Making logic gates from transistors

[@roryhemmings7860]

the best thing about this guys videos is that he dosent waste time at the begining of the video, he just gets right into it

[@BillAnt]

Gosh I hate those fancy intro graphics a lot of KZbinrs are using nowadays... Ben just cuts to the chase, it's like a delicious ice cream cone without a stupid wrapper. :)

[@muhammadosama3358]

Exactly.

[@jetlinux]

The best thing is his explanations that make it fun and easy, but yeah, love that he doesn't waste time.

[@efai]

@@BillAnt ​ Gary Ford yeah, he really doesn't waste the time, except he did (7:38 - 8:17), that looks like wasting time to me and explaniation of "XOR" was kinda bad..

[@BillAnt]

@Efai < Well that minute was obviously an editing mistake (or maybe intentional to give us time to grab a snack;), should have deleted it from the final cut. But it's all good in the Ben Eater hood. ;D

[@mutalibgozalov7208]

0:00 - basic transistor 2:25 - inverter 4:14 - and gate 6:08 - or gate 7:38 - *NO* gate😀 8:29 - xor gate 11:50 - whole list

[@rituchandra6325]

7:38 NO gate lol XD

[@mathewtallen3190]

Yes 7.38 no answer

[@HelloKittyFanMan.]

What about Watergate, Inflategate, and Bendgate?

[@suryanshdaspatnaik3474]

@@HelloKittyFanMan. XD

[@ash7324]

NO!!!!!!! >:@

[@can_uysal]

that unedited part at 7:38, pure chill.

[@gongal6]

Is like when the teaches ends his explanation, and waits for the students to copy what are in the board

[@bertkutoob]

@@gongal6 Or for you to do a screen grab...

[@firmman4505]

?

[@VerticalWit]

[@purboyy]

He was grabbing something

[@cfopeter102]

Discovering your channel is the best thing that has happened to me in a long time. As an EE student who just got started on learning basic digital logic and circuit design, this has my mind blown. Thank you for your videos!

[@aedanyates2612]

Your paper moving skills are off the chart

[@glitch349]

69 likes... nice

[@dramforever]

Probably just moved the chart

[@HelloKittyFanMan.]

@@glitch349: No more, heh....

[@johnwick5901]

It's actually on the Chart.

[@HelloKittyFanMan.]

HA, @@johnwick5901!

[@bertkutoob]

And that, my friends, is how computers work! Now that I know this, my next challenge is how to get 1,5 billion transistors into a cellphone... Could be a bit tricky.... Jokes aside, as a retired Civil Engineer dabbling for the first time in electronics as a new hobby, this video and style of teaching cannot be overpraised. Well done Sir! Much appreciated!

[@kerem54545454]

bertkutoob my challenge is how computer monitor is able to show us the output on the screen

[@radeklew1]

@@kerem54545454 Good news! This channel has two videos in which he makes a graphics card!

[@jeffreyogodogun285]

Yes. Now it's time to figure out how billions of transistors in smartphones work!

[@ms-dosguy6630]

@@jeffreyogodogun285 Its called integrated circuits

[@bertkutoob]

@Joe Black That, I understand is how it's done... Clever people, these computer scientists...

[@higigls]

Till date the best explanation of logic gates using transistors. I wish I had got this 18 years back

[@HelloKittyFanMan.]

Yeah, not even ITT Tech taught me this! It would've been nice! My parents blew about $20K on that joint!

[@MarkusBurrer]

18? 30 years

[@brudamonas8208]

There’s a video that explains it very well too, i think the channel is called “the organic chemistry tutor”

[@knight-errantservices1121]

I did forty years ago from McGraw-Hill. Serendipity: I got into Ben's videos looking to recreate that logic-gates-from-transistors experience.

[@justinjames3028]

@@MarkusBurrer I was about 30 years ago too. Had a professor who was probably a great engineer but not a good teacher. He often said partial credit is why the space shuttle blew up and the Hubble telescope didn't work at first. He would also stare down any student who walked in late to the point where if you thought you were going to be a minute late you would just skip. Crazy the difference between a guy like that and someone who actually motivated the students to learn.

[@NineInchFailz]

dude your videos are perfect. You show the schematics, boolean truth tables, and physical breadboards to prove it all right there.

