How 555 timers Work - The Learning Circuit

[@alexvonbosse5090]

this is one of the best explanations of the inner workings of the 555 timer that I have seen in a long time!

[@Dingomush]

I’ve watched four different explanations on the NE555 internal workings and so far this one has made the most sense. A bit fast in places but it’s a video, I can go back and watch it again and try to pick up what I’ve missed. Thank you so much for your time and expertise on the subject matter and for “dumbing it down” in plain words and diagrams so that more people can enjoy electronics.

[@migalito1955]

Very nice tutorial, especially given it can be configured 3 major ways. I am a math guy that hobbies in electronics and studied the 555 a few months back. It was nice that your video mentioned that the integrated flip flop actually used only one of the outputs which is a detail that often is overlooked in other explanations. I ended up building an astable Multivibrator so that I could put out a weak signal in the AM broadcast band spectrum in order to test reception capacity on regenerative radio receivers that I assemble from parts at hand. It worked, barely. By barely I mean that high a frequency was kind of pushing my luck. Without filters it was also broadcasting everywhere much like a skipping stone across a pond.

[@akashsunil7464]

How did u manage to do that how could you send out a wave using the 555 timer never mind I am a late bloomer my brain would take too much time to process but I would very much love an explanation

[@migalito1955]

@@akashsunil7464 Its been a year or two, but as I remember I set the IC555 to the highest frequency that I could get it to oscillate at using the configuration shown on the data sheet. This was a matter of selecting as I remember resistors at specific pinouts. The frequency that I was able to get was around 500KHz. I then added an audio transformer to the endeavor so as to inject audio such as a tone, into the signal it was generating thru being allowed to oscillate. It was a lousy transmitter but it did put out enough mili-watts to be heard by a radio in the next room. It also had a square wave & produced harmonics all over the place. Its kind of funny in that back then I spent a day or two understanding the entire innards of the chip & what could be done with it. I barely remember any of the details anymore. None the less its better suited for turning your car's dome light of than using as a low power transmitter

[@antonnym214]

First time I've seen an understandable description of this chip. Thank you. By the way, I have a friend who says he's bistable, but practicing as monostable because it's just easier to live that way. All good wishes!

[@MAYERMAKES]

i used them a lot but never looked closely opn how they work, very informative, thx Karen!

[@solapowsj25]

This is one of the best presentations for working of the 555. We've used the 556 as astable and monostable together to produce a PWM signal for a Boost Converter, 12v t0 48v DC at St. Joseph's Research, BLR, IN.

[@mehran_sk]

I have seen so many videos about 555 in my native language but somehow they were confusing until i found this video simple and understandable even with a foreign language description

[@gamergamer6241]

Great channel! Your explanations are so clear

[@LeoStarrenburg]

A good 50 years ago I started in electronics making my first medium wave receiver with an ECC82 valve. A year or two later, in 1972 the 555 was introduced and I've been dabbling with it ever since. Thank you Hans Camenzind ! Nice video BTW 👍.

[@spudnickuk]

This has got to be the best video i have seen that explains how to use a 555 chip with proper illustrations of how it works

[@Valleedbrume]

Arguably the most used timer ever.I started using this in the 70’s.(okay I just dated my self:-)Great explanation.!

[@gregbrockway4452]

Don’t feel bad, me too. One of my favorite ic’s.

[@NkanyisoSatywa]

The explanation that left me with no questions. THANK YOU

[@jimhenderson2308]

Great video. I’d also add that the rs latch is basically an electrical version of a mechanical toggle switch. But unlike the mechanical toggle switch the rs latch has 2 dedicated physical quantity inputs (either high or low) to change the state of the output. The mechanical toggle switch has a single algebraic input consisting of the application of a + force or a - force to change states. This 555 timer is an example of an application of the rs latch thru the use of the 2 comparators assigned to each of the 2 physical quantity rs latch dedicated inputs. Such a configuration can be used for automatic temperature control as set with a thermostat . And so that’s potentially an additional practical implication (besides an oscillator) of an rs latch configured with a couple of comparators to change states to turn furnace on or off to reject heat loss effects thru the walls of a heated building. Unlike the oscillator both the period and duty cycle of the 555 output behavior in the furnace example will change depending on outside temperature.

