland. Visit us today at electricpoint.com

1 Jun 2012

## P-FET Reverse voltage polarity protection tutorial

Rectifier circuit with very low voltage drop featuring a P-channel MOSFET  – [via]

Different ways you can protect your circuit from backwards power connections. Diodes, schottky diodes and P channel MOSFETs.

P-FET Reverse voltage polarity protection tutorial – [Link]

24 May 2012

## Diode Tutorial & How to build an AC to DC power supply

This video covers the basics of diodes, bridge rectifiers, and how to build simple unregulated AC to DC power supplies than can handle a few mA up to several Amps. Diode Tutorial & How to build an AC to DC power supply – [Link]

9 May 2012

## Understanding power MOSFET data sheet parameters

Having a hard time trying to figure out whether that FET can handle enough current for your project? AN11158 from NXP might help clarify some of the many parameters that you need to take into account that are often overlooked.  The Safe operating area, for example, is an important one that often gets skipped and people just look at the best-case scenario marketing numbers on the front page of the datasheet: “The Safe Operating Area (SOA) curves are some of the most important on the data sheet. The SOA curves show the voltage allowed, the current and time envelope of operation for the MOSFET. These values are for an initial Tmb of 25°C and a single current pulse. This is a complex subject which is further discussed in the appendix (Section 3.1).”

Understanding power MOSFET data sheet parameters – [Link]

16 Mar 2012

## TI – Op Amp Circuit Collection

The National Semiconductors that now belongs to Texas Instruments in 2002 brought together a large collection of circuits using operational amplifiers, are 33 pages of practical circuits with op amps, with formulas for calculations, and can adapt to your design with operational amplifiers. All together in Application Note 31 of the National Semiconductors.

Op Amp Circuit Collection – [Link]

14 Mar 2012

## Texas Instrument – Op Amps For Everyone

Everyone interested in analog electronics should find some value in this book, and an effort has been made to make the material understandable to the relative novice while not too boring for the practicing engineer. Special effort has been taken to ensure that each chapter can stand alone for the reader with the proper background. Of course, this causes redundancy that some people might find boring, but it’s worth the price to enable the satisfaction of a diversified audience.

Texas Instrument – Op Amps For Everyone – [Link]