[@moiquiregardevideo]

Resistors used on base: 1k Resistors used on collectors: 100 ohm Transistor model:2N2222 Led: green at 1.2 volt You can use white led at 3 volt The modern silicium transistors have an incredible dynamic range. When OFF, the collector/emittor appear like a very high resistor of more than 50 Meg ohm. When ON, the same two pins act like a low value resistor of about 0.1 ohm. The expression 'semi conductor" is misleading. The material conduct as good as the best metal, copper, in the ON state and act as an excellent insulator when off. The first transistor made with germanium were not as good. In the off state, there was a current leaking from collector to emitter equivalent to about 10 k. When the transistor was warm, it leaked like if it was a 1 K resistor. The OFF state was not that strong neither, cold or hot. About the NOT gate: The explanation is as follow: When the transistor conduct, it is able to act like a very low shunt resistor of approximately 0.1 ohm. It can force the voltage to go as low as 0.2 volt, which is much lower than the usual voltage drop of a diode, 0.7 volt. If you take a voltmeter, you will measure: Emitter = 0 volt Base = 0.7 volt Collector = 0.2 volt The base/emitter pins of a transistor are simply a diode with the usual voltge drop of 0.7 volt. A green LED need about 1.0 volt to turn ON. If you apply 0.8 volt, you get no light at all, not even a feint glow. So, since the transistor can lower the voltage to 0.2 volt, the LED is off. However, if you replaced the LED by an incandescent light bulb, you would see a feint red glow when the logic state is "0".

[@jacksonmandle4774]

Thanks

[@BillAnt]

It should work just fine even with +/- 10% variations, the tolerances are not super critical.

[@connorwatson7162]

Is it safe to leave a transistor (im using a mosfet) active for a long period of time?

[@Pedritox0953]

Best explanation so far... is better wwy see semiconductors lke dynamic or active resistane than the usual way

[@istvanszabo5745]

The 0 level in a logic circuit is actually not 0 Volts, just close to it.

[@TheDJRiffin]

I loved the silence around 8 minutes. It felt as though he was giving us time for it to sink in. Brilliant!

[@lucaguitarplayer]

If you are still not a professor please... Became It! Best lesson of transistor i ever heard!

[@simong1666]

I love these videos. Ben has a special talent for being able to speak very quick and clearly at the same time. It's like speed reading interesting content

[@koolv6210]

13min- see the diagram & circuit connection is same? Diagram & circuit connection same? Diagram looks like incomplete 😅

[@masterkamen371]

​@@koolv6210I don't see how any of the shown diagrams are incomplete?

[@susiesan]

I took a computer hardware architecture class in college and we briefly discussed and/or/not gates which I kinda got - your explanation totally cleared it up for me. I definitely had an A-HA! moment watching this video.

[@LogikalMindset]

15 years experience as a control systems engineer ( specifically PLC's)and now I finally get it ...Ty!!!

[@TheLeAlan]

Finally a video where I could clearly understand what transistors actually do and why are they so important. Thank you!

[@lookupverazhou8599]

I didn't know they were just switches until a few days ago. My mind blew clear open. Boolean logic in a miniature device simply would never have existed if it weren't for these things.

[@herrbonk3635]

@@lookupverazhou8599 They aren't switches really. Physically, bipolar transistors are continous (exponential) current amplifiers. Using them as binary non mechanical on/off switches is just a special case abstraction. Their primary usage were/are in various forms of (often audio) amplifiers, oscillators, comparators, etc. Such as for radio receivers, tape recorders, TVs, instrumentation, and so forth.

[@lookupverazhou8599]

@@herrbonk3635 Why do they amplify, but an additional junction doesn't?

[@herrbonk3635]

@@lookupverazhou8599 Additional junction? A transistor has two junctions, the base-emitter and base-collector. It is like two diodes with a common anode or cathode (pnp or npn). In these bipolar transistors the amplification is a result of a pretty complex interaction between minority versus majority charge carriers (holes and electrons) forming and drifting in (and due to) the electric fields applied. Hence the name, bipolar. It's easier to explain a field effect transistor though, because it works very much in analogy with an electron tube. By applying a voltage at the gate, the resulting electric field forms a thin region (more or less) depleted of carriers. This adjust the amount of current that can flow from source to drain at a certain source-drain voltage. So a field effect transistor is more like a voltage controlled resistance, while a bipolar transistor acts more like a current source or "generator", controlled by a much smaller base-current.

[@mikeshane2048]

I wonder why isn't this channel popular, This channel deserve more than this

[@dg-hughes]

Rename it SuperZap or some fancy name so people can brag about watching the SuperZap channel.

[@bitterlemonboy]

Anything in universe has what it deserves. Maybe he has to work a little bit harder? Stop making stupid comments like this. Everything has what it deserves. It's called Natural Equality.

[@fadithedog]

FurkanSE are you dumb?

[@rzul]

@@fadithedog are you dumb?

[@rzul]

@@littlerussianmax5831 Congrats, you're starting to grasp it

[@stuffoflardohfortheloveof]

Just came across this vid by complete accident. Absolutely brilliant. I’m in my 50’s now and learnt logic gates almost 40yrs ago during computer studies BUT was never shown how to use them in practise with electronics so I never made the connection between 0 and 5v etc. Electronics ended up as a bit of a dead end subject for me and I went in a completely different occupational direction. I’m now retired and really enjoying getting back into electronics and have thought about trying to work these logic gates out for myself. You’ve not only beaten me to it but explained it really well. Thanks very much! 👍🙂🏴󠁧󠁢󠁷󠁬󠁳󠁿

[@MamoonSyed]

This is the simplest and most intuitive explanation of a transistor I have ever seen. Very good work.

