9 ms·

555 Timer Circuits

286 points by okl 2y ago

tahoupt 2y ago
Shout out to Forest M Mims III, the OG 555 circuit guru.https://en.wikipedia.org/wiki/Forrest_Mims https://en.wikipedia.org/wiki/Forrest_Mims
- stonethrowaway 2y ago
  He’s working on a new book that attempts to disprove evolution or at least show cases to the contrary, advocating for a grand design as a primary mechanism instead. Curious to read it, I’m hopeful he will release it.
  - Mistletoe 2y ago
    Also a global warming denier. I’d love to see him explain how this is wrong? https://climate.nasa.gov/vital-signs/global-temperature/?intent=121 https://climate.nasa.gov/vital-signs/global-temperature/?int...
    - stonethrowaway 2y ago
      Your comment appears grey to me so I assume someone downvoted you? How strange. At any rate, I do own his books on electronics as a kind of an amusing look into the history of how electronics were taught, but I do find it to be a positive thing in the world to have curious individuals like himself. People from all walks of life believe all sorts of kooky shit. That’s the spice of it I suppose.
  - nickpsecurity 2y ago
    You might enjoy this article which lists all the articles of faith evolutionists believe in: https://answersingenesis.org/theory-of-evolution/12-the-basic-assumptions-of-evolution/ https://answersingenesis.org/theory-of-evolution/12-the-basi... My biggest critiques are that it consistently fails its predictions. You’d see an endless stream of intermediate forms going in so many directions. Instead, we saw few if any, nature organized more hierarchically, and organisms just appear out of thin air after extinctions (eg Cambrian Explosion). Instead of falsification, scientists keep making excuses for it like it is a religion that can’t be wrong. I’ll add that humans have observed creatures, in their areas and in captivity, for a long time. We haven’t seen the chickens start giving birth to different animals. I’m grateful the fire ants and poisonous spiders we’re dodging haven’t turned into something more effective. Dumb evolution would have a crazy number of adaptation streams happening, many attempts per species, to create all the life we see. Instead, we see exactly zero movement from one kind of animal to another with changes only happening within kinds. Whereas, studies of creation itself have proven the opposite. Everything from our non-life experiments to evolutionary algorithms show a creator who fine tunes is necessary. The universe itself has many constants that never change, they work together in precise ways, all has perfect reliability, and life on Earth depends on most of them. Complexity of most of biology is such that we’re incapable of manufacturing it. (See a lung vs a respirator.) It only gets more and more impossible over time the more we learned. On time scales (X is millions of years old), they seem to assume the Earth didn’t change much at all over a long period of time. A specific thing changes at rate X. They’ll roll the clock back that much until they hit a point in their theory. Both human literature (esp Genesis) and the fossil record show catastrophes with huge effects on the Earth. It probably went through many changes. So, all time estimates that make that assumption are faith-based, likely-incorrect beliefs no matter how many textbooks they end up in. There is a minority studying Catastrophism or something like that to understand their effect. Finally, godless science that broke from Christian scientists, like Newton and Pascal, all backed David Hume saying only material, observable things exist. Nothing else is ever allowed in scientific theory. A faith-based, unproven belief. While still making godless and materialism axiomatic, the same scientists tell us of a world outside our universe, exceeding the laws of physics, and maybe even having effects on observed phenomenon. Instead of things with evidence (eg Bible), they’ve shifted to purely-imaginary constructs outside the universe to support their claims which themselves contradict the Hume foundation they demand of us. They do it while denying the logical implications of the complexity and fine-tuning we’ve observed. Those are some examples of counters to mainstream creation, like evolution and long timescales, being a pile of faith-based dogma that continues to fail in scientific experiments, historical writings, complexity theory, and global observations by laypeople. Outside of minor adaptation, evolution theory is provably false which leaves God as the primary hypothesis. From there, we consider whichever God claim has the most evidence and impact. That’s Jesus Christ. :)
buildsjets 2y ago
Built many a 555 timer circuit back in the day! But in modern times, I can get an ATMega328p already attached to a PC board for $2.50 and load code on it to do whatever I want, including blink a red LED.
- tdeck 2y ago
  Not only are cheap microcontrollers often an easier choice for things the NE555 might be used for, they often draw far less power as well. I personally prefer to use an even smaller and cheaper micro like the ATTiny13A. It's also worth noting that your traditional 555 timers don't like to run below 5V, for that you'll need something like an LMC555. If you're building up a parts inventory, it often makes sense to have a bunch of very cheap micros rather than special purpose parts.
