Astable 555 timer - 8-bit computer clock - part 1

[@Mirandorl]

Forget netflix, I just found my latest binge watching source

[@bobdagamer640]

TheDroidBay yep

[@syrus3k]

Totally. I just realised I have the components to make this too... It's gonna be a long night

[@merofuruya_]

I feel you

[@mdasikkhan1610]

@TheDroidBay I like how the comment has 555 likes hahaha Ah man its not 555 anymore

[@johnjordan3552]

This is better than anime, and possibly at least 1.667 something times more entertaining than watching hentai

[@cobra646]

By far the best explanation on the 555 that I have seen. As a total beginner this was great.

[@Decco6306]

that's because he doesn't have a thick middle Eastern accent you can't understand

[@ritvikvaishnav3472]

totally agree.

[@Bu7MaiD075]

Kipper Klank as a middle eastern, I agree. damn indians ruined engineering videos.

[@MrPnew1]

@@Bu7MaiD075 yeah stick to the Poppadoms :)

[@ianphil397]

It's also the best visual explanation I've seen of how a decoupling capacitor works. Excellent stuff.

[@acf2802]

You got to watch out for those ±100% tolerance Chinese capacitors.

[@markusepple6204]

This is bought cheap not as a timing capatitor, but as a DC-filter it is working fine.

[@lavalamp3773]

If we allow for -100% tolerance, I got some 1 GF capacitors to sell you.

[@Synthetica9]

@@lavalamp3773 ah, yes, I've also seen pieces of wire before

[@tayler6000]

This is the funniest hardware related thing I’ve read in my entire life

[@wreckingangel]

This is why Electrical Engineers always look in the datasheet first, even for a simple capacitor ;) Electrolytic capacitors age, the electrolyte dries out over time, this is why it is overdimensioned. 1uf is the guaranteed capacity at the end of it's rated lifetime. Electrolytic capacitors are usually used to filter DC Voltage for power supplies and stuff like that. They are normally run at around 75% of their rated Voltage and at elevated temperatures which accelerates ageing, if it had only 1uf from the start it would die fast. Electrolytics are a bad (and expensive) choice in this case, for a circuit like this a ceramic capacitor would be better but sometimes you got to work with what you have at hand.

[@amyhicox2578]

As a kid who grew up in the early 80s playing with those radio shack “100 in one” breadboard kits, got to my teenage years and said “well that’s cool, but writing code is where it’s at” ... then dove head first into programming and nearly forgot about hardware hacking beyond plugging things into motherboards ... THANK YOU. My 43 year old self still loves to code, but hardware is so unbelievably complicated and impenetrable now. You have rekindled the spirit of playfulness that I first experienced reading those old Forest M Mimms books. I just found your channel, can’t wait to watch the rest. Seriously, thank you.

[@d0nnyr0n]

@@TheeCK1357 lol

[@traeldor]

@ Andrew Hicox I'm with you. Built my first AM radio in the late-middle 70's, and since the middle 80's have been learning multiple coding languages. These videos have rekindled a hunger for the breadboards. Now to get my wife to understand. LOL

[@amorag59]

​@@BillAnt We need less incels in the world, not more!

[@djcsdy2]

Looking back at them, the Forrest M. Mims books are terrible, or at least “Getting Started in Electronics” is. That’s probably why you gave up on hardware. It’s certainly what happened to me. It goes straight from explaining what an electron is to giving example circuits with totally inadequate explanations of how they work. Digital signalling circuits are covered but it doesn’t even explain what a pull-up or pull-down resistor is for, or even tell you what they’re called. There are just these mystery resistors in the example circuits that aren’t even mentioned in the text. I read it cover to cover and had no idea what was going on. I don’t know why people like them so much but I’m pretty sure it’s just the cute illustrations and the novelty of a published book being written on graph paper. As an instructive text, for me it was worse than useless, and set my interest in electronics back ten years.

[@laurencevanhelsuwe3052]

Have a look at the Tinkerforge components.. as a coder you will *love* them. I've created amazing projects with them.. the end results make you look like you're an electronics pro.

[@ch6339]

Man you're incredibly good, I mean your vids are awesome, you're very clear in your explanations !

[@banderfargoyl]

charles beauville I second this emotion. This is just very well done.

[@fernwood]

Yeah I've been trying to understand analog circuits for 3 decades. This video alone might've gotten me over the learning curve.

[@caiopereira1289]

@@fernwood Hey, there are some excelent tutorials on youtube and on the internet that I can show you if you want. What is your interest in them?

[@aidencoder]

I never "got" electrical engineering, but instead became a software engineer. Ben's explanations bridge the gap somehow for me, and make electronics seem more like programming. I like this.

[@PPSRHD]

Well nearly all computer Innovation is due to electrical and electronics engineering and software just comes later. All initial software was and is made by electrical and electronics engineers as it is extremely low level

[@aidencoder]

@@PPSRHD Yeah and that's all down to mathematicians and physicists. Electronics just comes later. Not sure what your point is. I don't think you have one.