[@VirginiaGreco_Scrapbooking]

I studied all this at the University (I am an electronic engineer), but I am still really enjoying watching these videos of yours because you explain very clearly. Better than many of my professors of the times. Congrats! :)

[@taipo101]

Totally agree. Got my electronics degree in 1975 Bolton UK. This guy is so chilled unbelievably makes everything super simple and excellent voice too

[@wajideus4591]

For those who are interested, his explanation of how a transistor works is based on conventional current; which is the reverse of the actual electron current. You can imagine the electrons building up on the emitter with nowhere to go because of the depletion zone between the emitter and collector. when the circuit between the base and the positive terminal of the power source is closed, the electrons move from the emitter through the base to the positive terminal and in the process are also able to cross the depletion zone to the collector.

[@HaloWolf102]

Everything up till this video, we covered in my Digital Electronics class, but this is something that was NOT covered, and it a very important in understanding how all the gates work. PLTW has failed me as a student, or the teacher did not follow the course right. Either way, it's taken me 5 years to finally learn the truth on how these work. Thank you education system, you sure did me a great service.

[@ms-dosguy6630]

That's is quite unheard of. Surprised they *didn't* go over this.

[@mohammedal-alaw6249]

this is actually called RTL logic it was shortly replaced by TTL gates because of the high current consumption!

[@moiquiregardevideo]

Actually, the main problem of RTL is low signal. Each time a binary value defined as binary 0 for 0 volt and binary 1 for 5 volt go thru a RTL chip, the designer need to recondition the output with external amplification. TTL simply add transistors on the chip, thus making the output as strong as the input.

[@orppranator5230]

Christian Gingras So, semantics?

[@a-rod6336]

@@orppranator5230 Yep, meaning matters. Shocking stuff.

[@supernova5434]

And then being replaced by CMOS eventually

[@ArneChristianRosenfeldt]

Looks more like transistors, resistor logic to me because the inputs are not connected to a resistor. Also in an IC a resistor is much more expensive than a diode or even a transistor.

[@scoopasoop6052]

I love how consice he is, his understanding, and his presentation, is this guy a professional teacher or something?

[@southernkatrina8161]

He used to make videos and write math exercises for Khan academy. There's a vid of him being interviewed about it.

[@absurd_derpeta1993]

6 years late, but this video really helped me understand how transistors work in logic gates! Thank you so much :)

[@darrylbartlett2713]

In the military I worked on 60's era launch control system. All of the logic was built like this on postage stamp sized boards.

[@cesarrodriguez-tw9bp]

I've seen only two of your videos, and it feels like a complete ILLUMINATION !! Now I understand how logic gates are made with transistors, the way they look physically, and how they are inside the DIP IC's ... thank you SO much. I had lost the interest on the subject but it rose again now that I'm watching your videos because now I understand. Your videos are clean, brief, on point and very detailed. THANK God you are making these videos! YOU HAVE the talent of teaching, God BLESS YOU MAN!! for real!!

[@farziverse4209]

This was really brilliant and simple. I am thankful, guys like you are on the internet

[@JacobPlays136]

I’ve been trying to understand transistors and logic gates for months. This video just did it in 13 minutes. Great video!

[@Replied_ByMeatr1der5]

You sir are my saviour. Finally someone EXPLAINED how this thing really works instead of giving me false, useless and over"simplified" examples of how the gates work

[@JohnVance]

I don’t have the cash or time right now, but I’m going to buy and build all of your kits, this is addicting

[@Enderbro3300]

Not to take away from him but you can also just like, buy a pack of 100 transistors off Amazon for like 5 bucks. But then you also need the breadboard and wires etc which I'm sure his kit has. But if you wanna expand electronics is one of the cheapest hobbies I have XD

[@adbrooks95]

Roughly $45 and you can get an Elegoo kit with a breadboard, arduino uno r3 and components and jumpers including a couple transistors. I just got one and it's great so far!

[@lookupverazhou8599]

​@@Enderbro3300 I just spend over $400 on a bunch of electronics stuff, huhu.

[@robertwilsoniii2048]

What makes this so dope is you include both analogue and digital circuits at the same time for a complete picture of how everything works with no deception or gaslighting involved. Often digital logic is taught by saying 'you don't need to know the implementation' or 'it's not my job to explain analogue circuits.' And analogue circuits are taught by saying 'it's not my job to build logic gates, it's to show the science of transistors.' etc. So people end up with a huge hole in understanding that is exactly this video. You do it the right way, providing the analogue circuit as the primary foundation with its truth table as a tertiary feature.