  - Joel_Mckay 2y ago
    Could always use a 555 as a charge pump for your micro power mcu too. Indeed, a small $0.23 mcu may have its own internal RC oscillator, or even a MEMS based resonator on a PLL. =3
  - dragontamer 2y ago
    The main advantage of 555 timer is that it is configured with a resistor/capacitor kit. No computer or programming required. Microcontrollers obviously have more than 1 bit of memory + 2x analog comparators + one 33% / 66% voltage divider (which is all a 555 timer truly is). What is surprising however is how flexible 1 bit of memory + 2x analog comparators + one 33% / 66% voltage divider
    - tdeck 2y ago
      Another way of looking at it is the 555 is useless without multiple extra parts, where as most MCUs can operate with only a bypass cap (and even that is often optional in practice). But you do have to buy a programmer ($5 these days) and get comfortable with firmware, which puts some analog folks off. I'll admit that there is a certain elegance and appeal to using only parts you fully understand and nothing extraneous.
tdeck 2y ago
Here's my tip for the 555 timer: Learn what's inside it! As you can see on the "Inside the 555" page, there are fewer than 10 functional components inside and three of them are resistors. For some reason I always struggled to remember the different operating mode configurations, what they are called, and how to set them up. But one day I was trying to build a specific thing and decided to sit down and actually understand the 555. To my surprise, it's really simple in operation and requires relatively little electronics theory to understand and derive the different configurations yourself. Once I did that, I haven't forgotten it and I can come up with more creative uses for the 555.
- 082349872349872 2y ago
  You might be interested in http://www.designinganalogchips.com http://www.designinganalogchips.com ...
  - tdeck 2y ago
    Thanks, I hadn't heard of this book and will definitely check it out!
- gus_massa 2y ago
  Another link about the internal pars of the 555 https://www.righto.com/2016/04/teardown-of-cmos-555-timer-chip-how.html https://www.righto.com/2016/04/teardown-of-cmos-555-timer-ch...
- Stratoscope 2y ago
  The Evil Mad Scientist kits are a great way to learn what's inside it. They are faithful replicas of the internal 555 circuitry, built with discrete transistors and resistors. You mentioned only ten functional components inside it, but if you look at individual transistors and resistors, there are quite a few more. Here is the through-hole component version: https://shop.evilmadscientist.com/productsmenu/652 https://shop.evilmadscientist.com/productsmenu/652 And a surface mount device version: https://shop.evilmadscientist.com/productsmenu/922 https://shop.evilmadscientist.com/productsmenu/922 I built the through-hole version, and it worked the first time I wired up a circuit around it. Highly recommended!
JKCalhoun 2y ago
I love the circuits on this site (1). Kind of quirky layout (pretty sure the parent page uses "frames") but has fifty 555 circuits as well as 100+ transistor circuits, etc on the site. Def a labor of love. (Buy the CD, ha ha.) 1) https://www.talkingelectronics.com/projects/50%20-%20555%20Circuits/50%20-%20555%20Circuits.html https://www.talkingelectronics.com/projects/50%20-%20555%20C...
cpldcpu 2y ago
Well, you can also build microprocessors out of them: https://hackaday.io/project/182915-555enabled-microprocessor https://hackaday.io/project/182915-555enabled-microprocessor
doe_eyes 2y ago
In some respects, it's a testament to how much the world of electronics has changed over the past ~25 years. It used to be that 555 was this Swiss-army-knife IC that you had to learn about. Multiple people published entire books about it! Today, it's essentially obsolete. You're quite unlikely to find it in any competently-done commercial designs. Every analog trick you can do with it can be done more cheaply, more reliably, with better power efficiency, and with fewer external components using a modern MCU. It's not that analog is dead, but it's solving different problems now. Including how to keep ultra-high-speed digital signals usable within the footprint of a PCB - which wasn't that much of a consideration in the golden days of the 555.
- theamk 2y ago
  There is still at least one niche for it: very simple circuits which requires >5v. Using 555 lets you skip the regulator and drivers. But even there, it's high Iq limits its applicability.
  - 01100011 2y ago
    I'd guess that a 555 is also tougher than a microcontroller. I'm putting together an HV supply and thought about using a microcontroller but opted for a 555-based oscillator. Either one won't survive HV but I think the 555 will handle stray charges better.
    - K0balt 2y ago
      Modern mucus are surprisingly fault tolerant. Just saying. It’s not like the bad old days where if you sneezed at a cmos chip it would probably be fried. I’m not sure how that stacks up to a 555 though.
      - 01100011 2y ago
        My mucus is about as fault tolerant as it ever has been. Sometimes it gets really thick if the weather is dry or I'm sick, but otherwise I haven't noticed any difference. I find that drinking water helps.
II2II 2y ago