[@Lil_electrician]

@@aidencoder im guessing hes trynna say that electrical is harder than software because it goes more in depth....

[@timecubed]

It really does feel like programming. The reason why is mostly because software engineering is based on electronics and hardware stuff. Similarly, programming feels like electrical engineering (at low levels) since both software and hardware are so closely interlinked at low levels (think of programming in C or C++). Edit: I _might_ not be fully accurate here so excuse me if I got something wrong

[@aidencoder]

@@timecubed you're right, software and hardware are equivalent and the distinction is only where you choose your level of abstraction. All software can be implemented in hardware.

[@BirdYoumans]

My friend, I have watched literally hours of 555 "instructional" videos, I know, I need to get a life, but I also know that once I thoroughly understand something, it's much easier to be creative with it. And in fairness to the others who made vids, some better than others, I'm sure the info is somewhat collective so I know a little of how this works, but I just learned more about this chip in 30 minutes than all the others combined. Your clarity is astonishing. Wish I had found yours first since that would have saved me a ton of time. If I have any wishes tho, I'd like to have seen on the schematic exactly where the pins to the pot and 1k resistor went. I'm sure a few minutes at my bread board and I can figure it out tho. But otherwise, I fully understood everything you explained. Thank you! I feel some binge watching coming on lol!

[@ytytiuiu2590]

I don't know if you could see this or not, but my only advice to you if want to create something is take break, and try experience with knowledge you have .

[@rexor8527]

i know right! I myself am going into a field of IT i dont think can get much further than this, the closest I've ever gotten to this was a build it yourself toy wire maze thing that beeps if you touch the hook to the wire, so I know next to nothing about this stuff really, and yet something about the way he explains things is just so genuine and so complete that it just keeps drawing me back. A real shift from the "this works like this, that works like that, plug this from one into that from another and it will do this because that's how it works" feeling you get from many instructional videos, or even schools.

[@carlospitcher4335]

I have easily seen 20 555 circuit explanations. And I can assure hands down, yours is the best... Thank you!!!!

[@arvinmistry9744]

Great you are the best teacher with detail explanations

[@CharlesPanigeo]

13:55 the 0.693 constant is the first three decimals of ln(2). The logarithm comes from inverting the exponential charge/discharge function to solve for the time.

[@NonEss3ntial]

Can you explain this a little more?

[@NonEss3ntial]

How does t=R*C*LN(1-(Vpresent/Vmax) become t=R*C*LN(2)?

[@g73hc3gsv3i]

​@@NonEss3ntial The output voltage of an RC circuit at time t is 𝑉 = 𝑉max*𝑒^-(t/RC) ∴ t = RC*ln(V/Vmax) For an A-stable multivibrator, charging and discharging happen between 2/3Vcc and 1/3Vcc, respectively. As initially it starts from zero charge, ∴ ON time, 𝑡 = (time taken to reach 2/3Vcc - Time taken to reach 1/3Vcc) t = RC [ln(2/3) − ln( 1/3)] = 0.693RC

[@NonEss3ntial]

Thank you so much! I am an EE student and this is still in my notebook of problems to figure out. Thank you thank you thank you. @@g73hc3gsv3i

[@cheesecake667]

Im blown away by your knowledge and explanation skills. WE students need YOU to be a Professor! Then again, you might as well keep producing your awesome videos and reach an even greater number of listeners. I subscribed. Thank you!

[@Fittiboy]

the .693 coefficient is approximately ln(2), as the capacitor only charges and discharges half way.

[@peabnuts123]

Thank you

[@microm2078]

It only charges from 2/3Vin to 1/3Vin. The calculation for that would be: 2/3*Vin*exp[-t/(C*R)]=1/3Vin t=ln(2)*C*R. So you where right about the coefficient, but it doesn't charge or discharges half way. Im sure thats what you meant, but just for clarification.

[@yiliangliang5694]

lol I've seen this constant so many times (in Chemistry; physics; etc.) that when I saw .693 in the video I immediately know it's ln(2) lol

[@ZzSlumberzZ]

I knew it seemed familiar!

[@adityathakur7604]

@@yiliangliang5694 especially in electrochemistry and ionic equilibrium lol and chemical kinetics

[@unchayndspersonalaccount7690]

0:00 Introduction and Base Circuit Overview 1:42 Base Circuit In-Depth Explanation 17:58 Fixing Transition Noise 19:22 Fixing Overshoot 23:32 Attaching the Reset Pin to 5V 24:35 Adding Speed Adjustment

[@ericrandall3539]

The way you drew the diagram is, I believe, the reason so many people are finding this so helpful. Showing the 2 resistors and cap all in series on the left is by far the best way to visualize this. I wish more tutorials would show it this way. 10 people will draw this 10 different ways, but for many beginners it won’t click until they see it drawn like this.