[@sevfx]

You got a pretty long silent part from 7:40 - 8:17 I think you forgot to make a cut ;)

[@pyromen321]

Severin I was laughing through that whole goofy section

[@mattshu]

I came to comment the same thing :P It really broke the fourth wall for half a minute

[@draco5991rep]

It was kinda akward and unsettling :'D

[@GoatOfTheWoods]

i actually liked it, it's like listening to a teacher who at some moment browses his files to look for what to talk about next

[@nicolasnicolas5238]

I liked it too, I felt it was some kind of asmr

[@amatoriorupertleiman4154]

I just learned what a basic transistor is in just 2 minutes, like veryyyyyy clear and concise, compared to when I was in out online class.

[@TheDeepshock]

I have to leave a comment here. I have been looking for an intuitive explanation on how XOR gate works at circuit level for very long time as I have not electronics background. I finally get it today. The sense of understanding is great. Thank you Ben.

[@Pozydrive]

THANK GOD, I FINALLY GET IT! I've been trying to learn this for a few months already, you showing the schematics as well as demonstrating it made it click for me!

[@kworgz]

Just watched many intro to logic gate videos.....Logic concepts are as simple as they can be but their purpose didn't click until I saw a physical representation of them like you've done here. Thank you!

[@basztarek]

So far this is the best video explaining logic gates. I appreciate the explanation, the schematics, as well as that you have the gates built on a breadboard, so the users can pause the video and try to rebuild it by themselves. Thank you! EDIT: I think you had something wrong with the OR gate, mine didn't work that smooth, didn't know why. I worked it over with another video and it works though. While these gates are good for demonstration purposes, the wiring could be optimized by linking the transistors without jumpers.

[@muhammadamirkhan3779]

Excellent presentation/demonstration to easily understand logic gates

[@herbertotto4725]

About 50 years ago - Vietnam War era. We had several books of circuit diagrams and others with logic diagrams built with basic gates like these. Hawk Missile guidance control systems. All "Top Secret" back then. It would all fit on a grain of sand now. But back then it was big stuff - actually useful when we could keep it running. Lots of breakdowns. That's where I came in. (smile). After service, I used to keep a small breadboard of logic circuits on my desk to remind me of those times. I'm 75 years old now - still breathing.

[@EmptyGlass99]

By far the best explanation of how transistors work I've ever seen. I wish I could 'like' it more than once. The XOR gate in particular was a eureka moment for me. Thank you.

[@0MoTheG]

He never did explain how a transistor works.

[@EriAirlangga]

Finally, a minimal TTL diagram that really works! Thank you!

[@0MoTheG]

There was no TTL in the entire video.

[@silviam.7195]

This is RTL - Logic. :-) Because there no Multi-base Transistor in use...but the gates working nice using a normal light bulb and the npn Transistors 2N3055 to realize the switches, because more current in flowing through collector-emitter circuits.

[@gman76utube]

WTF is everyone talking about, TTL and RTL were logic gates from the 1970’s and 80’s. Virtually all logic gates produced today are CMOS which is much simpler to explain than bipolar transistors.

[@ArneChristianRosenfeldt]

@@gman76utubethe symbols in the video are for bipolar transistor, not MOS

[@ArneChristianRosenfeldt]

@@silviam.7195doesn’t TTL use multi-emitter. Each input goes through a common base amplifier. Common only means that the lead of the transistor is connected to a common wire. The semiconductor does not need to connect them in a monolithic fashion ( like the base connects emitter and collector ).

[@guyconiglio8223]

I've been looking for someone to explain these gates forever - this is so helpful.

[@DELLISTX]

I don't think you know just how GOOD this video is, as I been thinking about all the circuits I could do, and I can just see it.It was just an excellent way to teach it. I have been thinking about this for hours. I am very good at electronics and you just did a super job. You could change some kids life, by just waking them up, making them think, opening a whole new world! WELL DONE!!

[@aashiqurrahman329]

First time I understand the logic gate, I used to memorise all the value in my college😢. Thanks to you man❤

[@michaelthebeast6555]

He’s so good at explaining I’m only 11 and I understand

[@randomgamer3964]

Yh

[@dictator7586]

Nice

[@willyeckerslike9437]

Great

[@nonagone9570]

Amazing

[@minecraftherobrine1234]

@@nonagone9570 I'm 8 and I understand Redstone

[@johndeluca230]

Flashback to building these in an undergrad Computer Logic course I attended back in 1985... Thanks for sharing! I enjoyed it!

[@jyotiraina7682]

Your video is just amazing. The explaination so crystal clear. Thanks as it helped me built my physics project on logic gates.

[@Engineer9736]

I don’t think electronics is the same study as physics. Physics is about the behavior of physical matter. Electronics is a complete different area.

[@prezadent1]

@@Engineer9736 Shut yo' mouth foo'

[@Jupiter__001_]

@@Engineer9736 Wrong. Electronics is a subset of physics, and originates from physics. We had to study electronics as a part of the electricity topics in physics all through secondary school.