[@claytonbenignus4688]

Great Graphics!!! Contrast and highlighting is properly used without unnecessary distractions. The “ how it works” part is fascillitated by Karen, who shows both Teaching Experience and Knowledge of the subject. As a Presenter, she is comparable to Liliana de Castro, who does Group Theory for Socratica. All pins were covered without the dismissive “ this pin is seldom used” . I hope to see Karen in more videos.

[@zetaconvex1987]

A little bit fast in places, but a very useful video nevertheless. It certainly helps to demystify what's going on in the chip.

[@RC_Cola2020]

I had to watch this 5 times to wrap my head around it. Not your fault. Thank you.

[@ranjitfernando5241]

Fine explanation. Had watched many tutorials but this was the best. Thank you so much. A small point. In your next videos please try to make a little bit slow in words. As some of my friends felt so. Then persons who are not very conversant in English will enjoy it more

[@Rodderick45]

Fantastic job done! Well defined and explained. She is great!

[@IFixOldStuff]

Great work here showing how the basic building blocks become more complex circuits

[@koszynek]

Super prezentacja, doskonale wytłumaczone. Dziękuję.

[@REXXSEVEN]

Do you see anyone else here speaking that?

[@anthonyshobbycorner]

What an amazing video explaining the workings of the 555 ... So well explained .. Gave me a far better understanding of it ,and how to use it , in all 3 forms ... Excellent video .. I also checked out the 2nd video you did as well .. Regards, - Anthony

[@lucyalicenox5871]

Thank you so much for helping me figure this out!!!! It took me a long time to conceptualize how ICs work

[@gaminghighpriest5293]

omg finally a fully detailed tutorial for people who hav 0 knowledge

[@tuananhnguyen8998]

Nice explaination. I have 1 question. In the block diagram, transistor at pin 4 is appeared to be PNP type. To turn it "ON" isn't that mean BASE voltage need to be negative compare to EMITTER? In the video you said when ever pin 4 is grounded, the transistor is "OFF" which is contradict with what I understand about PNP transistor type.

[@zeeebrenn]

Yes, you are right, the pnp explanation is wrong, when the reset pin is pulled high to VCC the transistor is off. But her schematic is correct.

[@GrowlyBear917]

@@zeeebrenn I was just going to say the same thing but you beat me to it by about 17 hours. Note to self: Wake up in the MORNING, not the EVENING. And, Happy new year.

[@dmitripogosian5084]

@@zeeebrenn Yes, and I guess that is why in applications when the reset pin is not used, it is permanently connected to VCC.

[@JojoDajay]

Your observation is accurate. The IC indeed becomes active when pin 4 is high, and applying a low signal at pin 4 resets it. To rectify this, we can interchange the positions of the switch and resistor. Specifically, we can connect the switch between VCC and the base of the PNP transistor, while the resistor should be connected between ground and the transistor's base.

[@WACkZerden]

Thank You, this was a great intro video.I found Your explanation easy to follow and understand!

[@Mrusama93]

Thanks ma'am i have never learnt ne555 ever like you told love you.

[@vmsrao2125]

Excellent explanation madam.Thank you very much

[@richardpayne9640]

I would have to put this to practical use to get this into my memory Thank you!

[@tcroyce8128]

Loved the presentation for the schematics.

[@jamesyount2423]

What she doesn't say is that discharge is also connected to threshold or trigger to cause timing. In her graphic it wouldn't do much but charge up a cap.

