Electronic ignorance

Dave,

I really like the graphics - none of the others do that. I also like the simplicity of use - again, the others are much harder to use unless you happen to have experience with them (which is were this subject came in).

Mark

I don't know... but I too have discovered that Vauxhall helpfully use red for earth cables...

Neil

Perhaps the best advice to someone who doesn't want supertechnical is read anything by R. A. Penfold in the Bernard Babini books

Neil

When I was an apprentice I was warned to look out for red earth cables, as a temporary wartime measure red was chosen as earth as all flex cables seemed to have a red. They were still cropping up in 1973 in my second year, it was always a recable job not just a new plug top.

Mike

It's funny but becoming licensed pretty much coincided with the end of my radio activities. Before then, I constructed digitally synthesised signal generator 100kHz - 850MHz; 700MHz DFM, various 2m and HF receivers and transmitters, 1kW linear amp (2m), various modified CB equipment, aerials for 2m and HF and several portable transmitters and receivers. Then I became 17 and things started to happen like cars, bikes, beer, females etc and the radio thing faded away.

My friend at the time was the youngest ever candidate to pass the RSGB exam (G8XLA?) and went on to do the Morse test too. He now has 2 tanks, a real helicopter and all sorts of stuff. I met him when he had been stopped by a copper for riding his home made motor trike on the local bridal path. As I was on my own home-made motor bike at the time, the copper had his hands full. Plod let us both off and Kev and I went to make some interesting stuff over the years ....

I was just up the road from you in Harrogate.

Murray

I spent a bit of time looking around on the web for something really simple. There is Dummies site and I thought that might do - no some mistakes. Some think transistors need the physics of doping in order to get a very basic idea of what they do. After 5 google pages I gave up. It was getting worse rather than better than this one

**LINK**

It's pretty honest in respect to integrated circuits. The data sheets do state what they can do. If it included logic chips separately it might have said that they do things with binary patterns of 0's and 1's. Logic operations of some sort. It could mention a number of specific types but google would come up with a broad definition of any of them - some where and that aspect might be a problem.

He also manages to explain an inductance in a simple way but that wont make much sense until some one realises what capacitors do in different types of uses. Inductors are there opposite and in transformers they sort of serve a different function which in this case also has it's unfortunate aspects.

I did it because I suspect this is the sort of thing that the OP was asking for really ever since I read the post. If at some point he wanted to go further this sort of information would still help. It seems to be rather thin on the ground.

John

-

Edited By Ajohnw on 01/08/2016 20:56:53

Hi,

I am a recently graduated electronic design engineer(2013) and we started with Floyd its straight forward and clear and covers all the basics with lots of diagrams. Electronic Devices 9th Edition - Floyd any addition will do . Get the conventional current version if possible I got mine second hand at better world books for £15.

Regards

Mark

Quite so, in signal processing theory the related Kronecker delta is rather more useful. It is simple to create a comb function using repetitive Kronecker deltas and from that one can construct discrete time sampling theorems and derive the relationship between sampling rate and bandwidth. The same concept can also be used to derive the impulse response of filters, which tells you how they will be behave for different frequencies. If one can't be bothered to do the maths the concepts can be visualised graphically.

Andrew

They both crop up in a number of areas Andrew, especially the pulse

One for Neil

**LINK**

John

-

Andrew, some of my radio gear has different filters available. Whilst being 'different', the actual sound and filtering effect are very similar. In an undemanding condition, perhaps so. Maybe not something we actual mortals need worry about overmuch. I built a Comb Generator, and wrote it up for PW. It used the propagation delay between gates of an IC to generate a signal going into the UHF region with a 10 MHz cheap crystal,

Geoff

Sorry Mr. bandersnatch, wrong poster, can't remember more than a day. Still red negative tho'.

There are some open source packages about. Circuit seems to be one but the use of it I posted doesn't show the real waveforms that would come out of it.

There is a design for an RF oscillator from Wireless World about on the web. The construction method shown is interesting - built on a pcb it probably wouldn't work very well at all.

There are still a number of designs from that magazine about. They are generally rock solid designs. Pity all of them aren't about. The magazine changed more or less over night when an American company bought it out. This infuriated a lot of people as the magazine was a very useful educational source for a lot of people who could manage the basics. It also provided designs for a lot of very good quality test gear that could be built very cheaply compared with commercial equivalents.

John

-

I gave up on Practical Wireless in the early 1980s when i started getting Model Engineer, still got a box full of PWs, and the name Geoff Theasby sparked some memories.

Ian S C

Geoff: I guess it depends what sort of filters. Traditional analogue filters were designed on the complex s-plane using poles and zeros. To save a lot of mathematics standard filter characteristics are tabulated. There used to be huge books of tables and component values available which could be modified according to the frequencies involved. The three most common types of filter were:

Butterworth - poles only on a circle on the s-plane - flat inband amplitude response and a reasonble rolloff

Chebyshev - poles only on an ellipse on the s-plane - trades inband amplitude ripple for a steeper rolloff

Elliptic - adds zeros to a Chebyshev filter - creates ripple in the stopband as well as passband, but even steeper rolloff

Passive filters used inductors and capacitors, but active analogue filters use opamps, capacitors and resistors. The classic active filter uses the Sallen-Key topology, although for practical designs it can require wide variations in component values which may not be practical.