[@davidrosset4457]

I was finally able to make the XOR gate through your video. Such an elegant design. Thank you.

[@bakshiism]

I barely turned 13 years old and this really helped me clear things on how to make gates and what the hell a transistor is. Thank you so much. please continue this work

[@bakshiism]

I also am making a binary calculator with this, if you can, please look into how I can use this to make one.

[@DefaultFlame]

@@bakshiism Watch his homemade 8-bit breadboard computer series, specifically the parts on the ALU (arithmetic logic unit) and the registers. Actually, I'd suggest just watching all of it, because it's great, and then the rest of his videos. He's the perfect teacher when it comes to low-level computer engineering.

[@scott7695]

I wish you taught me my first year of electrical engineering school 🙂 So much time spent working formulas calculating all kinds of stuff and zero time spent just telling you how the components work and what you could do with them....love the practical explanation!

[@matchileon6102]

This is more helpful than my stupid college lecture.

[@jayc8040]

I’m in my 3rd year as an electronic engineer student. Your videos are so helpful and you make it so much easier to understand. Thanks you!

[@schmetterling4477]

In other words... you are lying about your education. ;-)

[@Chris-jd9wg]

@@schmetterling4477 “The secret of education lies in respecting the pupil. It is not for you to choose what he shall know, what he shall do. It is chosen and foreordained and he only holds the key to his own secret.”

[@schmetterling4477]

@@Chris-jd9wg Dude, I knew these things when I was twelve years old. If he is in his 3rd year and doesn't, then he is studying cosmetology and not electrical engineering. ;-)

[@Chris-jd9wg]

@@schmetterling4477 Wow! At twelve? I don't know how old you are, but even if you're only in your 20s I can't imagine what you probably know now! Believe it or not, a lot of people in their second, third, and even fourth years studying electrical engineering don't get a solid grasp of the material. It is SO dry. The textbooks were mostly all written in the 70s; it is utterly brutal to try and keep up with it, especially if you don't have a good instructor. The best electrical engineers I have worked with have almost universally learned electronics at a VERY young age (like you). Some people just get it, while others struggle badly. This Ben Eater guy explains things so well that you almost feel stupid after watching his videos. I would rethink my life if I was studying electrical engineering.

[@schmetterling4477]

@@Chris-jd9wg Today I am old and I know how to build large particle physics detectors. So do thousands of other people. Big deal. What I don't do is to pretend that I know how to coach American football, which is what the majority of folks on the internet are doing in one form or another. I know what they teach in EE. I have been sitting in some of those lectures when I was a student. But here is the deal: you are not restricted in university to learn only whatever material the professor presents. You can know more, way more and way, way more. If you haven't surpassed this level of material in your third year in EE, then you simply don't belong in the field. Electronics is exceedingly easy to learn as a teenager. That's how I learned it. I may not have known 4-pole theory but I sure as heck could build working circuits, both digital and analog. I even had the data path of a 64 bit CPU design in TTL running at 32MHz on breadboards by the time I finished high school. I never finished the instruction set and the microcode sequencer, though. I didn't have the necessary books on computer science to understand that level of architecture. After that I had to serve in the military and I began studying physics, so I lost interest in these things. All I am saying is that this here is not third year EE. It's kindergarten electronics.

[@jamesarmstrong3000]

I had a difficult time with transistors, cuz I'm a beginner. After watching your video, I have at least vaguely understood them.

[@aidanc4719]

learn.sparkfun.com/tutorials/transistors/all I found this article really helpful :)

[@ricj9594]

@@aidanc4719 thnak you! hugs from são paulo, brazil

[@yaroslavpanych2067]

Speaking the truth, he showed only half of functionality transistors provide - their saturated and cut-off states. Primarily transistors are current amplification devices, and cutoff and saturated are just edge-cases of that process. "Funny" part comes when we stop talking about DC and start talking about AC and here we meet several more dozens of characteristics diagrams for transistors.

[@dahlavibez5726]

Master Ben, your a true guru in these videos man, I'm able to expand my projects after your straight forward teachings . Bless you sir

[@Thereadingmusiclover]

I'm pretty sure that I've learned more from you about electronics than both my electronics and microprocessor class in college combined! You're very good at explaining how it all works! Keep it up!

[@kotachan6784]

I'm 19 now.. A medical student, but Always had curiosity for circuits, processing, computing and transmission of information.. Gosh, electronics left me awestruck! Back then KZbin wasn't how like it's now.. Not to mention I got my mobile phone last year. When I was a kid, I never had the proper exposure regarding these things, as I'll be the first member for my family to receive a degree. I think, it's not too late to explore the field

[@JimKinkade]

Thank you. I'm using this information to totally rewire my computer.

[@Calvinatorzcraft]

That's nearly impossible

[@FutureAIDev2015]

😮 You have WAY more patience than me!

