# Electronics for the right-brained

Discussion in 'General Electronics Discussion' started by wingnut, Sep 7, 2012.

1. ### wingnut

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Aug 9, 2012
Can anyone recommend an electronics course/book for right brained dummies, preferably just giving overall concepts, no numbers or maths, and with lots of analogies and pretty pictures - sort of the opposite of Horowitz and Hill.

Thanks in anticipation.

2. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,448
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Jan 21, 2010
How about you get yourself a subscription to an electronics magazine? Something like Silicon Chip perhaps. Some of these can be subscribed to on-line, so there's no massive cost of postage.

There used to be a heap of titles (Talking Electronics was one) that covered basics. Their web site is still updated and has lots of useful stuff.

1,114
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Aug 13, 2011
That's not really possible. Electronics is an application of physics and requires some math. These are the closest to your requirement that I know of.

Getting Started in Electronics: http://www.amazon.com/gp/aw/d/0945053282

Make: Electronics: http://www.amazon.com/gp/aw/d/0596153740/ref=mp_sim_p_dp_1?pi=SL500_SY125

Electronics for Dummies: http://www.amazon.com/gp/aw/d/0470286970/ref=mp_sim_p_dp_3?pi=SL500_SY125

4. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,448
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Jan 21, 2010
Yeah, there is a limit as to how much electronics you can do with no mathematics at all. (And that limit is that you are limited to building circuits designed by others, with the component values they have chosen, and with only notional understanding of the circuit operation)

I'm not saying that that means you can't do anything. It's a point where many hobbiests get to.

The next step is the basic arithmetic of ohms law, which (frankly) you really aren't safe to be let work unsupervised unless you know and understand this.

When you say "no numbers or mathematics, I hope you don't mean this.

Simple algebra and arithmetic can carry you a long way, as it is all that is needed to understand things like gain of transistors, much work with op-amps, and pretty much all the DC circuit operation you can handle.

However for *real* understanding, you need to be able to work (at least once) with various "higher" mathematical processes. These eventually (most often) turn out to produce more simple arithmetic, but to understand how to apply them it is best having worked through the heavy math at least once.

Ohms law, for example, is a simplification of some really tricky math. It is simplified after making certain assumptions that apply most often in the real world to most things.

As has been suggested before, H&H is actually *very* light on with the math. Sure, it contains some of the formulae, but the text doesn't require that you understand them (other than for the first chapter -- but you can ignore that if you're comfortable with things like ohms law and resistors in series and parallel).

I'll accept that H&H is not the book for you, but without some math, you're going to limit your designs abilities to batteries, switches and incandescent globes.

5. ### wingnut

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Aug 9, 2012
Thanks Steve - talking electronics is about the simplest explanations I have found so far (also falstad's Java applets).

I do have a working knowledge of Ohms law as well as calculating resistance in series and parallel, the mathematics of potential dividers etc. and do fall back on this as a last resort.

Where I am struggling is to look at a component or set of components (circuit) and then visualize in my mind's eye what they are doing there. Are they multiplying current, or multiplying voltage, or filtering out this signal, or amplifying that signal. The how much it is amplifying by can come later.

And to make things more complicated, most circuits seem to have changing voltages which sends a wave of changes rippling through the whole circuit. Its like trying to visualize a movie rather than a photograph - if that makes any sense. First prize would be to find a site or book which simplifies things down to that level.

And KJ6EAD, I will check out the books you recommended and see if the "Dummies" they wrote for are the dummies I had in mind. Maybe I should start in the children's section of the library.

Last edited: Sep 8, 2012
6. ### donkey

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Feb 26, 2011
wingnut just a heads up, I have the for dummies book and I can say not the best read really.
get a book that has circuits in it and explains how they work. for dummies has little in the way of this.
also a while ago I posted in the members section about a live chat using google chat if you ever get bored enough and want to bounce ideas of me then feel free. I am learning myself but I have found 2 very experienced members that are willing to help me out when it gets above my head (which is pretty quick lol)
to add to that there is the obvious choice of using the tutorial part of this site. that gives us all a reference to work of. if for example you link us to the ac theory page then we can all see it, whereas not all of us have access to the make series or the for dummies series of books

7. ### wingnut

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Aug 9, 2012
Thanks donkey - I will take you up on that offer.

Already, with the help of this forum, electronics is making a lot more sense.

8. ### wingnut

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Aug 9, 2012
The thing that a right-brained student like myself is looking for is the bare-bones or minimal amount that one needs to know about something to understand it. We don't revel in detail.

Since I have not been able to find a site with minimalistic amounts of info on electronic components and circuits, I have decided to have a stab at it myself regarding transistors. It is what I consider all that one needs to know, to fairly adequately understand and work with transistors. Some facts may be omitted or just plain wrong, but that is where some on this forum could contribute.

Transistors...

