How transistors work – Gokul J. Krishnan

How transistors work – Gokul J. Krishnan

Modern computers
are revolutionizing our lives, performing tasks unimaginable
only decades ago. This was made possible by a long series
of innovations, but there’s one foundational invention
that almost everything else relies upon: the transistor. So what is that, and how does such a device enable
all the amazing things computers can do? Well, at their core, all computers
are just what the name implies, machines that perform
mathematical operations. The earliest computers were manual
counting devices, like the abacus, while later ones used mechanical parts. What made them computers was having
a way to represent numbers and a system for manipulating them. Electronic computers work the same way, but instead of physical arrangements, the numbers are represented
by electric voltages. Most such computers use a type of math
called Boolean logic that has only two possible values, the logical conditions true and false, denoted by binary digits one and zero. They are represented by high
and low voltages. Equations are implemented
via logic gate circuits that produce an output of one or zero based on whether the inputs satisfy
a certain logical statement. These circuits perform three fundamental
logical operations, conjunction, disjunction, and negation. The way conjunction works is an “and gate”
provides a high-voltage output only if it receives
two high-voltage inputs, and the other gates work
by similar principles. Circuits can be combined to perform
complex operations, like addition and subtraction. And computer programs
consist of instructions for electronically performing
these operations. This kind of system needs a reliable
and accurate method for controlling electric current. Early electronic computers,
like the ENIAC, used a device called the vacuum tube. Its early form, the diode, consisted of two electrodes
in an evacuated glass container. Applying a voltage to the cathode
makes it heat up and release electrons. If the anode is at a slightly
higher positive potential, the electrons are attracted to it, completing the circuit. This unidirectional
current flow could be controlled by varying the voltage to the cathode, which makes it release more
or less electrons. The next stage was the triode, which uses a third electrode
called the grid. This is a wire screen
between the cathode and anode through which electrons could pass. Varying its voltage makes it either repel or attract the electrons
emitted by the cathode, thus, enabling fast current-switching. The ability to amplify signals
also made the triode crucial for radio and long distance communication. But despite these advancements,
vacuum tubes were unreliable and bulky. With 18,000 triodes, ENIAC was nearly
the size of a tennis court and weighed 30 tons. Tubes failed every other day, and in one hour, it consumed the amount
of electricity used by 15 homes in a day. The solution was the transistor. Instead of electrodes,
it uses a semiconductor, like silicon treated
with different elements to create an electron-emitting N-type, and an electron absorbing P-type. These are arranged in three
alternating layers with a terminal at each. The emitter, the base, and the collector. In this typical NPN transistor, due to certain phenomena
at the P-N interface, a special region called a P-N junction
forms between the emitter and base. It only conducts electricity when a voltage exceeding
a certain threshold is applied. Otherwise, it remains switched off. In this way, small variations
in the input voltage can be used to quickly switch between
high and low-output currents. The advantage of the transistor lies
in its efficiency and compactness. Because they don’t require heating,
they’re more durable and use less power. ENIAC’s functionality can now be surpassed
by a single fingernail-sized microchip containing billions of transistors. At trillions of calculations per second, today’s computers may seem like
they’re performing miracles, but underneath it all, each individual operation is still
as simple as the flick of a switch.

100 thoughts to “How transistors work – Gokul J. Krishnan”

  1. To fans of Fallout games, Fallout is set in an alternate earth that has never invented the transistor. They only use vacuum tubes, which is why computers were huge.

  2. i didnt know logic circuits are made of transistor… :/ and i also i didnt know each gate AND OR has thier own name haha. thanks ted ed now i know ๐Ÿ™‚

  3. The HIGH and LOW voltages thing is a bit misleading here. Yes, 1 is typically a high signal and 0 a low one, but it depends if the system is active HIGH or active LOW. In other words, 0 can be HIGH and vice versa. Additionally, LOW is very rarely represented by a voltage of 0 as how does one know if the machine is working if there is no voltage? It is doing the same thing it is doing as if it is off. As such, LOW is usually a voltage of 1V, 2V, or some other lower voltage (or, again, HIGH can be represented this way as long as you are consistent.) You just need a difference in voltage for the system to work. Just a fun fact for everyone. ๐Ÿ™‚

  4. So when a charge passes through a transistor this can be determined as a 0 or a 1 creating binary; but what is actually controlling the voltage? How is it turned on or off?

