
How transistors really work (1995) - apsec112
http://amasci.com/amateur/transis.html
======
pdkl95
I like William Beaty's explanation electrical topics. In particular, his
history[1] of the 3-prong mains plug I found very interesting.

Also, I still want to see an actual electro-electret[2].

[1]
[http://amasci.com/amateur/whygnd.html](http://amasci.com/amateur/whygnd.html)

[2] [http://amasci.com/elect/mcoils.html](http://amasci.com/elect/mcoils.html)

~~~
wbeaty
Mcoils article was much longer, but I never made the GIF diagrams for the
second half. Do this: make a small half-inch parallel-plate capacitor with a
10ft thick dielectric. Use the insulating dielectric as an "AC conductor."
Break it in two to form an off-switch, and force the fractured ends back
together to complete the circuit.

I do have a short piece of PZT piezo ceramic rod from eBay. But I still
haven't tried using it to complete an AC circuit, or even stuck it on top of a
Tesla coil. At high freqs, high-K piezo-ceramic insulators are a good
conductor: a long, long filament of capacitor-dielectric which, in theory, can
be wound into an AC electromagnet coil ...made of insulator. (Or, when put on
top of a Tesla coil, I expect sparks to shoot out of the insulating ceramic
tip!) But not nearly as fun concept as electro-electret solenoids that should
attract rice crispies and small bits of paper.

I did build the chain-of-rings transformer, the waveguide for 60Hz. In a
surplus shop I found a handful of big transformer cores; those tape-wound
split-core type. I could pass copper rings through these (made some #10-gauge
wire loops), using cable-ties to clamp the C-cores into closed rings. I drove
one end of the chain with 1000 amps from a soldering gun tip. The other end
was 30 turns of wire-wrap wire, and would light up a little 3v pilot light. I
think there were six iron cores and five copper rings in the chain.

Of course if you want the ultimate chain, you'd need alternating rings of
piezo ceramic and ferrite. Figure out how much horsepower could be sent along
the floppy chain before it started heating up too much!

Handy note: if you need ~1000 amps AC for anything, just screw a short loop of
#12-gauge solid wire into the end of your 300-watt soldering gun. Make a
little loop coil, use it to demagnetize your screwdrivers. It's not 1000 turns
of one ampere, it's one turn of 1000 amperes. Pass the conductor through a
pair of tapewound C-cores and they slam together with 100s lbs force. (Measure
it with a clamp-on ammeter, if your ammeter goes that high.)

For my next trick, I will shoot a smoke-ring made out of Luminiferous Aether
across the room. But first I'll need a big deep hat, from which I'll have to
pull two new Maxwell's equations! :)

------
analognoise
Electronic Principles, Gray & Searle, 1969 edition.

[https://archive.org/details/ElectronicPrinciples](https://archive.org/details/ElectronicPrinciples)

All explanations do suck, but I don't think this explanation is an exception.

If anyone wants to read along with me, hit me up. I see lots of interest in
ankle-deep explanations, but where is the fun in that?

~~~
nickpsecurity
I don't know crap about analog electronics. Just got Electronic Principles by
Malvino as a start. Authors explanation seems clearer than anything I've seen
so far. Even contradicts some online descriptions.

So, I downloaded your book. Not time for deep explanations for now but which
part(s) cover the same thing so I can do a comparison?

~~~
analognoise
Wanna start a reading group? I'll give you a better answer later ;)

~~~
nickpsecurity
Not up for that commitment as I'm already bogged down. I could spare enough
for the article and a few comments but not much more than that. Thanks anyway.

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aparks517
For anyone interested in semiconductor physics, Bob Widlar's "Introduction to
Semiconductor Devices" is a delightful and accessible read.

~~~
bgilroy26
Have you ever seen a copy? According to Google, the book is totally
unavailable. It isn't listed on Amazon or Alibis. I would love to get my hands
on one, Widlar sounds a lot like Richard Feynman

~~~
analognoise
Thank ARPANET for them internets:

Part 1: Introduction to Semiconductor Devices:
[http://archive.computerhistory.org/resources/access/text/201...](http://archive.computerhistory.org/resources/access/text/2014/05/102718662-05-01.acc.pdf)

Part 2: Conduction in Solids
[http://archive.computerhistory.org/resources/access/text/201...](http://archive.computerhistory.org/resources/access/text/2014/05/102718662-05-02.acc.pdf)