* are electronic switches or amplifiers
* amplify current not voltage
* current flows in the direction which the emitter arrow points
* have three legs, emitter (e), base (b), collector (c)
* like diodes have to be protected with resistors
* the base needs about a 1k resistance
* the main current flows through the emitter/collector legs
* a resistance of about 470 ohms must be attached to e or c to limit current
* the emitter current (Ie) is the sum of collector (Ic) and base (Ib) currents
* Ie = Ic + Ib
* there are two types of transistor, npn and pnp
* In a npn, Ic and Ib flow in, combining to form Ie
* In a pnp, Ie flows in and splits into Ic and Ib flowing out
* In a npn, the base must be "p" positive to switch the transistor on
* In a pnp, the base must be "n" negative to switch the transistor on
* The positive or negative is relative to Ve or emitter voltage
* A pnp must have Vb = Ve - .6V ("n" means negative or minus) to switch on
* A npn must have Vb = Ve + .6V ("p" means plus or positive) to switch on
* when switched on completely, transistors are called "saturated"
* when Vb is about .75V above (npn) or below (pnp) the Ve, saturation occurs
* when Vb >.6V and Vb <.75V the transistor acts as a current amplifier
* the amount which a transistor amplifies the base current by is called its beta value
* the beta value is also known as the Hfe
* the beta or Hfe is commonly around 100 but varies widely even in supposedly similar resistors
* transistors are sometimes called BPJ's or bipolar junctions
* transistors have about 20 ohms resistance and drop voltage by 0.7V
* power transistors are bigger (physically) than low power transistors.
* a low power transistor passes <0.5A.
* an example of a general purpose, low power npn transistor is the 2n222 or BC547
* an example of a general purpose, low power pnp transistor is the BC557
* an example of a general purpose, high power npn transistor is the TIP29 or TIP41
* an example of a general purpose, high power pnp transistor is the TIP42 or TIP30

Any corrections, alterations or additions (even criticisms of this approach) would be welcomed.

Last edited: Sep 9, 2012

1,114
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Aug 13, 2011
Your approach would convert the learning effort on your part into a massive teaching effort on our part and would still result in frustration. A more traditional method starting with basic math and algebra would yield real understanding and ultimately require less effort.

I don't know where you picked up the notion that you're "right-brained" but the fact that you can compose full sentences on this forum proves it false.

10. ### wingnut

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Aug 9, 2012
KJ6EAD you are right about the traditional method of teaching being maths based - which is great if one likes maths. We have simulators these days to handle the maths.

Folks who write books for dummies often include complicated maths - which us dummies buy because we are dummies.

My background is science heavy, but maths light - which is why I am looking for sites which teach electronics from that approach.

11. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,448
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Jan 21, 2010
by which you mean silicon bipolar junction transistors, not jfets, mosfets, or any of the other less common transistor types.
can be used as
more accurately, they use one current to control another
well, actually it flows in exactly the opposite direction since the arrow points in the direction of conventional current which is backwards. But yeah, since we can think about conventional current, the arrow points that way.
yes, usually, but some have only 2 (typically optical devices)
no
no
yes (normally)
no
normally
that's what you just said, but what about leakage from the collector to the base?
with the assumption in my first line above
more restatements of stuff above
more restatement, but "splits", and "combines" are not correct understanding
no. It must be positive wrt the emitter. Both may be -ve, just the base may be less so.
see above, but backwards
yes
no. approximately 0.6V, but it depends on some other factors. Also note that this is specific to silicon transistors (not that you see too many others)
see above
no (it's not quite that simple)
no
Remember that you spoke about transistors being current devices above, and now you're talking voltages.
It's not quite that simple, but this is the definition in one configuration
of course, there's hfe and hFE. They refer to forward current gain in a particular configuration. But yes, that equation holds
no
no. There are many types of transistors, you've simply picked out BJTs (and silicon ones) for this list.
not sure what you mean here
often, but not always
only if you define it as such. I can show you some very small transistors capable of very high currents. What differentiates them is the power they can dissipate (hence why one might call them low or high power). Even there, this is a continuum.
OK
OK
no, this is medium power, look at something like the venerable 2N3055 -- especially in TO-3.
What about the MJ2955? As I said, there is a continuum of values here. Another important one is the various Vce specifications. Can the transistor be used in a 30V circuit, 50V, 80V, 200V, or 1000V circuit?
Your list represents a set of assumptions and generalizations you (or someone else) has made. Pretty much all of them are wrong in some form (and it would take pages to get some of them close to right).

To gain further understanding you need (many things, but one is) to see an explanation of the physics of a transistor. You don't need to understand it completely or be able to regurgitate it, but the list above tells me you really haven't seen it.

Possibly a quick look at the other types of transistors so you don't think BJT's are the be all and end all of them.

I just flipped through the first 10 or so pages of the introduction to transistors in Horrowitz and Hill. The most advanced mathematics was:

1) simple arithmetic (division and multiplication)
2) the use of the delta symbol meaning "change in"
3) the use of the symbol || meaning "in parallel with (so R1 || R2 means 1/(1/R1 + 1/R2) -- just a bit of shorthand)

I could point you to other books that have pages of calculus describing the same things.

12. ### Raven Luni

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Oct 15, 2011
Actually maths is more right brained if you ask me. Thats why I cant do it

13. ### wingnut

242
9
Aug 9, 2012
Steve

Thank you for taking the time to give feedback.
I know that you must be correct even though I may not be able to see it yet.

