Science on the Web – Part Two, Tomi Engdahl

Science on the Web – Tomi Engdahl

Continuing in our weekly series of Science on the Web, this week’s honours go to Tomi Engdahl.

One thing that should never surprise one is the tendency of great web masters (like previous article on Rod Elliott) to keep it straight and simple.  I have been reading Tomi Engdahl’s articles for more than ten years now – he now owns and authors the website ePanorama.net and the mostly technological driven articles are directed at audio, RF, wiring, circuits to amateur radio.  ePanorama also hosts a blog page.  What makes his website so fascinating?

Education and Passion

Many years ago a friend of mine said to a circle of friends that to him electronics is not a hobby, it’s a profession. I strongly disagree. The people I have learnt the most from are absolutely passionate about their hobby which may just have been electronics. They do not see it as a profession. My wife lectures subjects in horticulture at a local university of technology. She breathes, eats and thinks plants – every day. This is a passion. She brings her work home. There is always something exciting happening out in the garden.

People only interested in electronics as a job, a means to an end, I doubt learn much from experimentation which leads me to surmise that what they know comes from books and quick fixes. ePanorama covers all facets of electronic engineering – anyone learning about transistors, resistors, capacitors and bias points will not stop only at audio amplifiers, radio and power supplies. It is inherent in them to learn how all stuff works and to fix stuff.  So you have a computer – you can write in Word, do calculations in Excel and make a simple database in Access. You can draw, paint and record videos. The electronics guy will make his computer do more than that. They will learn about how the computer communicates through the serial, parallel and USB ports. They will learn how to program. They will make the computer do things. When you speak to them they will tell you what they made, how it worked and what problems they had. That is passion. That is a hobby. The electronic hobbyist is interested in technology. Most people in the electronics industry seem to stick to only one sector in their professional lives but diverse after hours.

Tomi and Tom – Science on the Web

Tomi Engdahl brings his passion to the pages of ePanorama. There are loads of links to technical articles much of which has been written by Mr. Engdahl. Lots of links to RepairFAQ (we cover this in another article on Science on the Web). In essence, we move from the basics to beyond. I am not a big lover of articles written on computers for and about computers, especially gaming machines, only because they become dated too quickly, the life cycle is over in a  few months – however the topics in ePanorama are relevant to the technical minded.  Like Tom’s Hardware may be for the computer geek, ePanorama is for the electronics geek.

Amateur Radio

Having studied marine telecommunications years back I often wonder whether amateur radio has lost a lot of appeal in our computer and satellite communications age.  Amateur Radio, I think, is an oft misunderstood term – lay people see it as a hobby for people interested in telecommunications.  This is indeed not the case – many amateur radio hams are highly qualified or knowledgeable people, guys or girls. Much of our modern day telecommunication technology we owe to the hams of yesteryear. For more information go the ePanorama links page for the American Amateur Radio RelayLeague (ARRL).

Class A, AB and D Audio

A fairly comprehensive page with links on Class D design in audio can be found here. Although Class D is not something most of us will want to delve into, circuit board design is critical, interference can have the authorities tapping on your door in a flash it nonetheless does interest most designers of audio equipment. Modern designs using ICs are also covered.

While there is a host of amplifier circuits incorporating AB class design and a few with class A note that much of this is only in the form of a schematic. Stick to websites with a good explanation before embarking on a 1600W audio amplifier without a very good knowledge of how it works, how much it will cost to fix when it blows and of course worse still burns out your expensive speakers.

Many of the amplifier circuits for standard class AB are fro very old designs but tried and trusted. Nice and cheap stuff to build with components from the junk heap.

Digital Signal Processors

One of the trends in most audio circuit designs now is around home theater. The problem with this always come down to the digital signal processing stage – it is out of the design and possibly scope of most DIYers although sadly it should not be.  Home theater amplifiers do not reproduce vinyl, CD or DVD sound as well as the old stereo amplifiers – they are designed strictly around generating that home theater sound – high bursts of power at short intervals. Try playing a concert at the rated output for long periods of time or using your home theater amplifier for a party you will no doubt find the amplifier will overload or self destruct after an hour or two. The mains transformers are particularly prone to failure or temperature shut down – most often the power transformer is designed to hopefully drive only two channels simultaneously. The home theater user often parallels his loudspeakers to get more power or drives the amplifiers into a 4 Ohm load, something which many of them are not designed to do for continuous power reproduction.

To keep prices down the transformer and power supply is often a watered down version of the real thing – transformers are notably very expensive. Tomi Engdahl’s ePanorama pages do cover DSP quite comprehensively – although it has it’s own page and is indexed there is a lot of great reading material through the site search.

Computers

As mentioned previously, as wonderful as your home PC or laptop is most people are not aware that they are only using a fraction of the actual power that can be delivered. Video rendering and games are two great and the computer has to work hard, running a word processor program not so.  In fact using basic tools the manual typewriter is just as efficient as a Microsoft Word if used by the layman. In the hands of a professional however, this is a very, very powerful tool. Looking at this scenario it is no wonder that electronics enthusiasts the world over make the computer work for them – usually through the  communications port, nowadays through USB.  ePanorama’s look into the communications and gaming ports may be a bit dated but to get to the end result one needs to look at all the port designs through the years.

To sum up…

ePanorama is aimed at people with a passion for electronics of all ages. It’s a great learning platform and what I like most about the information provided is that it is not just modern electronics – circuit design covers easily the last four decades.  From basic land based telecommunications to mobile communications, from audio class A to D, from serial port communication to sophisticated computer programs this website has it all. What’s more, like Rod Elliott’s Sound Products the navigation is simple. Another real gem of a website.