[@ShiftingDrifter]

Great job! Particularly the graphics illustrations and rapid technical explanation without any confusing filler. However, I think it would've been a nice touch to add a quick closing illustration of the 555 in action by demonstrating its use in a very simple circuit like an Astable Oscillator... just a little satisfying payoff for your audience. A happy ending as it were. ;)

[@GlynWilliams1950]

Very useful We call it Triple 5 (timer), in my area in Australia We also say 5k (for the resistor, five Kay), We are already metric so we understand 1K etc

[@PankajYadav-hr8tp]

Nice one ...super excited for the next episode ...now I can make my own clock...please explain by using a clock in the next video

[@mediocreman6323]

If you want to make a clock, use a quartz oscillator.

[@PankajYadav-hr8tp]

@@mediocreman6323 thanks for the reply ..but I want an alternative option also...let's do something new

[@mediocreman6323]

@@PankajYadav-hr8tp - Why? If you want a clock, a crystal-based oscillator is the way to go. You can cut bread with scissors, yes, but why not use a knife? Given the fact that ohmic resistance changes with temperature and even a 1% tolerance in capacity and resistance is a huge deal for a clock (problems a quartz does not have, by design) would make a 555-based clock pretty darn inaccurate. Sufficient for processor clocks or something I guess, but not for an actual clock.

[@PankajYadav-hr8tp]

@@mediocreman6323 well actually ,there is much more than the clock ,and it's a part of it...since the video was for education purpose, I guess the extra part will not be relevant.....and moreover the scissors are pretty much used than knife whenever you want to create something special than the usual work to do...

[@RobiBue]

@mediocre man: ok, scissors are two knives with a hinge, but the 555 is not made of two quartz oscillators, so if someone wants to use the 555 as a clock, there‘s nothing wrong with that. It is not necessarily going to be accurate, but even to cut bread, cutting it with a paring knife, or a chef knife, or even a Swiss Army knife is not going to give you the same result as cutting it with a bread knife, although either one of them is a knife... 🤪 ✌️

[@WistrelChianti]

nice explanation of the parts of the schematic and how the connect. Sadly that is all I got from it. Here's my problem though: A the start of the video I read that it is a "555 timer", so I assume it keeps time somehow. After watching, I understand that in fact it has functionality to compare voltages and weirdly contains an inverter when the Q pin could have been used to the same effect. The output of the compares goes into another thing. There are some pins too and I now know what they are connected to. An analogy would be if you showed me a washing machine in peices, but called it a motor car and explained that "this bit changes voltage levels" or "this bit spins" or "this bit pumps" then at the end said there are different modes. I'd have no idea what it did or how it worked.

[@ManiKandan-xb2yk]

Wonderful video but only at 6:33 you made a mistake. That pnp is connected to reset. Only Grounding it will turn on.

[@clayz1]

My one and only breadboard slash 555 timer electronics project. Has a battery, a pot, an on off switch and a variable time on off LED. Cool.

[@johnmarks714]

Awesome stuff. I hope you cover how the 6502 cpu works one day.

[@JoshuaPritt]

The Makers Local 256 makerspace used a 555 timer to make a soldering learning kit to build a board that "rolls" a 6 sided die made of LEDs. Pretty neat!

[@maker_karen1785]

Joshua Pritt I soldered a similar kit in the project episode that followed the overview of ICs. Though my kit used a phase locked loop IC and a binary ripple counter. Would be neat to see a similar circuit but with a 555 instead!

[@BertGrink]

Joshua Pritt That sounds quite interesting, you wouldn't happen to have a link to that, would you?

[@LeventeDaradici]

it is explained superbly! thanks and respect!

[@MrGato516]

Correct me if I am wrong, however there is a minor error: At minute 6:37 you state Q2 is off. A PNP is ON when the base is lower than the emitter. Additionally, the current limiting resistor should be placed between switch and Q2 base.

[@freddyfredrickson]

LOL I remember using this IC in electronics class in high school back in the 80s... It was the basis of so many TTL based circuits we made.

[@subhadeeproychowdhury1059]

Really good presentation

[@christopherbrown3614]

Thanks for the explanation!