[@abdelrahmangamalmahdy]

Jimmy Kinkade LMAO You gotta have an electron microscope to get to see the inner wiring of your CPU

[@KuraIthys]

You're working on the assumption that he's talking about an off the shelf computer that consists mostly of Integrated circuits. If he means a homemade computer created using discrete logic or any of a number of techniques to create custom circuitry (many of which are described on this channel) then it's a perfectly reasonable thing to do. You can make your own CPU using anything from transistors, to logic gate IC's to memory chips (memory can replicate any function it has enough pins for. Something with 8 data lines and 8 address lines can replicate any discrete logic function that has 8 inputs and 8 outputs. You can even theoretically build an entire processor using this alone.), and of course you could use an FPGA if you need very high performance and complexity and something that's practical for frequent use. Did you know the Amiga's custom chipset was made in prototype form using discrete logic and stuff like this? A bunch of massive circuit boards full of components, which in the final thing reduces to just 3 integrated circuits. Nevertheless the prototype was made of discrete components, and it worked the same as the final thing, though it was more failure prone.

[@abdelrahmangamalmahdy]

KuraIthys, with respect.. nobody makes a computer using discrete transistors, it would take thousands of transistors to make a simple 8 bit computer.. also, how can you expect this video is helpful for someone who has already made a homemade computer with discrete transistors !!

[@normantyson5314]

It is fairly easy to design circuits w/ logic gates, but it is interesting to see simple designs that are necessary to build your own logic. All are straight forward until reaching the exclusive or gate. Left on my own, I would have a working design w/ 7 transistors, but your clever design does it in 5. Again, you are the master.

[@swedensy]

Second schematic uses voltage devider. There is still voltage across diode, just not enough to light shit up.

[@derikbates961]

Thank you for explaining this. I was wondering why it "wasn't" getting voltage.

[@boyuan588]

This is a good point. I think the video made a misleading post by that the circuit is not complete when both A/B is on but this is actually not the case

[@slzckboy]

Being qualified to teach and actually being good at it are twi different things. This guys get a logic high of both inputs of that particular AND gate.

[@variopancolar6487]

I think he didn't even understand what a logic gate is. Thats why he sells us the schematic of an NAND Gate as an AND Gate.

[@axeldaguerre8838]

What you do is exactly what i want to learn, i will definitely pay on patreon if i see you are consistent (it is my first video from you)

[@xqqqme]

Almost 5 years after this video was uploaded I stumble upon it during the process of trying to learn about transistors, microprocessors and how computers work...and this video manages to get this basic gate info across to me even better than the fabled book "But How Do It Know?" which had me glassy-eyed by page 36! Well done, sir!

[@ThatGuyDownInThe]

my mind is truly blown on so many levels. Man I love this stuff so much.

[@beno2782]

What i didn't get in school in several hours, I get it here in few minutes, thank you very much! 😊

[@FutureAIDev2015]

I have an idea for the XOR gate. To save power, you should put a transistor in series with the two transistors that basically make a NAND gate. Then, connect the base of that transistor directly to both inputs. This ensures that if A or B is on, the circuit is on, but if neither A nor B is on, no current flows at all.

[@FutureAIDev2015]

Put the transistor mentioned before between the positive rail and the first transistor of the NAND gate.

[@FutureAIDev2015]

+Matthew Ferrie Before the resistor.

[@andrewrobertson1473]

My apologies for responding to a two-year-old comment, but for anyone reading this now: Tying both inputs to the base of a transistor would not work as you've now shorted the two inputs in question. If the inputs are driven by opposing logic levels (ie, one high and one low), you've short-circuited 5V, and the circuit could get very hot very fast. Or just cause your microcontroller to force shutdown to avoid cooking itself. In general, I wouldn't recommend it.

[@johneagle4384]

Thank you. For a newbie like me, these videos are gold.

[@mannycalavera121]

I loved electronics as a child, I was always disassembling broken electronic for components, making things, but never had mentor or support and this was pre internet (too poor to buy a computer anyway) pre maker space days so outside local library I was out of luck. Now as an adult with young children of my own I'm picking back up these hobbies in the hopes that if my son's so choose, I can perhaps help them I whatever interests of endeavours they choose. Guess thats my long winded way of thanks for making these videos.

[@erobertt3]

It's so amazing to me to think that this thing that I'm typing on right now and sending to thousands of people is all working based on these basic circuits. Humans really are capable of incredible things.

[@dowskivisionmagicaloracle8593]

Incredible! This is the knowledge gap I've had when it comes to ICT.

[@nealmaxwell790]

Taking both Intro to Semiconductors and Logic Systems, and this one video taught me more than both of those classes. Higher education at its finest people!!!!