Plenty of people are commenting on how modern microcontrollers are better than the 555. I agree, with a caveat: the 555 is a great learning tool. It is complex enough to be interesting, yet simple enough to be well understood. It is easy to clip an oscilloscope to it's pins to have a visual representation of how its inputs affects its outputs. It is a stepping stone that helps people learn how to build more complex circuits. Much as some software developers have to understand assembly language to build the most fundamental bits of software (e.g. compilers), some people have need to understand electronics to build the most fundamental bits of hardware.
- FooBarBizBazz 2y ago
  I always found DACs/IO to be the limiting thing with microcontrollers. That and latency in general. When you were doing analog stuff with op-amps, yeah, you were setting yourself up for other problems like thermal drift, but there was never any worry that you were going to run out of capacity like you would switching tasks on a microcontroller, and latency was negligible. Plus there weren't many wires and you could see it on a scope. It was all satisfyingly immediate. I wonder what kind of cheap and ubiquitous DSPs(?) people use for that kind of niche nowadays, to do it digitally(?). Do they string DACs together on a bus somehow? How do you get, say, signals flowing around at a couple hundred kHz sample rates, with nice dataflow parallelism -- and then get those signals out to actuators, without much latency -- in that world? Like, what would you use to mix a bunch of audio and run some IIR filters with 20ns latency? Or control, say, four motors with, I dunno, 1 kHz bandwidth? I get this feeling that DACs remain a bottleneck and you're rapidly looking at expensive stuff to do that with a microcontroller, but maybe I'm wrong; I don't do this stuff.
  - Neywiny 2y ago
    As an FPGA developer: much agreed. We know exactly what's happening every clock cycle (or at least can), and often are able to have extremely deterministic computation. You can do this on micros, but anything with good performance will have some caching, maybe context switching, etc. The polarfire SoC marketing has a graph showing either determinism or performance (I can dig it up if interested). In FPGA land, we define the pipelining such that we get both. I usually go out to an RFIC then stop caring, but you can calculate the latencies the as well.
reader9274 2y ago
Might be interested to check out this legendary book: https://en.m.wikipedia.org/wiki/The_Art_of_Electronics https://en.m.wikipedia.org/wiki/The_Art_of_Electronics
lmpdev 2y ago
We sell kits with plenty of 555 timers (including some listed here) It’s a shame that Arduino has effectively truncated kids learning with a full MCU as the “building block” of their learning I see it also bite them in the arse with wasteful solutions. Often a BJT or power fet is all they need (say for a basic relay trigger). But if they aren’t presented with a shiny arduino compatible module explicitly designed for what they want, they get nervous About half the kids I see make the intellectual jump, half end up not coming back I do wish kids were taught basic soldering, it would make the learning process a lot less worrisome The 555 and LM741 are still supreme learning tools. They are even simple enough to breadboard out with BJTs and analogue components. I’ve only seen a few extremely hardcore guys bother to conceptualise under the hood that deeply
- doe_eyes 2y ago
  > It’s a shame that Arduino has effectively truncated kids learning with a full MCU as the “building block” of their learning Why? I think the vast majority of hobbyists used the 555 as a "black-box" chip. They now have a more intuitive, cheaper, and more power-efficient way of doing the same thing. Pre-Arduino, learning electronics wasn't more profound. It was just less accessible. Nowadays, you have the same number of determined and talented hobbyists who eventually master some of the more arcane topics. You also have more people who learn just enough to get their art project done, and it's easier than it used to be... but why is that a bad thing? There's a temptation to demand that others do things the hard way just because we had to. But is it healthy? I don't lament the demise of the 555 any more than I lament that the youth no longer knows how to put shoes on a horse.
  - giantrobot 2y ago
    > There's a temptation to demand that others do things the hard way just because we had to. But is it healthy? I don't lament the demise of the 555 any more than I lament that the youth no longer knows how to put shoes on a horse. I agree with both you and the GP. Arduinos tend to make goofing around with electronics more accessible to more people. At the same time a lot of projects could be built very simply with just a couple timer chips. It's unfortunate people reach for a relatively complex solution (Arduino etc) to what's ultimately a simple problem. They would benefit a great deal from just knowing a blinking light can be made very simply with a simple circuit.
ChrisMarshallNY 2y ago
Holy cow. Those things are still around? I cut my teeth on them, about 40 years ago.
pugworthy 2y ago
Clark Zapper… Hmm sure offers some interesting properties! > This device is used tocure, treat and prevent any disease. It will cure anything. https://www.555-timer-circuits.com/clark-zapper.html https://www.555-timer-circuits.com/clark-zapper.html