[@gerrys6265]

Great explanation, thanks...except I am stuck on some point I obviously don't understand. sWhen the output is high (S is H) and Q bar then being low there is no power flowing to pin 3, so no power going to pin3 - even though one would think it would if there was power getting through the flipflop. When S is Low Q bar is high and although there is power flowing through the flipflop, does it not then (through its inverter) cut off the power to pin 3? So how/when does power get through to pin 3? Sorry for such a dumb (I think) question... Ahhh...I watched the next video and it became clear Thanks

[@Decco6306]

Thats the best internal diagram ive seen of a 555 yet

[@dangacoscosim]

Can you show a diagram using ic555 connected wit spdt relay, capacitor, potentiometer, and digital clock display?

[@clintestood5839]

Thanks for presentation

[@dennisk5818]

As a visual learner, I'd have to see what happens during operation. I understand the 555 in a very broad way, though. Great video. Maybe a bit slower.

[@briancoverstone4042]

Hi Karen. I have a question about the 555. Why take the output from Q bar and invert it, instead of just wiring Q to the output pin directly?

[@mediocreman6323]

I do not know if this applies to the 555 specifically, but you can use inverters to “clean up” the input, make signals that are below a certain threshold be a clean low and the ones which are above that threshold a clean high. But, as I said, I do not know if this particular inverter acts like such a trigger (Schmitt-trigger as far as I remember), if anybody could enlighten me, it would be highly appreciated.

[@maker_karen1785]

I don't really know. I didn't design the 555. [shrug] I'm sure there's a reason, but it is more advanced than my current knowledge.

[@curtispazderka1336]

One of the drawbacks of "conceptualising" circuits, is that it can make how they work apparent, but not why things were done that way. In an IC, you don't have a "flip-flop", you have a network of transistors. The transistor networks of all the conceptualised parts are joined together as one part. So whilst an "inverter" is known as a discrete component, in this IC it is just another couple of transistors. In this IC, the output of the flip-flop transistor network is not powered to drive the output pin; so either a buffer or an inverting buffer is required. Seeing as the inverted value is required internally, it makes sense to use the same flip-flop output to drive both signals.

[@harriusk4u]

Incredible lecture! Just have a question. What is the triangle attached to the output pin? Look like it inverts the !Q output.

[@maker_karen1785]

That's exactly what it is, an inverter.

[@ثامرالبياتي-ض3ه]

Please when we see for the circuit electronic .we make short between pins 4and 8 .while pin 4 it is pin of base of transtor .

[@khan691]

Excellent learning program 👍

[@chaaaaaaaaaaan]

instead of using an inverter, can’t we connect pin3 directly to Q?

[@jsims2985]

Very well done. Thanks so much!

[@chrisdaniousz]

MANTAP VIDEO NYA SALAM DARI MALAYSIA ,SARAWAK

[@bestbestchannelupcoming]

Thank you for the video.

[@shredder60]

Very well done

[@diyhouse]

Nice Video,... Ah an industry standard,... where would we be without the good old Signetics 555

[@thunderbird1454]

Hey Karen, does that old valve tektronix CRO in the background actually work and do you know how to drive it ????

[@anasasim3856]

Man you are soo good! Thank you!

[@javierguadarrama9405]

Thanks, You are an extraordinary woman.

[@ab_ab_c]

Wow.. Now that's a video that will have to be rewatched a few times to understand... A common use example circuit (e.g. voltage freq converter, freq modulation, etc) would have been useful. :-) Thanks for sharing!

[@josephmazzeo9413]

Nice presentation...you could get a PhD studying this circuit it is so versatile. The 555 should be in the chip Hall of Fame - a timeless timer chip. 5k+5k+5k = 555 nice! Good thing they didn't use 6k resistors LOL.

[@sushilchoudhary5749]

Very very thanks for informative video.

[@jacobbronson9947]

How does the cap charging on pin 7 trigger the reset?

[@dudipallabharathkumar5973]

Super explanation ..

[@birukgelan7032]

I have one request If have a chance to reply my question, do have a recommended book that help to build circuit project for 10 year kid, thanks

[@rul1175]

Do you need to know how the 555 works by memory or its something people don't memorize and just follow a schematic???