[@starkiller1223]

"Showing the 2 resistors and cap all in series on the left is by far the best way to visualize this" I agree 100%

[@AlanCanon2222]

I just made my 6502 Ben Eater computer say "Hello World." Now coming back here all the way to the beginning to give my now-battered and war torn Ben Eater clock module a check up, and revisit this great old video.

[@jeffmerlin2580]

The best 555 explanation I've seen. Having watched the SR-latch video also helped a lot. Thanks!

[@FranciscoLopez-ym6gd]

Hello from Colombia . I normally don't comment , but this is the best explanation that I have seen , and ...... I dont speak English very well :) .

[@monchosalce]

Eso pacho

[@deltakid0]

Pacho u_u hello from Colombia too, the video has auto generated closed captions so while you are learning about 555 you also learn english :)

[@pumpkin6429]

Hello from America. Fuck yeeahh! Bet you dorks wish you where here. 😂

[@noble6430]

@Pumpkin Idk. There's a reason I decided to stay on Reach you know.

[@heh2393]

@@pumpkin6429 What is wrong with you? American exceptionalism maybe?

[@Mark-id7uy]

are you pointing with a piece of uncooked spaghetti?

[@RoboGenesHimanshuVerma]

😂Its just single core wire with the sheils on though

[@ryanjl9]

Variable resistors, for when you need to overclock an 8 bit computer...

[@jegarretson]

Capacitors have a tolerance rating, just like resistors. Electrolytic capacitors typically have a tolerance of -20% to +80%, but it's not unheard of for low quality electrolytic caps to have tolerances of -50% to over +100% which explains your "1µF" cap reading as ~2µF. Also, if you were to connect another 1K resistor from the junction of the two timing resistors directly to pin 7, your duty cycle would remain much closer to 50% and would negate the need for the other resistor you added when using the variable resistor. As to the connection from pin 4 to your positive rail, it's generally safer to use a small (

[@robmckennie4203]

if it's a tolerance thing, why are they all off by the same amount in the same direction?

[@John_2143]

my best guess would be that they're all from the same batch, so they all act similarly

[@michaellee9743]

Also I have seen 555 circuits which don't trigger because the charging current is less than the electrolytic capacitor leakage! Electrolytics vary wildly with temperature too, so best to keep the capacitor

[@telefon72]

Because then they can sell 1uF and 2uF capacitors, but only make one.

[@BrightBlueJim]

The key to this is that electrolytic capacitors are use almost exclusively for filtering and DC blocking. In these applications, designers want at least a certain capacitance value, which explains the -20/+80 tolerance. Also, because electrolytic capacitors tend to drift to smaller values as they age, the manufacturers try to design them to start their lives at the high end of their tolerance range. This makes electrolytics generally unsuitable for timing circuits. The same is true for ceramic capacitors using certain ceramic formulations (sorry, I don't know which ones of the top of my head), but they are generally much closer to their rated values than electrolytics. If you want a precise timing circuit, the best bet is to use either polystyrene or polyester capacitors, but in any case, look at the datasheets. Capacitors really AREN'T purely generic components. Of course, it's much harder to find 1 µF capacitors in polystyrene or polyester, so the resistor values also have to change. Not a big deal unless you want a really low frequency, as in this particular circuit.

[@splitzerjoke]

Wow. Back when I was a kid, I used to be a drummer. Through practice, I accustomed myself to the duration of a second to keep beats constant. When you computed the period for the first time, I immediately knew it was off; the true period must have been something around 1/4 - 1/5 of a second. Almost got it! :) I knew drumming would come in handy sometime haha

[@BillAnt]

Well at least you're marching to the beat of your own drum and not to a 555. ;)

[@geraldbull9272]

Really like this chap, he talks down to earth, explains it well, not hyped and above all no music in the background, sanity at last.

[@jimedgar6789]

WOW! I have been using these things forever using the formula thinking there were elves inside doing all this shit. The impedance fix was something I have done but not knowing why! No wonder my stuff always blows up! SUBBED and sending you a Red Lexus Roadster!

[@TheSunriseAnimation]

Or gnomes and they come out and complain when the sand for their hourglass runs out.

[@aSeaofTroubles]

In 20 minutes I've learned more about circuits than my entire intro class to circuits!

