Electronic ignorance

[Gordon WParticipant @gordonw]

Bandersnatch- re -red neg. cable- van is corsa, about 10 yrs. old, so modern. Wiring and battery are original. I only found out 'cos I'd flattened the battery and wanted to check the voltage after charging. Battery still good, so not bad for 10 yrs. My fault really, when I took off the plastic cover it was clear that both cables were red and clearly marked + & –. Lesson learnt.

[AjohnwParticipant @ajohnw51620]

Posted by Mark C on 31/07/2016 23:29:18:

Rather than assume (always a risky choice), why not try looking, then you would know how they compare….. it should take about the same time as it takes to type a response on here.

It is nothing like conventional simulators and at the same time very similar in operation, the graphical presentation is unique I think?

Mark

It's a windows package and while it part works on Linux and looks much like the version i have used I can't actually use it. It's very similar to the web based one you mentioned ie this one

**LINK**

That shows something I did with it out of curiosity. There are links that can lead to a stand alone java version of it about on the site as well.

The main difference between that and EWB is it doesn't use models of actual parts. In other words rather than just pick transistor pick the type eg BC108 or etc.

John

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Edited By Ajohnw on 01/08/2016 10:55:07

[MuzzerParticipant @muzzer]

My favourite circuit simulation s/w is SIMetrix / SIMPLIS. It's actually British and has been around for a few years now. The free version supports up to 140 nodes which is pretty useful. There are quite a few compts in the std library including controllers, opamps, FETs etc. There are tutorials, videos etc on the website to get you going as well as plenty of examples that you can simply run and play with, some of them pretty complex.

There is also LTSpice which is used by many professionals. Amongst its advantages are the fact it is free but also it supports models of industry standard components such as active devices, ICs (such as PSU controllers and opamps) etc. Obviously it helps LT to sell their components but it's not restricted to just their products. Although it's based on SPICE, it's got a modern graphical GUI and is fairly simple to use. It's also a simple means of drawing up a schematic if you want to sketch out a circuit to illustrate a concept.

Murray

Yes, Practical Wireless used to publish some really excellent articles(!)

Edited By Muzzer on 01/08/2016 11:28:38

[John HaineParticipant @johnhaine32865]

Rod, I'm not sure all this is helping you much. I suppose the question is, what do you want to achieve? Do you want to be able to design your own electronic circuits at component level, or to be able to wire up ready-built modules and troubleshoot common problems with them? If the former, you could try H&H, but if the latter you would just find it baffling and probably unhelpful.

To illustrate what I mean, I've been in electronics all my life and designed things for a living so wouldn't have any fears about designing most things, but in the past couple of years I've built the control electronics for 2 CNC machines and a dividing head, in all 3 cases buying things like stepper drivers, breakout boards, power supplies and so on. There has been little electronics design as such in any of them (but I guess the experience of 50 years counted when a few problems emerged that needed debugging).

So if you're building the electronics for CNC tools or 3D printers you need to know about how the off the shelf modules work as black boxes but you don't need to know much about what goes on inside or how to design them.

[ZebethyalParticipant @zebethyal]

I would say to the OP, how far do you want/need to go with understanding electronics?

You mention struggling to commission a 3D printer – depending on what set of electronics you used, this can be anything from a set of modules (Arduino Mega, RAMPS shield, StepStick/Pololu stepper drivers), an all in one board (Azteeg or Beagle Bone) or a solder it yourself controller, again with StepStick/Pololu drivers (Sanguinololu, etc). whichever route you take, they mainly achieve the same thing – they provide a microcontroller platform on which to run some firmware (Sprinter, Repetier, etc) which in turn needs a few dozen parameters setting in order that it works correctly with your printer and steppers.

All that is in addition to configuring the mechanical printer for squareness, minimal backlash, an accurate origin and being able to traverse your bed accurately such that the nozzle is the same distance above it at all points in a given horizontal plane.

There is very little electronics knowledge required – from the moment you have plugged all of the modules together and wired up the motors and power supply, the electronics side is done and dusted.

Some understanding is required with regards what each of the firmware parameters do (even if you use a known checklist and only ever set them once) and how to upload that firmware, and then some trial and error with regards understanding what difference the various printer settings can have before you find some that are optimal for your printer.

Just trying to clarify what the OP is actually after and whether or not they really need to understand electronics, transistors, op-amps, etc, etc, for what they are trying to achieve, or if they were simply a little overwhelmed by whole end to end process of commissioning the 3D printer, most of which actually has very little to do with electronics itself.

If the wish is to move onto making other projects from scratch, then there is a wealth of information provided by others above in this thread.

[Geoff TheasbyParticipant @geofftheasby]

John, I never heard of a Dirac pulse before, although I knew who he was. Now, having read it up on Wikipedia, my head is spinning, but a picture is worth a thousand words. Just as my Geometry teacher said, "a line has length but no thickness," a Dirac pulse is one occupying zero time with a 100% energy content. Simples! Real life is not so simple though. Gosh, the things I learn in Model Engineering!