skinwill 2y ago
The internal diagram appears to be incorrect, https://www.555-timer-circuits.com/inside-the-555.html https://www.555-timer-circuits.com/inside-the-555.html The internal resistors should be connected to the upper comparator. Also, that diagram just seems confusing. Something like this makes more sense: https://www.theengineeringknowledge.com/wp-content/uploads/2020/09/Internal-diagram-of-a-555-integrated.jpg https://www.theengineeringknowledge.com/wp-content/uploads/2...
moffkalast 2y ago
> VCC +4.5 to 15V With everything going 3.3V these days with no 5V tolerance (can't have nice things ofc), is there some kind of 333 timer that would do the same job but down to those logic levels?
- kilpikaarna 2y ago
  LMC555
wkjagt 2y ago
I recently used a 555 (and some other simple parts) to fix some timing issue my ham radio's internal CW keyer seemed to be having. Maybe I could have used an ESP32 module that I also had lying around, but I could run the 555 directly off of the ~12 volt power supply, and it was also more fun to build the little circuit. More details if curious: https://www.reddit.com/r/amateurradio/comments/1eo9ki7/xiegy_g90_cw_keyer_skipping_dits_fixed_with_a_555/ https://www.reddit.com/r/amateurradio/comments/1eo9ki7/xiegy...
peter_retief 2y ago
Probably the first IC I used.
wkjagt 2y ago
The awesome Ben Eater gives the clearest explanation I've seen of how the 555 timer works internally: https://www.youtube.com/watch?v=kRlSFm519Bo https://www.youtube.com/watch?v=kRlSFm519Bo
timonoko 2y ago
Apropos. I made TV-surveillance unit when 555 was almost brand new. Maybe 1977. The start of a picture was long negative pulse, easy to recognize with 555, which triggered second 555, which triggered third 555 in unison with the horizontal scan pulse. Thus you had fairly accurate point selected in the screen, showing a dot, while camera info was sampled and compared to a preset value. Thus the watchmen could use few knobs and select a point in the screen, which would raise an alarm when illumination changed. Because it was so cheap, you could select multiple triggering points. No fancy microprocessors this time, which were too slow anyways.
- qwertygnu 2y ago
  Whoa that's a really cool application! Another example of limitations begetting creativity.
- sitkack 2y ago
  Thats awesome! You could make it so you could control it with a light pen. It would integrate over a window of a single scan line? A slightly more complex device could retrigger and sum into a bucket brigade and integrate over a region.
0xTJ 2y ago
I find the pin description and internal schematic a bit lacking on this website. Pin 5 isn't shown internally connected to the voltage divider, and is simply described as "affecting the timing".
JuanTono 2y ago
The NE555 helped me get my first tech job in high school after I gave a presentation at a Nodebots community meetup. (It also, in some way, helped me land a job at Texas Instruments while I was in university during the COVID pandemic.) It was also the focus of the first tutorial I made for Instructables a few years ago. I always remember it fondly.
relwin 2y ago
Without the 555 how can we have such fun make contests? The original www.555contest.com by Chris Gammell and Jeri Ellsworth (2011) had a tremendous response. 11 years later Hackaday held one with very creative entries. If you enter a contest you'll be forced out of your comfort zone (programming with solder) and will appreciate MCU's even more when you're done! If you're lucky you'll get a phone call from (the late) Hans Camenzind as I did in 2011. And maybe you'll invent something goofy, like "Le Dominoux": https://youtu.be/PQOjkuJtBfM?si=Np2MSKgAp4ULwzcl https://youtu.be/PQOjkuJtBfM?si=Np2MSKgAp4ULwzcl
squarefoot 2y ago
I'm probably being unpopular writing this, but I never quite liked the 555. Not diminishing its value and the ingenuity that went into its design; I rather found myself much more attracted by CMOS gates, also in analog circuits. One day I was playing with PLLs and to better understand how phase detectors work, I built a proof of concept motion detector off a single quad xor chip (4030 probably), 1st gate working as ultrasound oscillator connected to a tx capsule, 2nd one biased as linear amplifier with input connected to a rx capsule, 3rd gate working as phase detector taking both 1 and 2 gates outputs, 4th gate driving a LED, which would flash every time I moved the hand in front of the capsules as I was delaying one of the two signals, which triggered the gate. Very fun and instructional. The interesting part is that a CMOS digital gate can become a decent linear amplifier if properly biased, not unlike more common opamps, so where high linearity or fidelity in audio signals aren't a must, it can be quite an interesting part. As an example, here's a equalizer built around a 4049 quad inverter gate chip. http://www.runoffgroove.com/mreq.html http://www.runoffgroove.com/mreq.html As for digital gates, I couldn't recommend more the TTL and CMOS cookbooks by Don Lancaster: they're a goldmine of ideas. 2nd one is available for free at author's site. https://www.tinaja.com/ebooks/cmoscb.pdf https://www.tinaja.com/ebooks/cmoscb.pdf