Part 3: The PN Junction
[http://archive.computerhistory.org/resources/access/text/201...](http://archive.computerhistory.org/resources/access/text/2014/05/102718662-05-03.acc.pdf)

Part 4: The Junction Transistor
[http://archive.computerhistory.org/resources/access/text/201...](http://archive.computerhistory.org/resources/access/text/2014/05/102718662-05-04.acc.pdf)

Part 5: The Fabrication of Diodes and Transistors
[http://archive.computerhistory.org/resources/access/text/201...](http://archive.computerhistory.org/resources/access/text/2014/05/102718662-05-05.acc.pdf)

Part 6: Transistor Circuits
[http://archive.computerhistory.org/resources/access/text/201...](http://archive.computerhistory.org/resources/access/text/2014/05/102718662-05-06.acc.pdf)

Contacted the Air Training Command to see if there's a way to make sure it's
the whole document; will update this if any pieces are missing.

~~~
bgilroy26
Woohoo! Thank you!

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mojuba
And not a single word on how exactly electron flow and the field relate to
each other? This can't possibly claim to be a "better" explanation.

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calinet6
It just dawned on me that "current" is exactly like the flow of water in a
river, also called "current." It's already a flow of charge.

~~~
luxpir
It's called the _intensité (du courant)_ in French, which might explain the I
in the equations, instead of an expected C or A.

------
nickpsecurity
Great write-up! Things are more clear now.

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thrownaway2424
That's bullshit. There's actually a little man inside the transistor pulling a
lever.

[http://media.tumblr.com/tumblr_luy74c89IH1qf00w4.png](http://media.tumblr.com/tumblr_luy74c89IH1qf00w4.png)

~~~
ObsoleteMailMan
Transistor man!

~~~
hatsunearu
Little bit of context:

The "Transistor Man" was I believe first introduced in The Art of Electronics
(great book btw, the third edition just came out). An extremely simple model
of a bipolar junction transistor in the linear region states that the current
going from the Base to Emitter (Ib) and the current pulled from the collector
(Ic) is related by: Ic = beta * Ib. (beta is another name for hFE, at DC)

The "Transistor Man" continuously monitors Ib, multiplies by beta, and adjusts
the adjustable resistor until Ic = beta * Ib.

Obviously, you can't make a resistor with a resistance below 0, so when it
hits rock bottom Ic cannot reach beta * Ib, which models saturation.

Note that this "model" is insanely horrible because hFE/beta increases and
decreases depending on the amount of current, by temperature, and most
importantly from manufacturing tolerances. Good transistor circuits (like the
AoE book teaches you how to build) work the same way regardless of hFE as long
as it's in the reasonable ball park.

~~~
wbeaty
As Win Hill says, his "transistor man" is later discarded, and replaced by
voltage-based design which eliminates hfe, relying on Vbe and Ebers-Moll
equation.

This makes his book even more excellent. And the lab book for AOA goes much
farther, directly exposing the many mistakes caused by "current amplifier"
design philosophy based on hfe.

Look inside a BJT op-amp, where diff-input is voltage-based. And the many
Current-Source sections employ the transconductance model, Vbe-based
explanations, not hfe.

Heh, the actual "transistor man" is made out of voltage; he's the base voltage
Vbe, and he adjusts the thickness of the depletion layer inside the emitter
junction. The depletion layer observes Ib, changes its thickness in response,
and this thickness then determines the value of collector current Ic. Actually
Ib cannot affect Ic or vice versa, otherwise we'd just have resistor action,
not transistor action.

 _" As a young engineer struggling with my circuit designs in the mid 60's
(remember the h parameters?), a wise experienced teacher sat me down with a
single sheet of paper for 30 minutes and preached the value of Ebers-Moll and
Re. What's the gain of a common-emitter amplifier stage? Easy, RL / Re. And Re
is 25 ohms at 1mA.

"Oops, Re = VT/IC = 25mV/IC, and changes with current, causing distortion? OK
add a degenerating resistance, RE - now the gain is RL / RE+Re, and I can
quickly calculate my gain and predict the distortion level for my choices of
RE. Try that kind of easy analysis with the βeta approach.

"So I changed my design approach and suddenly things start working as
predicted. That is to say, I could reliably engineer instead of empirically-
develop my designs. I could also safely do more complex designs."_ \- 2011
Winfield Hill [http://cr4.globalspec.com/comment/720374/Re-Voltage-vs-
Curre...](http://cr4.globalspec.com/comment/720374/Re-Voltage-vs-Current)