[@privatefactory1173]

One of the best videos on the web. But I keep wondering why everybody in every video and tutorial keeps repeating that when transistor is on all the all current flows through it and because of that the potential difference between collector and emitter drops to 0, effectively meaning that both of LED's legs are connected to positive side. That's not correct, transistor is not a superconductor, it still has a resistance when it's on, current does still flow through LED, the reason why LED turns off is because current becomes way way too small which is not enough to light up the LED.

[@southernkatrina8161]

It needs 0.7v to light up.

[@derikbates961]

Thank you for explaining this. I was wondering why it "wasn't" getting voltage.

[@english_albanian_translator]

Amazing explanations! If you are a professor, your students must thank God every day to have you as their professor.

[@srduke]

It was at that moment that I actually learned how a computer really works!

[@Magneto994]

Thas was an excelet explanation --Thanks a bunch!!! I'm a venezuelan guy very intersted in electronic issues because right now i'm working in repairing electrical devices such as whashing machine, refrigerator but the problem is i dont have as much knowledment in electronic topic as to solve most of the problems. thanks again for your channel.

[@burakerdem9758]

Hello, thanks for the video. I have a question in mind about the circuit at 3:20. So, we're saying that there is no voltage difference between the two sides of the transistor, and I guess that's because the resistance of the transistor is negligibly small. But does electricity still flow through the LED, albeit with no effect visible such as light? And does that, in a larger scale like in CPUs where there are many transistors, affect the system?

[@burnstick1380]

Electricity always flows, even when a transistor is turned off. But the voltage and amps are so minimal that they are neglect-able. Most processor or logic devices have a minimum voltage threshold (before they activate). This is good because it smoothes out minor leakage and reduces the risp of EMI (electromagnetic interference)

[@sakshamchhatkuli271]

Best explanation in this whole world. Superb teaching skills.

[@Zahlenteufel1]

his videos are so low-tech but so good

[@mericet39]

I wasn't much good at electronics at school. If I'd had Ben Eater as a teacher, things might have been very different.

[@Kylefassbinderful]

What I've noticed in the XOR gate diagram that you made is that it's two gates that work together. An OR gate and an AND gate. The OR gate is the primary gate while the AND gate is more of a secondary. The AND gate just adds more functionality to the OR gate.

[@Quizzingisfun]

I was laying in bed, thinking about precisely this, and i find it on my raccomandation 5 minutes after. Damn

[@100vg]

Excellent on building Logic Gates with NPN BJTs. Very clear and precise. Thank you!

[@hercion]

A minimal transistor-count Toggle Flip Flop would be very interesting !

[@isaaxrohret7027]

This is probably the best video out on KZbin, like a soon as I wanted it, I got it. Many thanks, my friend.

[@risingmermo]

duuuuuudeeeee, i was stuck for sooooo long on the very first circuit. (literallly for like 2 hours).turns out i had the transistor the wrong way round

[@georgemorgan8683]

Best explanation of how to use transistors to make logic gates on KZbin.

[@sempiedram]

Super noob question here: at 4:13 why does current "choose" to flow through the transistor instead of the LED?, is it because the LED has a slightly higher resistance?

[@mahmoudm451]

That's my question too. I don't think it's a super noob question.

[@DevinDTV]

Even if the LED had high resistance, I don't see how the current through it would be reduced by turning on the transistor. In a parallel circuit, the voltage through all resistors is equal. So the voltage through the transistor and LED should both be the same. All adding the transistor does is allow for more current to go through in total.. it shouldn't have any effect on the LED. If you do the math on a set of parallel resistors you'll see what I mean. PS: From what I've read online, an LED has a resistance of about 12 ohms and the emittor part of a transistor has a resistance of about 6 ohms. Do the math on parallel resistors and you'll see that it doesn't matter if the transistor is on or off. LED should have the same current and voltage in either case.

[@DevinDTV]

In other words, I have no fucking clue why the LED is turning off at 3:30

[@sempiedram]

haha ok, thanks anyway

[@sempiedram]

Your comment was deleted as spam (not by me). I suppose it's because you posted a tinyurl... But thank you for the diagrams in there. They actually made it easier to understand (and tinker with) the circuit.

[@iteachtime]

Super video! I applauded for $2.00 👏

[@hheg2727]

Why do you need the middle voltage supply in the XOR-gate?

[@mistersir3020]

I'd like to know this as well.

[@0000TM0000]

Yeah. This doesn't look quite right.

[@Tuxfanturnip]

I think it's to pull the middle voltage up to high when it's not connected from the right, preventing residual voltages from messing with the output

[@Isclachau]

I’m still wondering this, why doesn’t the voltage go straight to ground through transistor if it’s always on as he says in video?

[@jihadsamarji]

Please Someone Answer To This !

[@andreasg7543]

Super Video! Ich habe für 5,00 € Applaus gesendet. 👏👏

[@MarkRMichaels]

The part at around 3:45 about differentials is a little confusing to an amateur. It seems like a current would be flowing through both paths and the light would still be on. Maybe that could be clarified better? Great video nonetheless. Thank you!