[@skilz8098]

That's because institutions are profitable business and they want your hard earned money to keep you in debt (poor) while they stay rich. They only teach you enough about the topics but force you to learn on your own. Then again it may also come down to the individual institution and professor. They won't teach you everything you need to know in a concise clear manner in the shortest time possible. The want to stretch it out over as much time as possible and even throw in a few bits of confusion just so that you would have to take another course for another semester so they can make a few more thousands of dollars off of you. Now as for Ben on the other hand; he has the knowledge and capability of building such systems and he actually enjoys sharing what he knows through his public KZbin videos. He understands that your time is worth something, so he designs his videos with accuracy and just enough details and information needed to actually understand what is happening within the circuits where all of the mathematics, the circuit diagram, the logic diagram, the truth tables are all taken into consideration and to top it off, he uses breadboards to demonstrate the theory by putting it to practical tests while explaining where all the connections are going to and from for the direction and amount of current from one part to the next. His videos are by far the best illustrations for generally anyone to understand the internal workings of computer hardware, either it be the CPU, RAM or some other device that uses circuitry and memory. This is far more profitable than spending 20 - 80k for a 4 year degree at a University where you still walk away 1/2 confused...

[@crateer]

@@skilz8098 totally depends on the country though, and totally not in europe lol

[@thomasesr]

with the 5k, 5k, 5k resistors inside. They would either call the chip the 555 or the KKK... I Guess they preferred de 555 for some reason...

[@DavidTangye]

Thomas Richter it is not called a 555 because of the resistors. That is just a coincidence.

[@aidanfransen3571]

its not a coincidence...

[@petr_e]

That's a common mistake. There's no sense behind 555's name. Here you're able to read an interview with Hans Camenzind (an author of the scheme) about the name www.quora.com/Why-is-IC-555-called-555-Why-not-111-or-any-name

[@kurtisodonnell321]

Yep its coincidence, that is (from memory) the 555th IC they made

[@petr_e]

Oh, man... Just a cite from Hans Camenzind (an author of the scheme): "Signetics had “500” numbers, and the earlier product I worked on was the 565, 566 and 567. It was just arbitrarily chosen. It was Art Fury (Marketing Manager) who thought the circuit was gonna sell big who picked the name “555”"

[@davidhanley6437]

I don't think I have ever heard an explanation of 555 operation and circuit design as clear and understandable! Looking forward to watching your other vids. Thanks!

[@power-max]

The tolerance of electrolytic capacitors can be quite bad! Like, +-80% bad! Those could very well be within tolerance!!! :O

[@musicbyvec1955]

At first I thought he was pointing with a dry spaghetti

[@oussamaelhriki8160]

😂😂😂😂😂

[@ilustrado7291]

Did you see vomit on his sweater already?

[@maleknecibi]

Ilustrado - Well on the surface he looks calm and ready, but maybe he's actually nervous

[@joekanaan2548]

@@maleknecibi but he keeps forgetting what he wrote down

[@valuedhumanoid6574]

Your grasp on electronics is off the chart. There's no better feeling than leaving a video understanding a concept you had no clue about. So good. That's worth a like and a sub

[@kirillazarov6865]

We have this, and some people will still prefer to watch the news. It's a crazy world we live in.

[@linuxman0]

By watching your explanation of the 3 resistors, I think I figured out why we use 5V and 3.3V.

[@jimknight5675]

I’ve been involved in electronics for 43 years and have never seen such a tutorial so clearly explain the function of a 555 timer, you are an excellent teacher and I wish you had been a lecturer at college when I was there.

[@philpesce]

Years ago a fellow engineering friend of mine and I decided to build a circuit with a 555 timer. He’s a mechanical engineer and I’m an aerospace engineer turned software engineer. We had no idea what we were doing but managed to get the timer working. Fast forward to today and I just sent him this video and we are both watching it simultaneously from across the country. This is awesome and I bought the kit! Thank you, Ben!

[@varshneydevansh]

Just a question why you switched the AE to SE as I also seen a lot of AE doing this. Tho. asking as my little brother is about to enter in STEM college and somewhere AE is we are considering.

[@DavidRTribble]

Note that the coefficient 0.693 is ln(2), or the natural log (base e) of 2.

[@adnamamedia]

a really fun project would be building a 555 without integrated circuits

[@jeromethiel4323]

The 555 timer was celebrated as a seminal development in integrated circuit design. Just like the 741 op amp, they are ubiquitous because the basic design was just that darn good. Also in that class in the 16550 UART. Some designs are just so good they transcend time.

[@sebastiantroue6320]

1 mFd means 1 micro Farad double☝️

[@laughlinmccooey8575]

Can't tell if this is legit or a joke...

[@anythingandeverything264]

@@laughlinmccooey8575 its a joke theyre probably cheap +/-100% caps

[@notserpmale03]

Just Cause THANK YOU

[@nipz8053]

That's what threw me off looking at that component.

[@TheQWERTY173]

I am finishing up a digital logic class and wish I would have had your videos. I will definitely be using them to study for the final!

[@sjgsteve21]

That’s wild man. I’m a mech eng and work in an R&D lab with hydraulics all the time. When he plugged that capacitor across the power lines a light bulb went off and I realized it’s no different than putting an accumulator on the pump supply line to reduce noise. You are a great teacher! Loving these vids

[@shawnmuench]

Holy shit that's a cool connection. I'm not an engineer of any kind, but that makes definite sense intuitively.