[Enough!Participant @enough]

Posted by Gordon W on 01/08/2016 10:36:04:

Bandersnatch- re -red neg. cable- van is corsa, about 10 yrs. old, so modern. Wiring and battery are original. I only found out 'cos I'd flattened the battery and wanted to check the voltage after charging. Battery still good, so not bad for 10 yrs. My fault really, when I took off the plastic cover it was clear that both cables were red and clearly marked + & –. Lesson learnt.

Sorry Gordon, you lost me. Are you sure you replied to the right person/thread?

[Enough!Participant @enough]

Posted by Geoff Theasby on 01/08/2016 05:24:47:

Bandersnatch, I have a small collection of books of this nature. Inc. one on how wonderful the new material called 'Radium' is! One on photography from the late 1890s, how to make your own 'Televisor' etc.

Ooh …. jogged a memory there, Geoff. I used to have an old book with an article about constructing a flying-spot transmitter and receiver. Wonder where that went ….. would be fun to build in modern guise.

[AjohnwParticipant @ajohnw51620]

Posted by Geoff Theasby on 01/08/2016 16:16:22:

John, I never heard of a Dirac pulse before, although I knew who he was. Now, having read it up on Wikipedia, my head is spinning, but a picture is worth a thousand words. Just as my Geometry teacher said, "a line has length but no thickness," a Dirac pulse is one occupying zero time with a 100% energy content. Simples! Real life is not so simple though. Gosh, the things I learn in Model Engineering!

 

There is a very clear explanation of why it is used in electronics here Geoff.

**LINK**

As daft as it sounds it simplifies things. I think it's use is demonstrated in one of the Schaum's books

You might find more by looking around at Laplace transforms such as this one which probably  wont help but does indicate the need for partial fractions.

http://people.seas.harvard.edu/~jones/es154/lectures/lecture_0/Laplace/laplace.html%20

No I don't carry that lot about in my head but have used it once or twice.

John

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Edited By Ajohnw on 01/08/2016 17:53:51

[SillyOldDufferModerator @sillyoldduffer]

Posted by Mark C on 31/07/2016 21:12:35:

Steve posted a link to an online tool in his post 1/07/2016 11:52:02

As far as I can see it has not prompted a single response, perhaps no body could be bothered to take a look?

I did, it certainly appears to be the best example of a simple simulator I have ever seen. It took me about 3 or 4 mins to get it doing interesting stuff. It might not simulate a bulb, battery and switch (it might, I never tried?) but it is very easy to use and has building blocks that are easy to edit. It shows flows (voltage/power etc) as moving dots that change in intensity relative to each other and is very interactive. You do have to have a grasp of schematic diagrams but that is par for anything in electrics/electronics.

Take a look and forget about what constitutes beginners or advanced, this shows you visually what is occurring, just like engineers like it!

Mark

I checked it out last night Mark and will be playing with it again later. I had no trouble getting an oscillator going. It seems to be a pretty good way of trying circuits without actually building them, and you don't have to be a genius to use it. Nor do you have to install anything.

Thanks to Steve for highlighting it.

Cheers,

Dave

[Geoff TheasbyParticipant @geofftheasby]

Hmmm, no it doesn't! Anyway, as a practical radio user, I know that to transmit a true square wave, as in keying Morse code, you need a circuit that will respond without rounding off the corners or spreading out the signal,. This means creating a wider and wider bandwidth in order to accommodate all the higher harmonics, thus getting further and further away from the ideal. Too square and it will 'ring' or oscillate at the 'corners;' of the waveform, giving 'key clicks'. Too round and it will sound muffled and indistinct.

Also, re PW, they also do CDs of collected simple articles and projects, plus two books on Technical for the Terrified, etc.

Muzzer, you too, eh? Join the club! Rob Mannion was giving a talk at Otley Radio Club, and recognised me in the audience. I had to stand up and take a bow!

[Mark CParticipant @markc]

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

[Neil WyattModerator @neilwyatt]

Posted by Bandersnatch on 01/08/2016 17:24:56:

Posted by Gordon W on 01/08/2016 10:36:04:

Bandersnatch- re -red neg. cable- van is corsa, about 10 yrs. old, so modern. Wiring and battery are original. I only found out 'cos I'd flattened the battery and wanted to check the voltage after charging. Battery still good, so not bad for 10 yrs. My fault really, when I took off the plastic cover it was clear that both cables were red and clearly marked + & –. Lesson learnt.

Sorry Gordon, you lost me. Are you sure you replied to the right person/thread?

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

Neil

[Neil WyattModerator @neilwyatt]

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

Neil

[Mike PooleParticipant @mikepoole82104]

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

[MuzzerParticipant @muzzer]

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

[AjohnwParticipant @ajohnw51620]

Posted by Neil Wyatt on 01/08/2016 18:55:50:

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

Neil

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

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

[Mark McCreaParticipant @markmccrea21094]

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

[Anonymous]

Posted by Geoff Theasby on 01/08/2016 16:16:22:

………… a Dirac pulse is one occupying zero time with a 100% energy content. Simples! Real life is not so simple though.

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

[AjohnwParticipant @ajohnw51620]

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

One for Neil

**LINK**

John

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[Geoff TheasbyParticipant @geofftheasby]

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

[Gordon WParticipant @gordonw]

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

[AjohnwParticipant @ajohnw51620]

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

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[Ian S CParticipant @iansc]

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

[Anonymous]

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

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