Digital filters are different. Finite impulse response filters (FIR) are designed using the required impulse response. An FIR filter is simply the weighted summation of a number of previous signal samples, ie, convolution. They are uncondtionally stable and, unlike many analogue filters, can be designed to have a linear phase response, ie, no signal distortion. An alternative is the infinite impulse response filter (IIR) which involves feedback. An IIR filter is computational efficient, but due to the feedback can suffer from limit cycle oscillations, where the output oscillates even with zero input usually due to rounding errors. With the advent of floating point on even cheap microprocessors this is now less of a problem.

Of course if one wants an low frequency filter these days you just reach for a switched capacitor filter. Everything you need in one IC, just add a clock.

Andrew

Andrew, indeed. Part of the problem with practical analogue filters for amateur purposes is finding or creating a design which could be built with easily available components, esp. capacitors. As you say, digital filters are, by contrast, extremely good and unbelievably effective.

Ian, Yep, the very same! Twice as old now and twice as ugly, but no wiser (See current Club News)

Geoff

Andrew, indeed. Part of the problem with practical analogue filters for amateur purposes is finding or creating a design which could be built with easily available components, esp. capacitors. As you say, digital filters are, by contrast, extremely good and unbelievably effective.

Ian, Yep, the very same! Twice as old now and twice as ugly, but no wiser (See current Club News)

Geoff

I'm a sucker for second-hand books. Last night I dipped into a recent purchase ("Morton's Advanced Electrical Engineering", to find this comforting start in the Preface:

Lewis Carroll, the genius of gentle humour, writes in The Three Voices,

Or, stretched beside some babbling brook,
To con, with inexpressive look,
An unintelligible book.

While it is not anticipated that this present volume will be read in such pastoral surroundings, it is hoped that it will not prove unintelligible to those for whom it is intended.

Unfortunately after luring me into a false sense of confidence, the first paragraph of Chapter One assumes that I already know what a linear circuit and a passive element is, the difference between current and potential difference, the meaning of impedance and admittance, and that I understand that a source of electrical energy might be constant-voltage or constant-current. Good mathematical skills are needed too - Chapter One then plunges straight into "simple" Matrix Algebra.

This is not a good book for a beginner, and it reminded me of Rod's original question "Seems I need an idiots guide to basic electronics. - Is there such a thing? Could anyone offer constructive advice as to how I might move forward"

Most of the "good" books I used in my youth are out-of-date. They all spend a lot of time on thermionic valves and are blissfully ignorant of the 40 years worth of rapid development since they were written.

If I were starting today, I would buy a copy of "The Art of Electronics" by Paul Horowitz and Winfield Hill" as recommended by Andy Ash in his first reply. The book is up-to-date, it doesn't assume much too much of the reader, it summarises most of modern electronics and, in the opinion of many, it's well written.

I wouldn't rely only on the book though. As others have pointed out H&H isn't aimed at complete beginners. I'd use the web to supplement and clarify the book. Steve Withnell provided this excellent **LINK** to a simulator containing animated examples of many circuits. I wish such a thing had been available when I were a lad. The simulator also allows you to enter and test your own circuit diagrams, so you can use it to double-check your understanding. If that's not enough, Google is your friend, as is this forum.

Be aware though that learning electronics takes effort - it's not something you can do over a weekend. It's a bit like learning to ride a bike: you have to get your head round some new concepts and language before it starts to make sense.

Dave

Edited By SillyOldDuffer on 05/08/2016 11:47:42

Dave,

"Be aware though that learning electronics takes effort - it's not something you can do over a weekend. It's a bit like learning to ride a bike" or beating a set of drums (learning percussion) - which I thought would be easy for someone used to hitting stuff.....

Mark

Hi Dave,

If i may, I think some people have good ideas but aren't very good at getting them across to other people. I'm probably more the other way and don't have good ideas often, but am very good at making things seem as plain as day and can spot a book a mile off if it's going on a tangent.

i actually don't like reading books in general, and authors' who wrongly assume you know what they know.

I'm not a book seller and definitely not the most informed on whats out there, but i wanted some help on getting some background reading on electronics and my tutor recommended this;**LINK**. Success in Electronics by Tom Duncan, theres a plethora of good reviews on amazon for evidence but i shan't go into that.

It basically assumes you only have ever just used electronics and don't understand them, consumer products for example, it starts right at the beginning, explaining what a linear circuit is and basic electricity in part one.

I implore you to consider my opinion as it seems to be quite popular with alot of other beginners too.

Michael W

The older books sometimes use rather outdated language, but the fundamentals don't change. A modern current source (I've just designed one using the LT3902) is fundamentally the same as it was 40 years ago. It's just the implementation that has changed. One needs to distinguish between understanding the fundamentals and knowledge of current electronics. They're not the same thing. In my experience really good engineers understand both.

I've been faffing around with electronics for 40+ years and I'm still learning.

Andrew