[@eritain]

The analogy between electronics is extremely close. Voltage is pressure. Current is, well, current. For any basic electronic circuit you can literally build a hydraulic simulation of it. I think I've seen a learning kit that actually did that ("for children" ... um, yes, I would buy it for "my child").

[@topilinkala1594]

@@eritain When I try to explain how resistance and capacitance work in AC circuit I always talk about seasons. The light pressure from the sun is highest on the summer solitice (northern hemisphere) but that is not the hotest time of the year. Athmosphere acts both as a resitor and an accumulator for the heat. So the max heat is phase shifted to about August. Same thing happens during winter when lowest light pressure is winter solitice, but the coldest time is in January-February.

[@superdau]

There's an easier way to get a 50% duty cycle oscillator with an 555, although you should use the modern CMOS version for that. I find it weird that I hardly ever see that circuit used. Just ignore the discharge pin, remove the 1k resistor and connect the output itself to where pin 7 was connected. Easy 50/50 duty cycle with a single resistor and capacitor.

[@epiendless1128]

A useful reminder. I had forgotten that you need the 7555 for that.

[@zealphanerd1]

I have never had a 555 timer explained to me so well. I understand this 100% now. Thank You for that!

[@vincentmoon9919]

Is it just me that thinks that he should just try to cough

[@batchrocketproject4720]

I like returning to this video when I need a reminder that there can be order in a complex world. A few years ago I carried the (huge) 555 data sheet around with me for about a month, studying it in every spare moment. This video does a better job than hours of reading. Thank you Mr Eater.

[@robinharris4706]

I've watched a few tutorials on the 555 and I agree with another comment - this is by far the best. Extremely clear explanation - you have a rare ability to speak without hesitation or repetition. The video quality is crisp and everything is easy to see - even small details. Excellent. Please make more tutorials!

[@MrTrumanPurnell]

BEN THESE VIDEOS ARE INCREDIBLE!!! SO THOROUGH ! NEVER STOP !

[@8bits59]

Those capacitors, judging by the "MFD" unit label, are older than dirt and have become electrically leaky, hence the high reading. Allow me to explain. Imagine an ideal capacitor. Two plates, with a gap. No DC current will flow through them once the field is built up. Non-ideal capacitors have a characteristic called leakage current, which is the amount of expected DC current flow between the plates due to things like electrolyte conductivity, ionization and metal migration over time under the force of the electric field, etc. As some types of capacitors like electrolytics and the old paper and wax capacitors age, they leak more and more DC current across that they shouldn't, and slowly start to build a parasitic resistance that decreases as the capacitor ages. Since the parasitic resistance is in effect in parallel with the capacitor (because the leakage current occurs between the plates) it causes the capacitor to take longer to charge. Most multimeters read capacitance by passing a small, known current between the leads and then sampling the voltage over a specified time (basing the reading on the fact that larger capacitors take longer to reach any given voltage at a constant current), meaning that any leakage between the plates of the capacitor will cause the reading to look high because of the parasitic current draw keeping the voltage down. Slap one of those capacitors between the leads of an old capacitor leakage tester and see how badly they leak. Some of the older caps I've seen can leak current at a charge as low as 2-3 volts. No doubt those are the same.

[@epiendless1128]

Indeed. It would be interesting to find out if the capacitor was equally inaccurate at higher charge currents, and whether the electrolyte barrier would reform over time if the capacitor was kept in constant use. As I'm sure you know, the electrolyte itself is conductive, but passing current though it forms a thin insulating layer of oxide on one of the capacitor plates, and this thin layer is what makes it a capacitor (and indeed a _polarised_ capacitor).

[@pwkoert6594]

That tels me that we measure the load time of the capacitor, I usually measure UN-load time, with the opposite result of course (many of my parts are 20jrs+) Because my first 5 555 experiments went wrong, I did not think much of if, now I am gonna try again... thanks to Ben and all use full comments.

[@edwardvermillion8807]

and here i am thinking 'mfd' just stood for 'mf' doubled...

[@chrisbroome]

By far the best explanation of the 555 timer I've seen. Specifically, the layout of the diagram makes it easy to see how the charge builds up to set the S, then the R, and then finally toggle between them.

[@kilak9193]

Is it sad, that you can get a "real"/"modern" computer for less (money)? Still a good way of learning, don't get me wrong.

[@lewishbutler]

The best explanation of a 555 ever. Now I want to build a breadboard computer using these tutorials. Thanks. Still useful in 2017

[@Aemilindore]

What a wonderful video. The way you demonstrate power supply impendance. We shoid teach this at university this way

[@junglepolle]

Asking just by curiosity. At 12:00 you talk about the rate between on and off time (duty-cycle). Wouldn't you get 50% duty-cycle if you placed another 1k resistor before the discharge-transistor? Nice video btw!

