Basic electronics help

[Russell EberhardtParticipant @russelleberhardt48058]

Most of these analogies break down under many real world conditions.

Inductors and capacitors are fairly easy to understand in ac circuits where they act a bit like frequency dependent resistors (although to be accurate you have to delve into complex numbers). What is more difficult is to understand their actions under transient conditions, for example ignition coils generating high voltages when the circuit is broken. To predict what happens under transient conditions requires the use of calculus or some computer software such as Spice.

Russell.

[MuzzerParticipant @muzzer]

Funny you should say that – an ignition coil generating high voltage when the current is interrupted is actually directly analogous to the water hammer effect. No fancy maths required in that instance!

Murray

[martin perman 1Participant @martinperman1]

Russell,

As a beginner they work well enough for me

martin P

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Muzzer on 27/01/2015 18:53:00:

Funny you should say that – an ignition coil generating high voltage when the current is interrupted is actually directly analogous to the water hammer effect. No fancy maths required in that instance!

Murray

Agreed, unless of course you need to calculate the voltage reached and the energy in the spark.

Actually as an electronics engineer I sometimes use electrical analogies to help me understand mechanical problems

Russell.

Edited By Russell Eberhardt on 28/01/2015 08:34:01

[Roger HartParticipant @rogerhart88496]

Perhaps buy one of those kids electronics kits. The sort that make a radio and a noise-maker etc. Not expensive and if you poke around a working circuit with a multimeter you get a feel for the voltages involved (strictly low volts till you are up to speed). You might like to poke around inside an old battery transistor radio and take it to bits to see what it is made of. Experience is directly proportional to the amount of expensive kit ruined…..

[Neil WyattModerator @neilwyatt]

The spark gap could be compared to a safety valve fitted with a venturi

<stir stir>

Neil

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Roger Hart on 28/01/2015 08:50:31:

You might like to poke around inside an old battery transistor radio and take it to bits to see what it is made of. Experience is directly proportional to the amount of expensive kit ruined…..

That's an excellent way to learn about analogue electronics. Not quite so easy to see what's happening with digital stuff though.

When I was eleven I followed a BBC Childrens TV series showing how to build a one valve radio. It never worked so I started reading to find out why. I then started collecting scrap radios and televisions, repairing some and dismantling others to build other projects including an oscilloscope using an old radar tube and a bunch of EF50 valves out of televisions.

The Arduino designer started in a similar fashion taking electronic toys apart and, when he was given a Z80 computer for his birthday he used it to control his welder.

Russell.

Edited By Russell Eberhardt on 28/01/2015 10:51:09

[Roger HartParticipant @rogerhart88496]

You could try one of the free electronics simulators. I only have experience of Tina and LTSpice for analogue – not bad but Tina is no longer free (I think) but you have to have some idea what you are looking for and trying to do. The instructions are not very step-by-step. Wikipedia has a list to try out.

If you try utube RLC Series Circuit Simulation you will see someone using a simulator to put together a simple RLC circuit and analyse it. Useful as a start but a bit boring and the aim like many others is to sell you a simulator.

I was about to suggest getting a simple oscilloscope – the older tube type is pretty robust and intuitive to use but nowadays a bit pricey at about £100+ for a usable one. Being a bit of an antique I have not tried the digital type.

[MuzzerParticipant @muzzer]

Looks as if you can get a vaguely decent looking scope for just over £100 from Rapid Electronics, so if you are prepared to take your chances you may even get something better from a famous website. There are even USB-based scope modules for half that price on Amazon UK.

Murray

[Peter BondParticipant @peterbond14804]

May I suggest – for analogue and older digital electronics – a copy of Horowitz and Hill? 2nd edition is woefully out-of-date for the newer digital (written in an era when 8-bit held sway and 16-bit was fairly new) but transistors, inductors and the likes haven't changed all that much. It was a required text at university and it is written in a pragmatic and accessible fashion.

3rd edition is supposed to be out this year, we'll see.

Thinking about it, I probably ought to see what it says about 3 phase power!

[Cornish JackParticipant @cornishjack]

Having searched widely for suitable info sources, have plumped for one of the 'for Dummies' series which seems, so far, to be pitched at exactly the right level! I have purchased both the Electronics and Arduino versions and will plough through them at my own, snail-like, pace.

The electronics version (and this forum) have already thrown up a head-scratcher … 'inductor' – WTH is an inductor??? Book seems to say that it is just another name for what we used to call a 'coil', but references here don't seem to match that No doubt it will all become clear eventually.

60 years ago I 'blanked' electronics and went into 'learn by rote' mode after being told by our instructor that he didn't know which flow direction (Pos to Neg or Neg to Pos) was correct!! Maybe the interim years of confusion can be improved on!

Rgds

Bill

[Russell EberhardtParticipant @russelleberhardt48058]

Yes, an inductor is what used to be known as a coil, just as a capacitor used to be called a condenser.

