Saturday 26 January 2019

Electricity, electrons, atoms

At the atom level, as far as we know, everything is made of the the same three things (protons, neutrons and electrons), that is all atoms. I think that there may be something missing between Quantum Physics and Newtonian Physics though, but electronics is closely related to how things that happen at the atomic level, or quantum level interact with things happening at the newtonian or ordinary mechanical level.

Human beings are not able to understand exactly what happens at the quantum level, this isn't a matter of an individual's or a group's intelligence, but it is an issue that is related to how human beings process and receive information in an ordinary mechanical newtonian world and how the senses are used.

In most cases we get our information about what is going on in mechanical or scientific terms, either by seeing something or by hearing something. If the thing we are observing is too small, to far away to quiet, then we have developed devices to overcome this.

We can look at very small things with microscopes, far way things with telescopes, get a hearing aid and so on.

When we go to look at something, we can shine a torch - a stream of protons pointed at the thing, the protons (light) land on the thing, some of the light bounces back and reaches our eyes where a transducer processes the light into electrons which do things we don't yet understand in the electrochemical computer we call our brain.

With electrons, trying to look at them with a photon, trying to determine what they are like, involves throwing photons and other electrons at them. This means there is a strong element of, trying to find out something about a brick by throwing tennis balls and other bricks at it and mapping where any that come back land.
So back to where we were at in the previous post. The thermionic diode. adding another lump of metal to a light bulb. So at this point in the history of the subject we went from understanding electricity to be a flow of something from positive to negative, into being a flow of electrons from negative to positive.

An issue here is that there is both positive and negative charge and to understand electronics to the point where you can make useful things by connecting electronic components together, you have to be able to consider electrons in their own way way.

Simplistically; in an atom:-

An extra electron; causes a negative electric charge.

A missing electron in an atom; causes a positive charge.

The spinning of electrons in atoms cause a magnetic field.

Changing the the energy level of an electron in an atom causes it to give off a photo.

These things work the other way around.

Brushing your hair scrapes some of the electrons of the surface of the hairs and causes a positive charge. So it stands on end, sparks or fails to do anything much.

When a photon is absorbed by an electron it changes the electron's energy level. 

Doing the same thing to a lot of electrons related to atoms in one area produces a measurable effect.

Next up should be a diagram/drawing of an atom.

Whole atoms are very small, you would get about a million lined up across the thickness of a human hair. It's a bit hard to visualise a million, there are about a million seconds in twelve days, so it could be time to count up to a million slowly.

If the nucleolus of an atom was about the size of an egg then the edge of the atom would be about a mile away.

This is a picture representing a single silicon atom, from the point of view of electronics the protons are positive, the neutrons neutral and the electrons negative.

If this atom had 15 electrons and 15 protons then it would be phosphorus

If this atom had 13 electrons and 13 protons then it would be aluminium

14 is the atomic number of silicon. Nothing else has 14.

In electronics situations develop where some silicone atoms have either 13 or 15 electrons and stay silicon.

Wednesday 23 January 2019

Confusion about Ohms Law and the Direction that Electricity Flows In.

In electronics the basic equation is Ohms Law

thing                                    unit

Resistance   R              Ohm   Ω 

Current         I                Amp    A

EMF        E or V                    Volt    V

PD or p.d. standing for potential difference. (the voltage measured between two points in an electric circuit)

EMF standing for, electro motive force, but considered not to be a force although who knows what goes on in the mind. 

As you see it's the voltage where you get the problem.

At the moment, while  a 1.5 volt battery, can be thought of as having a potential difference between each end and an internal resistance, most of the time, just think of it as a 1.5 V battery.

I guess one way to look at this is the EMF is the voltage at the battery terminals or generator, when nothing is happening, no current is flowing. As soon as current is flowing then the internal resistance of the battery means that the voltage at the end of the battery becomes a PD. Strictly speaking that would include measuring it as current would flow around the circuit to move the meter.

Electricity in electronics is mostly a flow of electrons around a closed circuit. The electrons flow from the negative end of the battery through the device (torch, phone, game, etc) and into the positive end of the battery.

Unfortunately when electricity was being discovered it was decided that the flow was from positive + to negative - and this is called conventional current flow. I would say that if you are going to manage to understand some electrical components properly, then best just accept that electricity is a flow of electrons going from negative to positive and that the arrows on diodes and transistors are all the wrong way round.    

Trying to hold the flow of holes in your head along with everything else, well you know how it is with holes in the head.

So Ohms law.
 Some tips.

V never goes at the bottom.

Getting the battery symbol the right way round can be remembered by breaking the long line in the symbol in half to form the + symbol. 

The direction electricity flows in was discovered by Edison's assistant Hammer in 1880. This is a complicated business (the discovery that is) Discovered before by English scientist Frederick Guthrie in 1873.

But the Hammer Edison one is easy to understand and involves putting another  bit of metal in a light bulb with a wire leading outside the light bulb.

The electrons excited by the heat of the element will flow toward the extra bit of metal if a circuit is completed. They won't flow the other way, it's like a one way street, and called a diode.


Sunday 20 January 2019

Electronics Introductory post

My intention here is to write something about learning electronics, like so many things what sparked this off was an error. I put "transistor polarity" into Google and pretty much the first site the came up had a polarity error in one of the diagrams explaining polarity.

I started learning about electronics in the 1960s, so I have decided to brush up my basic knowledge on the subject.

I studied electronics at Lord Mayor Treloar College for the Disabled from around 1966 to around 1970 and went on to work as a sort of mechanic until around 1980 when I had a career change and became a sort of shop assistant in various bookshops.

My main blog is mostly about where I live and what I get up to here is the link to it

So why the name Slowhump? two reasons really.

One is because of the mistake that started me off, an aunt of mine mistook a road sign
for meaning that we were entering a village of that name.

The other is that I thought it would be easy for people to spell, remember and find it.

Back in the 1950s and 60s I had a disability which made my hands shake and because of that I avoided writing anything down on paper, later on I discovered that a lot of people learn to spell by remembering the shape they make when the write it on paper. 

I think I would have been one of those people, let's say I am very glad that computers have a spellcheck.

Back in the days when I worked as a sort of mechanic, I noticed that a lot of the other people I worked with, particularly in factories, were also very reluctant to write things down and that when they did - spelling as an issue.

Of course now mechanics and engineers write with their thumbs on their smartphones and apart from exams hardly ever have to write on paper.

I would recommend anyone who is learning electronics for exams to write all their notes out in neat writing on paper. It helps to remember what you learnt and makes it easier to pass exams.

I am doing this with in conjunction with a Facebook group here is the link 

So the good news is electricity is a flow of electrons from one atom to another. 

The bad news is that no one knows what an electron is.     

Do not Adjust Reality Your Mind is at Fault

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