[@1280-user]

perhaps it's a matter of resistance. if transistor's resistance is too small compared to led's resistance then almost no electricity will move through the led

[@1280-user]

kaliKoder yes you can, just make sure that the resistance in transistor's path will be still too small 'Compared' to the led's one.

[@linuxBlob]

You can think of a transistor as kind of splitting a circuit in two. One side on the collector side and one side on the emitter side. Voltage is the difference between two points. When the button isn't pushed, on the collector side, with respect to ground is +5V (minus some for resistance), that is because there is no flow on the emitter side. When the button is pressed, there is flow from the collector to the emitter. Thus the energy is on both sides of the transistor. Since there is no *difference* between the collector side and the emitter side, the point on the collector side leading to the LED is 0V with respect to ground. You are correct in thinking that it looks like a parallel circuit, but because of the transistor, you don't actually have a parallel circuit, you instead have the part of the circuit on the collector side of the transistor and the side of the circuit on the collector side of the transistor. You can try this yourself, if you build the circuit as shown and then measure the anode side of the LED vs ground (or negative on your battery), you will measure zero volts. If you measure the emitter and collector sides of the transistor you will find +5V (minus some for resistance). This is just one of those counter intuitive parts of digital circuits.

[@alexandersuvorov2002]

What about 0V on the LED end because the current which flows into it isn't sufficient to pass its resistance? Have you checked the input current of the LED when the transistor is on?

[@levih9293]

If anyone is still curious about this, check out my answer above.

[@xonx209]

The output of these gates (as measured on the collector pin) is actually the negative of what the LED is indicating. So the OR gate is actually a NOR

[@Rynstick]

realy unclear i ended up making a intel family gpu

[@Team_qwarxly]

Hmm

[@sakshamchhatkuli271]

Holy shit , I finally understood all the concept behind the logical gates.

[@geneirwin645]

The and gate is really a nand gate because you are referencing the output with vcc not ground.

[@TinyMaths]

This explanation of transistors and how to use them to form logic gates gave me a much more intuitive understanding of truth tables.

[@eliastafese3790]

YOU ARE THE BEST! Vefy nice EXPLANATION

[@tuncaykilic7099]

I was watching the 8 bit computer on breadboard, and wanted to know how the logic gates actually worked. after some video's where they don't really get in to the circuits i found this video. This channel has everything i ever needed hahaha

[@atenakitabi3769]

Oh God wish I had found this video 2 years ago

[@jenniferw8963]

I love this video. I understand digital logic and have made a small cpu in a class using logicworks gates.. but never understood how a gate works at a transistor based level. This is so easy thank you so much for the video.

[@LoneRegister]

Ben Eater - in the inverter circuit where the LED turns off when the button is pushed (around 3:30). I can't help but thinking of all these circuits that are open/flowing current - eating up energy. Typically, when I think of a switch, I think of current flowing or not flowing. yet in this design, current is always flowing?

[@10bokaj]

The led does not have a resistance, but a voltage drop, now the LED does not turn on because a parallel connection always has the same voltage drop, but the transistor does not (as far as I know) have a voltage drop so the voltage drop will be 0, and an LED needs about 2 volts to turn on so therefore it will not turn on

[@johncochran8497]

Yes, in the above circuits, there is always current flowing. And the circuits he's using is very similar to TTL which was noted as being high speed, but power hungry. But there are other methods of creating the desired logic. Take a look at MOSFETs for instance. With those components, you don't have a constant current flow from the base through the emitter, what you instead is charge and discharge the gate as if it were a small capacitor. So you get power consumption whenever a logic element changes state, but otherwise, there's no current flow. And from that, you have what's called CMOS.

[@3DPDK]

You are absolutely correct and John Cochran's reply is 100% the best answer to your comment. Having worked in the design area of an electronics company in the late 80's "idle current flow" was a big concern for a company wanting to reduce the power consumption (and heat degradation) in their product. TTL logic circuits were designed (in the company where I worked) so that if their output was high or conducting over 65% of the time, that output would be inverted, if possible. This actually made the overall circuit bloated with "decoding" logic to re-invert the signal, or PNP instead of NPN transistors were used as drivers, but it did reduce the "idle current flow" ... in some cases. TTL (transistor/transistor logic) ICs are fairly rare in today's digital circuits - discreet transistor logic gates such as these are even more rare and only used to buffer logic IC outputs to high current loads. Even that has mostly been replaced with Field Effect Transistors who's current reducing attributes are explained by Mr. Cochran.

[@Redh0und]

in this case its reffered to as high or low. in this kinda desing you can't have literally nothing as "low", that would equal a shut off computer

[@SvetlinTotev]

well in real computers the output of almost every transistor is the input of another one which doesn't drain current except for when the state is changed. Also There are other types of transistors as well which deal with that inverting problem.