An inductor can be a plain coil of wire or it may have a "core" of iron or ferrite to increase it's inductance.  Two inductors linked become a transformer.

I think it would be good to go through the Electronics book first.  It will make the Arduino one easier.

Russell.

Edited By Russell Eberhardt on 29/01/2015 14:57:11

[Neil WyattModerator @neilwyatt]

> Horowitz and Hill

Still find mine invaluable.

> he didn't know which flow direction (Pos to Neg or Neg to Pos) was correct!!

No-one does. Electrons flow from neg to pos, but by convention current goes the other way.

You choose

Neil

[Anonymous]

Don't be fooled into thinking that only coils have inductance; everything has inductance, including a straight piece of wire. Of course the inductance of a wire is small, but can be significant when dealing fast changing currents as in power electronics.

Andrew

[john fletcher 1Participant @johnfletcher1]

Before considering buying a scope I suggest you join Vintage Radio.Org its free. On Vintage Radio there are people who really understand and can explain electronics in every day terms and where you might pick up a scope for a lot less than £100 but do you really need a scope. An £8 Aldi multimeter is useful aid, also on ebay there is another useful piece of test gear, which for about £12 you can test resistors, capacitors, inductors and transistor quite accurately. As a starter project, how about making a workshop power supply. Almost all the components you will need can be obtained from an old washing machine speed board or an old audio amplifier or an old type TV. Get a soldering iron and solder sucker and start removing components and then identifying them. You will learn a lot that way especially when fault finding.Ted

[Neil WyattModerator @neilwyatt]

I got my 50MHz twin trace Hameg off Ebay for £35. It's fine for most of what I do.

Neil

[martin perman 1Participant @martinperman1]

Gentlemen,

What about these reader units that plug into laptops to turn them into sillyscopes with software.

Martin P

[Neil WyattModerator @neilwyatt]

Some are very good, some aren't. make sure it's optically isolated.

These are good: http://www.picotech.com/products/oscilloscope

Don't risk the ones that just use a mike input.

Neil

[MuzzerParticipant @muzzer]

Bad echo in here. That's what I suggested in the previous page….

[Anonymous]

Posted by Muzzer on 29/01/2015 21:38:24:

Bad echo in here. That's what I suggested in the previous page….

Semebody accidentally has their foot on the reverb pedal?

Andrew

On 'scopes I've got a Tektronix TDS series digital 'scope for day to day work. It's pretty good, although the probes aren't the most robust, and being digital has some nice features like one shot capture and a FFT function. But, you do need to be wary about being told porkie pies due to aliasing. The Pico 'scopes look good; they're in the next unit to the tool emporium I use in Eaton Socon, may be I should look in? In my younger days I lusted after the Tektronix 7000 series 'scopes, but there was no way I could afford them.

[Geoff TheasbyParticipant @geofftheasby]

Depends what you wish to measure. You can get virtual oscilloscopes and other test gear that work at audio level (Up to maybe 20 kHz) which you can download from t'internet, some free, some not, and beware of viruses!

Geoff

[martin perman 1Participant @martinperman1]

Andrew,

Where in Eaton Socon is the tool emporium you use and whats it called, I wouldnt mind a look as I only live a few miles away, approx 10 miles.

Martin P

[Russell EberhardtParticipant @russelleberhardt48058]

Posted by Andrew Johnston on 29/01/2015 15:29:16:

Don't be fooled into thinking that only coils have inductance; everything has inductance, including a straight piece of wire. Of course the inductance of a wire is small, but can be significant when dealing fast changing currents as in power electronics.

Andrew

Of course, and if you consider the distributed capacitance of a straight wire it becomes a transmission line. However, for the OPs purposes I think it's best to ignore such things for now

Russell.

[Gordon WParticipant @gordonw]

This thread shows one of the real problems for us people who are trying to learn. Someone asks for Basic electronics help, and in 5 mins. you are all going on about oscilloscopes and obtuse inductance theories.

[Martin KyteParticipant @martinkyte99762]

I'm with you on that Gordon and I'm a professional. He really only asked for a book recommendation.

Higher Electrical Engineering by Sheperd Morton and Spence is good.

web version here

https://archive.org/details/HigherElectricalEngineering

Also

Electronics Designers Handbook by Hemmingway

Also the web is FULL of explanations of everything.

http://www.learnabout-electronics.org/

is packed full of easy to access stuff

Take Inductors for example pdf at

http://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=4&ved=0CDkQFjAD&url=http%3A%2F%2Fwww.learnabout-electronics.org%2FDownloads%2Fac_theory_module03.pdf&ei=H1XLVIWeCaXU7AbbzID4CQ&usg=AFQjCNGZI6OhIaBcEELQ-Kivd8hmwBoaPg&bvm=bv.84607526,d.d24

tell you all you would want to know as an interested amateur

regards Martin

Martin

[Author]

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