[@HS-eq3gk]

good video, easy to follow

[@RixtronixLAB]

Nice info, well done, thanks :)

[@michaelszczys8316]

I need a circuit to turn on a low power, low voltage device for about 2 seconds then turn off for about 10 seconds, repeat. Looks like this might be the thing. With my shaky understanding of electronic circuitry I hope I can build it.

[@sangarp2001]

i would like to know more about pin 4. It is PNP transistor. How it is on when it is connected to Vcc?

[@Designsbyg]

I guess I will have to watch this a few more times. I got lost pretty quick. If this is the simplest explanation, I may never get it.

[@dk3212]

I don't understand how the capacitor charging triggers the reset?

[@villagerse]

Charging and dischrgjng

[@Penguins247]

Good explanation; FWIW I thought the narration was at the correct speed. Anyone complaining can always use the speed controls to slow it down :)

[@rolengoldslick9053]

tech question how do i make a 555 timer do this: push button, wait 5 seconds, turn on a thing for 1 second, then power off/reset

[@madhupathiyil9251]

Good information 👍👍

[@JohnClulow]

Excellent tutorial !!

[@mohameddoudou3285]

it looks more easier than when it comes as an exercise in TD or exam

[@danielramirezcruz.2209]

Fantastic video great information l love it thanks for posting...

[@walkingrobin9965]

Why you have a d104 mic in back ground?

[@murrrr8288]

really good video, thanks!

[@gatosgataros2218]

My lcd screen has any if them or my gaming pc or phone ?

[@akkafietje137]

How can I be sure, that after only applying VCC, the flip/flop is in the reset mode ?

[@frankansari3457]

I played with this as a boy... This is so nostalgic.

[@irynathebeauty]

great explanation!

[@pbissell1]

I am disappointed to read some of the comments you have received, both here, and on other videos. I’m sorry you are subjected to their misogyny. I have subscribed.

[@vincentrobinette1507]

Why would they use an inverter on Q not, rather than using Q as the output? 2 reasons for the question, the discharge transistor is going to limit the output of Q not to the base-emitter junction voltage of the discharge transistor. It won't reach logic level, unless, there is a resistor to the base of the discharge transistor. The other thing is the unnecessary additional parts count, and propagation delay. The Reset input transistor is a PNP. Tying this transistors base to the positive rail, the same potential as it's emitter, turns the transistor OFF. Again, there has to be some resistance on either the base or the emitter of this transistor, or it will immediately blow out, if the Reset pin is tied down. (full supply current available to the base-emitter junction) I personally, haven't designed any circuits, where the reset pin isn't just simply tied to the positive rail. I just connect pins 4 and 8 together.

[@MrCardeso]

Thanks, Karen!

[@mrroobarb]

OK - great video (Dad speaking)... but we seemed to have jumped from basic electrical circuits to complex IC design. I was following this series with my 12 year old son who was beginning to grasp the basics and now feels he is falling behind as this has moved on far to fast. I'm having to explain that he's not stupid for not getting it... Lazy Dad has to go back to breadborads and blinky sketches ;-)

[@maker_karen1785]

Bruce Morgan what do you feel that I skipped? I think I covered all the basic components. Simple ICs seemed liked the next logical step. (No pun intended.) I’m not sure where else I could have gone next. What do you think?

[@dibblethwaite]

Just little bit too fast I think

[@Palmit_]

soo... how does it count or countdown?

[@roneyalbirto6667]

keep up the great work . you are awesome

[@ommpeter]

Thanks

[@arduino5267]

Thank you very much

[@Notmy00000]

C1 and c2 are opamps.?

[@ryzen980]

What happens if the timer outputs "Invalid"? How will it effect the timing?

[@geraldolici1358]

But why is R above S in the flip-flop used in 555 timers. And don't 555 timers use active-low flip-flops?

[@robertmartin5679]

Please do How 7555 timers work :)

[@sefalibhakat143]

Very good graphic 🤗🤗🤗

[@cheewurz]

Well Done!

[@shyamaprasadbasu1844]

Excited to get the next vedio