[@rustyz4014]

Change the LED to a relay and a motor, and you have the circuit for the delayed wipers on your car. Nice job.

[@skilz8098]

Or just plug it into to the turn signal regulator, but you might want to slow the pulse down just a little bit...

[@Engineer9736]

I don’t think the 555’s output is able to deliver enough current to trigger a turn signal relay. Even if it’s able to do so for a while, it will become quite hot.You’ll need to add a big transistor in between or a FET.

[@juliet0001]

@@Engineer9736 no, you would use the turn signal clicker instead of the 555

[@viveksinghal1108]

Can you use a voltage follower to get the extra current?

[@Multibe150]

@@Engineer9736 What about an optocoupler? Or even a relay-optocoupler combo

[@banban8481]

Hello Ben Eater, I want to thank you for your videos and KZbin channel, I first saw your video when I was in high school and just started to learn electronics, and now almost 7-8 years have passed. I became an electrical engineer and chose electronics as my specialization. One of the many reasons is because of you, thank you very much for your tutorials and please keep making them. Maybe for you, it is just a video but for us, it is changing the world.

[@michaelhamor6113]

Silly question. I've been working my way through Make:Electronics. Chapter 11 has you build an circuit out of resistors, capacitors and transistors gives and alternating on off signal with a nice square form. Frequency can get very high and seems stable. Could you use that as the computer clock instead? What draw backs would there be compared to this setup or even a quartz clock setup?

[@billtasker4372]

The 555 is difficult to understand but Ben Eater is a great teacher. Thanks.

[@Penfold8]

I had always heard there was capacitors that show "+" on the capacitor rather that the "-" sign. This is the first time I have actually seen the "+" designation.

[@floriangassmann272]

I was so confused about why his capacitor is plugged in the wrong way round because i only payed attention when you could see the top of it...😅

[@timothycarpenter9947]

The 555 is simple - but the thing I hate about the 555 is the drift that makes precision and high speed clocking difficult or impossible.

[@patprop74]

great explanation and your drawing does make it easier to understand, I am somewhat new to electronics, I know the 555 is rather cheap in price, so what the difference between using the 555 as a clock or to blink a led, compared to using a npn transistor and a cap? which is a lot cheaper.

[@JanicekTrnecka]

Dick Fageroni In fact you can, but its pretty nasty solution. Avalanche effect in trsnsistor makes it conductive, dischsrges a cap and the cycle repeats. But the edges of such clock are nasty snd it has a pretty nasty voltage spikes.

[@arthurfricchione8119]

Very well explained video. I’m new to electronics ( retired aircraft mechanic in the real world) but am now diving into this field and trying to teach myself from the bottom floor and working my way up and your videos are excellent. Thanks for sharing Artie 👍👍👍

[@bluekeybo]

love your videos. I'm an electrical engineer and just found out about your computer project. awesome!

[@michaelmele3954]

What happens if you just use an alternating current for your clock signal?

[@Madjam-cd2fk]

Michael Mele the only thing online I could find that used AC current for a clock is this clock hackaday.com/2010/04/07/logic-clock-without-an-on-board-oscillator/ AC current is fairly consistent but can vary by a bit from day to day so it’s not ideal for something that needs a consistent signal It’s also inflexible only going at a specific hz

[@michaelmele3954]

@@Madjam-cd2fk Thanks a lot! I guess it's not a well trodden path, which is something I didn't know before. I'm guessing that your AC input signal could be as flexible as you want to make it. Are we stuck with the 60 Hz coming out of the power grid, or is it feasible to custom build an adjustable and regulated AC power supply at any frequency you like?

[@nistax2880]

well these chips are all analog (in the computer) so thay would have some problems / unexpected behaviour with a analog clock

[@rj-nj3uk]

During an intro lecture to 555 timer, our professor asked "Do you know the use of 555 timer?" to the class. And everyone in class having no idea was like "maybe to make time bomb?". XD

[@Sierpina_WMG]

A repeating timer? That's not even a good answer.

[@Douglas.Kennedy]

you only need one count to trigger a device- a big capacitor and a comparator would do. don't waste an entire 555 timer! unless you need a count down timer, then you can use the 555 to generate a clock to run a counter. put the trigger on the most significant bit 😜💣

[@maxgh1234]

How do you come up with the shematic at 2:52 to walk yourself through the process? Or is it by knowing how this works beforehand?

[@Blinkation]

Finally! I get it now, thank you very much.

[@robertharold1190]

I received your clock kit as a birthday gift this year. This is the first time I"ve ever look at an IC and really understood it. The way you drew out the diagram, arranged from left to right, was a great breakthrough for me. Thanks! I'm looking forward to building the kit and learning.

[@sikor02]

This is gold

[@edouardvincent7983]

it s really good ! thanks for your explication best youtube's video ever !