  5. i studied it in electrical engineering for about 4 years total. And now they compressed it into 4.53 minutes video, amazing LoL

  6. Didn't you miss the part at 3:50 to 4:10, you comfortably skipped the logic behind the switching. And the animation is inaccurate, as it showing the electrons being stopped at the base emitter junction and not the base collector junction. Sorry but what my books told me was the base and emitter in this configuration are always forward biased. Please correct me if I had made a mistake(Regardless the animation is outstanding).

  7. This was the one device that was never invented in the fallout universe… If memory serves, No pun intended

  8. 1: bassiccally transister are made of : zinc & copper & silicon = 3 diferent tiny plates ! Which plates doing what & power volt? Right dude?

  9. As a person who is currently studying Analogue Electronic and Digital Electronics , your animation and information on how Transistors work is 10x better than what my college teaches us . Hope you could expand more into this topic !

  10. PLEASE MAKE MORE VIDEOS LIKE THIS , about computers , networking, storage , etc. You guys are awesome!!!!!

  11. ANSWER!
    idk just pls dont burn my amplifier ๐Ÿ™
    01101001 01100100 01101011 00100000 01101010 01110101 01110011 01110100 00100000 01110000 01101100 01110011 00100000 01100100 01101111 01101110 01110100 00100000 01100010 01110101 01110010 01101110 00100000 01101101 01111001 00100000 01100001 01101101 01110000 01101100 01101001 01100110 01101001 01100101 01110010 00100000 00111010 00101000

  12. The most important thing i learned from this video is some transistors are friendly and wave to you when viewed under a microscope.

  13. I have a feeling computers will evolve to processing in temperature variations, measuring fractions of trillionths of a degree instead of mass raw voltage alone. Ex. Water (or some liquid) that freezes at X rate with Y pattern produces Z code with E sequence. Liquid quantum computing. Less thermal breakdown if the liquid medium is developed to remain thermostatic at a broad range of ambient temperature. Salt water is already conductive and who knows, maby the byproduct of computing produces hydrogen fuel to power itself.. The answers are probably over complicated. Aliens man, aliens..

  14. Right Iโ€™ve been stuck on this for ages now. Iโ€™ve done my research and still havenโ€™t found an answer. How does a computer alter the voltage to a transistor, because surely it must switch between a high and low voltage constantly to change the output of a transistor?

  15. learn english easily ุชุนู„ู… ุงู„ุงู†ุฌู„ูŠุฒูŠุฉ ุจุณู‡ูˆู„ุฉ says:

    Those vedios are great and helpful

  16. TED without stage โ€žperformanceโ€œ is an advancement. However the hooked on background โ€žmusicโ€œ disturbs and distracts from listening more, than the soundmixer/producer could ever imagine. The soundtrack does not contribute content, it simply spoils the content. Pls delete that track if possible and reupload. Thanks for the vid.

  17. There are a lot of questions in my imagination and I need someone to answer me about them We in Yemen live a lot of loss and most of us live in an illusion They do not know about science Thank you for the programs you offer for the truth seekers Thank you thank you

  18. Loved the video. Wouldve been nice if you included some history behind these inventions, like the name of the inventors!

  19. please make a vedio on

  20. Sometimes I feel learning science is very much important. People who choose commerce or humanities are never going to know how this world works. From quantum physics , astronomy, computer programming, engineering, hardware, chemistry, mathematics, bio technology, …. everything is done in science.

  21. The treating of silicon with other elements to create an electron emitting N-type and an electron absorbing P-type is know as doping. It's used to create conductance. Since the outer shell of silicon is 4 valence electrons, it's easy to fill silicon's outer shell with other silicon atoms. This makes conductance hard. So, some silicon atoms are replaced.

  22. Sooo, millions of transistors are shouting either yes or no. How does that make my computer process something??

  23. If your computer is ticking then theres probably something foreign in your fans. Or you have very loud harddrives

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