286 points by okl 2y ago

Shout out to Forest M Mims III, the OG 555 circuit guru.https://en.wikipedia.org/wiki/Forrest_Mims https://en.wikipedia.org/wiki/Forrest_Mims

stonethrowaway 2y ago
He’s working on a new book that attempts to disprove evolution or at least show cases to the contrary, advocating for a grand design as a primary mechanism instead. Curious to read it, I’m hopeful he will release it.
- Mistletoe 2y ago
  Also a global warming denier. I’d love to see him explain how this is wrong? https://climate.nasa.gov/vital-signs/global-temperature/?intent=121 https://climate.nasa.gov/vital-signs/global-temperature/?int...
  - stonethrowaway 2y ago
    Your comment appears grey to me so I assume someone downvoted you? How strange. At any rate, I do own his books on electronics as a kind of an amusing look into the history of how electronics were taught, but I do find it to be a positive thing in the world to have curious individuals like himself. People from all walks of life believe all sorts of kooky shit. That’s the spice of it I suppose.
- nickpsecurity 2y ago
  You might enjoy this article which lists all the articles of faith evolutionists believe in: https://answersingenesis.org/theory-of-evolution/12-the-basic-assumptions-of-evolution/ https://answersingenesis.org/theory-of-evolution/12-the-basi... My biggest critiques are that it consistently fails its predictions. You’d see an endless stream of intermediate forms going in so many directions. Instead, we saw few if any, nature organized more hierarchically, and organisms just appear out of thin air after extinctions (eg Cambrian Explosion). Instead of falsification, scientists keep making excuses for it like it is a religion that can’t be wrong. I’ll add that humans have observed creatures, in their areas and in captivity, for a long time. We haven’t seen the chickens start giving birth to different animals. I’m grateful the fire ants and poisonous spiders we’re dodging haven’t turned into something more effective. Dumb evolution would have a crazy number of adaptation streams happening, many attempts per species, to create all the life we see. Instead, we see exactly zero movement from one kind of animal to another with changes only happening within kinds. Whereas, studies of creation itself have proven the opposite. Everything from our non-life experiments to evolutionary algorithms show a creator who fine tunes is necessary. The universe itself has many constants that never change, they work together in precise ways, all has perfect reliability, and life on Earth depends on most of them. Complexity of most of biology is such that we’re incapable of manufacturing it. (See a lung vs a respirator.) It only gets more and more impossible over time the more we learned. On time scales (X is millions of years old), they seem to assume the Earth didn’t change much at all over a long period of time. A specific thing changes at rate X. They’ll roll the clock back that much until they hit a point in their theory. Both human literature (esp Genesis) and the fossil record show catastrophes with huge effects on the Earth. It probably went through many changes. So, all time estimates that make that assumption are faith-based, likely-incorrect beliefs no matter how many textbooks they end up in. There is a minority studying Catastrophism or something like that to understand their effect. Finally, godless science that broke from Christian scientists, like Newton and Pascal, all backed David Hume saying only material, observable things exist. Nothing else is ever allowed in scientific theory. A faith-based, unproven belief. While still making godless and materialism axiomatic, the same scientists tell us of a world outside our universe, exceeding the laws of physics, and maybe even having effects on observed phenomenon. Instead of things with evidence (eg Bible), they’ve shifted to purely-imaginary constructs outside the universe to support their claims which themselves contradict the Hume foundation they demand of us. They do it while denying the logical implications of the complexity and fine-tuning we’ve observed. Those are some examples of counters to mainstream creation, like evolution and long timescales, being a pile of faith-based dogma that continues to fail in scientific experiments, historical writings, complexity theory, and global observations by laypeople. Outside of minor adaptation, evolution theory is provably false which leaves God as the primary hypothesis. From there, we consider whichever God claim has the most evidence and impact. That’s Jesus Christ. :)