[@GORF_EMPIRE]

The 555 does indeed get it's number name from the fact that there are 3 5k resistors on the comparator inputs..... just sayin'

[@VoidHalo]

Very helpful video. I love this series. The reason your caps are 2uf though is because the tolerance of electrolytics tends to be very low. I can't remember off of the top of my head, but I remember when I first started using 555s I came across the same problem. If you use tantalum capacitors you can get a much more accurate value.

[@deltakid0]

awesome!!!! thank you for this!!!

[@RussellCambell]

Also you have some seriously sick breadboarding (neat and clean) skills

[@micahcowan]

For novices like me: note that while you'll want the electrolytic (cylindrical) capacitor's white stripe on the (-) side, in the video it's on the (+) side. Your capacitor polarity should NOT look like his, for some reason he's got one where the + is striped instead of the - (which you can confirm when he takes a closer look to figure out why it's 2uF). Also, in ceramic capacitors in the video, the 0.1uF one looks wider than the 0.01uF one (which makes intuitive sense to me), but in the kit it's the reverse (which had me second-guessing myself). Don't let the size concern you: 104 is 0.1uF, 103 is 0.01uF, end of story. If you're fairly inexperienced with electronics (like me), go read or watch some stuff that ensures you understand how to read the components (especially the resistors, the ceramic capacitor, and the polarity of an electrolytic capacitor). I knew to refresh myself on these things, and got everything right on my first attempt; but I was heavily doubting myself until I switched on, because the components in the kit and the components in the video were very different! Also if you're reading this before you've gotten to the later videos, be advised that the part 3 video is WRONG for this kit (the switch will still work, but it WON'T be de-bounced - the video is using a break-then-make switch, but the kit has a make-then-break, and that very much matters). Look for a comment by Sergey that sets you straight on the simple but necessary modifications (reversing the logic). You can follow the video, confirm that it doesn't work when you very slowly slide the switch, and then make Sergey's modifications if you like - it won't hurt anything.

[@citruscampbell]

I'm sorry I love your videos but you need a muffler or something 9:18 I have sensory issues and the constant gulping is so annoying

[@47Mortuus]

Ben Eater: "We can pull out a calculator here..." Phone: "Am I a joke to you?"

[@christianniemeijer97]

Dude, I've been watching your videos for some months now and finally I made my own clock using the kit. Next up I will be building the whole computer! Thanks for sharing, it is an invaluable piece of knowledge that you are sharing with us computer science fanatics

[@Captaincodeine]

.693 is log(0.5) and is the half decay constant. I'll never forget it because it was in Feynmans book

[@DantevanGemert]

Actually, it is -ln(0.5), which is the same as ln(2)

[@Captaincodeine]

@@DantevanGemert you're right.

[@dru6809]

Which book?

[@Seltyk]

My 8th grade required electronics class had us use the 555 timers without any explanation of how they work or what they do, and now, however many years later, that hole in my mind has been filled. Excellent explanation!

[@zeusnitch]

12:03 "Doodie cycle" All I can think of is Catbug laughing.

[@bertieblob3387]

The best description I have come across of how the astable 555 timer configuration works. An exemplary example of how simple, clear thinking can de-mystify something that, initially, can appear complex and difficult to understand.

[@daveb5041]

Can you overclock it by putting on a liquid cooled heatsink on the 555 for speeds up to 20Hz then play crysis 3 on it at 80fps?

[@mentalyunstable2872]

Dave B 20 Hz is incredibly slow......so no

[@OtherTheDave]

Yes, that is exactly how that works

[@Luis-cc6rp]

mentalyUnstable r/woooosh

[@nerijusvilcinskas7851]

I graduated in electronics engineering last year. With no luck in finding job. These videos are so interesting, latches and flip-flops are so easy! I mean in uni it was so hard to get these concepts and you are much better at explaining things.

[@shvideo1]

What an awesome comprehensive project. Thank you for sharing your great knowledge, including the oscilloscope demo and corrections.

[@azakusilov]

Dude, your videos are treasure. We need to preserve them, and everyone interested in electronics should see them. There are lots of people who have this knowledge, lots of books and stuff. But many are written in a way that it's very hard to understand for someone new, who just started learning. Your videos are done in a manner in which it's very easy to understand, from simple to more complex, step by step, in a very clear way. This is how education should be done. Spending months in some school learning nothing, or watching your 30 minutes video to learn actual stuff!

[@youpie]

I have a question, is the 1k resistor necessary or can you just leave that away?

[@tomkennaugh]

If you left it out the discharge transistor would effectively short out the power supply when on

[@vinayakonimani7628]

4:20 its not a coincidence, 555 timer is named as such just because of its three 5k ohm resistors

[@NorthbyWest]

As a novice, I am playing with the 555 for some toy projects for the kids, but I never knew about the 'magic inside'. Outstanding explanation. Subscribed in order to follow more.