One has to start somewhere with a mental model of the transistor. That summary was my mental image as of the 9th Sept, which will evolve into a better understanding with time. If one is not designing life-support equipment, are my points not mostly correct?

Flipping through H&H, circuits which made no sense a month ago, I now have some idea as to what these do.

You wrote...
"I just flipped through the first 10 or so pages of the introduction to transistors in Horrowitz and Hill. The most advanced mathematics was:..."

You are right - it was OK up till page 10. Which reminds me of Jurassic Park, where it all starts well, then the screaming begins - in this case on page 11 where he tries to explain Thevenin. I have read P11 half a dozen times but he has lost me.

You are right about there being far worse than H&H though. They really are making an effort to be as simple as possible. To be comprehensive, they are forced to dive into heavy maths - which is what formal, tertiary education (rightly) does. That approach would, however, dampen my passion for electronics and programming.

14. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

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Jan 21, 2010
Skip Thevinen and all of chapter 1. Skip ahead to the chapter on transistors.

15. ### wingnut

242
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Aug 9, 2012
Steve at...
http://www.electronics-tutorials.ws/transistor/tran_8.html
they compare transistors. I copied it below.

Points 1 and 2 confuse me.

On point 2..... I would have thought that BPJ's have a high current gain or beta value of up to 450. This is high. Do they mean that FET's are higher still?

On point 1.... A BJT amplifies current which can be turned into a voltage across a resistor, or by switching off, across itself. Or do they mean that a BJT requires a higher Vce voltage than a FET's Vds?

When I see a circuit with a FET, I ask myself why they would use that instead of a BPJ? Is it usually that there is high input impedance and a low input current that they choose to use a FET?

Differences between a FET and a Bipolar Transistor

Field Effect Transistors can be used to replace normal Bipolar Junction Transistors in electronic circuits and a simple comparison between FET's and transistors stating both their advantages and their disadvantages is given below.
....... Field Effect Transistor (FET) ..Bipolar Junction Transistor (BJT)
1 Low voltage gain................... High voltage gain
2 High current gain................. Low current gain
3 Very high input impedance.. Low input impedance
4 High output impedance ........Low output impedance
5 Low noise generation........... Medium noise generation
6 Fast switching time............... Medium switching time
7 Easily damaged by static....... Robust
8 Some require an input to turn it "OFF" Requires zero input to turn it "OFF"
9 Voltage controlled device..... Current controlled device
10 Exhibits the properties of a Resistor
11 More expensive than bipolar........ Cheap
12 Difficult to bias...................... Easy to bias

16. ### (*steve*)¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥdModerator

25,448
2,809
Jan 21, 2010
Well, there's high and there's HIGH!!!

Sure 450 for a BJT seems high (and I'm sure I've seen a device with a max hfe of 800). If you look at darlington configurations (don't bother with this now) then gains in the tens of thousands are distinctly possible.

However, a BJT requires a base current (no matter how small) to control a larger collector current.

If you look at FETs, you will notice that rather than being current controlled, they are voltage controlled. To simplify things somewhat, this means that no current flows into or out of the gate terminal. As such, the current gain is effectively infinite.

In real life, there are leakage currents and other factors, but still, the current gains are astonishingly, mind-bogglingly high. They're so high that you'll almost never see figures quoted, they become so high as to be meaningless.

No. It's all about the control terminal.

Let's think about the base of a bipolar transistor. It is forward biased in normal operation, and the Vbe barely changes as the current through it increases. It may change from 0.62 to 0.6205 V (say) as the current changes from 1 to 2 uA. and assuming a gain of 100, the collector current may change from 100 to 200uA (0.1 to 0.2 mA. If the power supply is 12V, and the load resistor is 47k, the voltage at the collector changes from 7.3V to 2.6V. That's a change of 4.7V for an input voltage swing of 0.0005V, a gain of 9400.

In contrast, With a mosfet, the gate terminal may need to swing several volts to change the device from being off to on, but the current it might allow to pass through it could be tens of amps. In this case, even if the drain voltage swing all the way from 12V to (say) 0.5V with an input swing of 2 volts, the voltage gain is about 6, bit assuming an input current of (say) 10 nA, and an output current of 1A, the current gain is around 100,000,000.

OK, skim over the details, but in these examples, you can see that a BJT has a current gain of 100 compared with 100,000,000 for a mosfet, and the voltage gain is 9600 vs 6.

That's one reason. Another is that they are happier switching moderately large currents. It often boils down to current gain. This goes hand in hand with being able to switch very close to supply rails, and that can be important too.

17. ### davennModerator

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Sep 5, 2009
No, where ever Steve has said No, it really is No you maybe were running at ~ 50%

Its all good tho mate you are asking questions doing some reading and learning and thats what it is all about !
Keep reading H&H and when you find things you dont understand just ask questions on those points ad you have started to

cheers
Dave

18. ### wingnut

242
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Aug 9, 2012
Thanks for the clarification Steve, and the encouragement Dave.