buildsjets 2y ago

Built many a 555 timer circuit back in the day! But in modern times, I can get an ATMega328p already attached to a PC board for $2.50 and load code on it to do whatever I want, including blink a red LED.

tdeck 2y ago
Not only are cheap microcontrollers often an easier choice for things the NE555 might be used for, they often draw far less power as well. I personally prefer to use an even smaller and cheaper micro like the ATTiny13A. It's also worth noting that your traditional 555 timers don't like to run below 5V, for that you'll need something like an LMC555. If you're building up a parts inventory, it often makes sense to have a bunch of very cheap micros rather than special purpose parts.
- Joel_Mckay 2y ago
  Could always use a 555 as a charge pump for your micro power mcu too. Indeed, a small $0.23 mcu may have its own internal RC oscillator, or even a MEMS based resonator on a PLL. =3
- dragontamer 2y ago
  The main advantage of 555 timer is that it is configured with a resistor/capacitor kit. No computer or programming required. Microcontrollers obviously have more than 1 bit of memory + 2x analog comparators + one 33% / 66% voltage divider (which is all a 555 timer truly is). What is surprising however is how flexible 1 bit of memory + 2x analog comparators + one 33% / 66% voltage divider
  - tdeck 2y ago
    Another way of looking at it is the 555 is useless without multiple extra parts, where as most MCUs can operate with only a bypass cap (and even that is often optional in practice). But you do have to buy a programmer ($5 these days) and get comfortable with firmware, which puts some analog folks off. I'll admit that there is a certain elegance and appeal to using only parts you fully understand and nothing extraneous.

tdeck 2y ago

Here's my tip for the 555 timer: Learn what's inside it! As you can see on the "Inside the 555" page, there are fewer than 10 functional components inside and three of them are resistors. For some reason I always struggled to remember the different operating mode configurations, what they are called, and how to set them up. But one day I was trying to build a specific thing and decided to sit down and actually understand the 555. To my surprise, it's really simple in operation and requires relatively little electronics theory to understand and derive the different configurations yourself. Once I did that, I haven't forgotten it and I can come up with more creative uses for the 555.

082349872349872 2y ago
You might be interested in http://www.designinganalogchips.com http://www.designinganalogchips.com ...
- tdeck 2y ago
  Thanks, I hadn't heard of this book and will definitely check it out!
gus_massa 2y ago
Another link about the internal pars of the 555 https://www.righto.com/2016/04/teardown-of-cmos-555-timer-chip-how.html https://www.righto.com/2016/04/teardown-of-cmos-555-timer-ch...
Stratoscope 2y ago
The Evil Mad Scientist kits are a great way to learn what's inside it. They are faithful replicas of the internal 555 circuitry, built with discrete transistors and resistors. You mentioned only ten functional components inside it, but if you look at individual transistors and resistors, there are quite a few more. Here is the through-hole component version: https://shop.evilmadscientist.com/productsmenu/652 https://shop.evilmadscientist.com/productsmenu/652 And a surface mount device version: https://shop.evilmadscientist.com/productsmenu/922 https://shop.evilmadscientist.com/productsmenu/922 I built the through-hole version, and it worked the first time I wired up a circuit around it. Highly recommended!