[@mattfirestone1]

I can't get my LED to blink. It just stays on constantly. I have tried different timers, on different boards and nothing. The only difference is that the kit I have shipped with 1m capacitors instead of 100k. Anyone have any ideas?

[@aliarshad3012]

I am experiencing the same issue. I tried 2 different 555 but same result.

[@rodmongodwood]

ok i have a question i always wanted to know.... why on earth do you guys (i assume Americans? but dont know) draw GND connections with the Earth symbol? i know it with just one big line it confuses the hell out of me every time i see such a schematic. the funny zigzag resistors i kinda got used to because they don't look like something else

[@pumpkin6429]

Why do you Europeans whine about Americans doing things differently than you? Yes, they're an entire ocean away from you, of course shit is gonna be different.

[@nistax2880]

it's because its a ground common ground , he actually used just one line on a capacitor because that is ground just for that specific capacitor (I think ) btw from eu so idk

[@Enigma758]

Can someone please explain why this slight modification to the circuit doesn't work? kzbin.info/www/bejne/iKuUcqRperF-sLs

[@pj4717]

The coefficient 0.693 is ln2. It's just the "half life" of the decay. You find it from this equation N0/2=N0exp(-t/t_half). Since it goes from 2/3 to 1/3 that makes perfect sense.

[@fritzbuild3r]

My son (11) is building this project. I am getting the components for him and he is building it from watching Ben’s videos. Should be finishing the 555 clock this weekend. Making just some brief videos showing our progress.

[@milin_234]

Really hardworking and with excellent explaining skills ...best luck for your future...

[@georgevendras5450]

Hi there. Absolutely exciting lectures!!!! As for blinking rate, I think that if we want T_HIGH = T_LOW it would be better to use a variable capacitor and not variable resistor. This is because for the for the resistor values R1 = 1k and R2 = 100k we handle it mathematically as that: T_HIGH = T_LOW => 0.693*R2*C1 = 0.693*(R1 + R2)*C1 => we need R1 ~ R1 + R2 => we should select values so that R1

[@VeranoggaSystems]

When I'm attempting to measure the voltage across the capacitor with my "oscilloscope", my led no longer oscillates. It's just on, any thoughts on why this might be?

[@r.murphy2311]

I don't have the answer, but I ran into the same thing (when you probe the capacitor with the scope the light just goes "on"). Interestingly, if you probe the capacitor with a multimeter it doesn't disturb the circuit. The other thing is that it seems to be frequency-dependent. If you bought the kit from Ben it comes with 1Meg resistors, not 100K, so the blink rate turns out to be like .6Hz or something if you do the math. When you drop in the potentiometer and increase the frequency to something > 1Hz now you can probe the capacitor just like he demonstrates here and the scope doesn't (apparently) disturb the circuit. I would be curious to know why the scope disturbs things but a multimeter doesn't, also why is this disturbance frequency-dependent? It almost seems like the capacitor never discharges in that low freq configuration with the scope probing it.

[@rohros1988]

No other channel or institution had done this type of clear n precise explanation that clears concept within few minutes...great work n great channel....

[@zecko9534]

Can i put a resistor straight from the output to the LED

[@iancraftsandmines6266]

4:13 When you said that I laughed, looked at my clock, and it was 5:55 P.M.

[@gettingpast4391]

This is the best explanation of how a 555 timer works (internally) that I have ever seen. I was wading thru breadboard computer builds, and this video alone was enough to make me subscribe. So far every single video in this playlist has been JUST AS GOOD... everything explained perfectly. Subscribed! THANK YOU!

[@silverion2608]

I've struggled to understand how the 555's astable mode works, but this video gave me a perfectly clear explanation. Thank you so much for the walkthrough.

[@gerrymcerlean8432]

An absolutely brilliant explanation of the 555. Thank you. As for the capacitance issue; electrolytics are notorious for their wide tolerances. These can be as wide as -20%/+80% when brand new. They then deteriorate further as they age. They really should not be used in any 'timing critical' application. Your caps are particularly bad though. Bet they came from China via eBay.

[@arthurfricchione8119]

Ben, I’m a new subscriber to your channel. I’m a retired aircraft mechanic and not familiar with electronics. Anyway I’m taking an automotive electronics course to learn how car computers function and 555 timers are very prevalent wether in the test equipment or the computer itself. Thank you for posting these videos so I can get a better understanding of the roll that they play. Thank you and glad I found your channel 👍

[@AlexanderLeset]

Also an ex-aircraft mechanic. I was supposed to be a computer programmer but got switched to crew chief in basic. I wish I could have been a specs guy at least because my favorite part of the job was always going through the fault isolation trees and the more logic focused parts of the job. These videos really scratch that itch for me

[@qweqweqweas7273]

Oh ps get on patreon I'll pay you for more of this. I'm a poor Uni student 🎓 but $10 a vid I'll fork over. (No 5 minute jobs plz ;) )