JKCalhoun 2y ago

I love the circuits on this site (1). Kind of quirky layout (pretty sure the parent page uses "frames") but has fifty 555 circuits as well as 100+ transistor circuits, etc on the site. Def a labor of love. (Buy the CD, ha ha.) 1) https://www.talkingelectronics.com/projects/50%20-%20555%20Circuits/50%20-%20555%20Circuits.html https://www.talkingelectronics.com/projects/50%20-%20555%20C...

cpldcpu 2y ago

Well, you can also build microprocessors out of them: https://hackaday.io/project/182915-555enabled-microprocessor https://hackaday.io/project/182915-555enabled-microprocessor

doe_eyes 2y ago

In some respects, it's a testament to how much the world of electronics has changed over the past ~25 years. It used to be that 555 was this Swiss-army-knife IC that you had to learn about. Multiple people published entire books about it! Today, it's essentially obsolete. You're quite unlikely to find it in any competently-done commercial designs. Every analog trick you can do with it can be done more cheaply, more reliably, with better power efficiency, and with fewer external components using a modern MCU. It's not that analog is dead, but it's solving different problems now. Including how to keep ultra-high-speed digital signals usable within the footprint of a PCB - which wasn't that much of a consideration in the golden days of the 555.

theamk 2y ago
There is still at least one niche for it: very simple circuits which requires >5v. Using 555 lets you skip the regulator and drivers. But even there, it's high Iq limits its applicability.
- 01100011 2y ago
  I'd guess that a 555 is also tougher than a microcontroller. I'm putting together an HV supply and thought about using a microcontroller but opted for a 555-based oscillator. Either one won't survive HV but I think the 555 will handle stray charges better.
  - K0balt 2y ago
    Modern mucus are surprisingly fault tolerant. Just saying. It’s not like the bad old days where if you sneezed at a cmos chip it would probably be fried. I’m not sure how that stacks up to a 555 though.
    - 01100011 2y ago
      My mucus is about as fault tolerant as it ever has been. Sometimes it gets really thick if the weather is dry or I'm sick, but otherwise I haven't noticed any difference. I find that drinking water helps.

II2II 2y ago

Plenty of people are commenting on how modern microcontrollers are better than the 555. I agree, with a caveat: the 555 is a great learning tool. It is complex enough to be interesting, yet simple enough to be well understood. It is easy to clip an oscilloscope to it's pins to have a visual representation of how its inputs affects its outputs. It is a stepping stone that helps people learn how to build more complex circuits. Much as some software developers have to understand assembly language to build the most fundamental bits of software (e.g. compilers), some people have need to understand electronics to build the most fundamental bits of hardware.

FooBarBizBazz 2y ago
I always found DACs/IO to be the limiting thing with microcontrollers. That and latency in general. When you were doing analog stuff with op-amps, yeah, you were setting yourself up for other problems like thermal drift, but there was never any worry that you were going to run out of capacity like you would switching tasks on a microcontroller, and latency was negligible. Plus there weren't many wires and you could see it on a scope. It was all satisfyingly immediate. I wonder what kind of cheap and ubiquitous DSPs(?) people use for that kind of niche nowadays, to do it digitally(?). Do they string DACs together on a bus somehow? How do you get, say, signals flowing around at a couple hundred kHz sample rates, with nice dataflow parallelism -- and then get those signals out to actuators, without much latency -- in that world? Like, what would you use to mix a bunch of audio and run some IIR filters with 20ns latency? Or control, say, four motors with, I dunno, 1 kHz bandwidth? I get this feeling that DACs remain a bottleneck and you're rapidly looking at expensive stuff to do that with a microcontroller, but maybe I'm wrong; I don't do this stuff.
- Neywiny 2y ago
  As an FPGA developer: much agreed. We know exactly what's happening every clock cycle (or at least can), and often are able to have extremely deterministic computation. You can do this on micros, but anything with good performance will have some caching, maybe context switching, etc. The polarfire SoC marketing has a graph showing either determinism or performance (I can dig it up if interested). In FPGA land, we define the pipelining such that we get both. I usually go out to an RFIC then stop caring, but you can calculate the latencies the as well.

reader9274 2y ago

Might be interested to check out this legendary book: https://en.m.wikipedia.org/wiki/The_Art_of_Electronics https://en.m.wikipedia.org/wiki/The_Art_of_Electronics

lmpdev 2y ago

We sell kits with plenty of 555 timers (including some listed here) It’s a shame that Arduino has effectively truncated kids learning with a full MCU as the “building block” of their learning I see it also bite them in the arse with wasteful solutions. Often a BJT or power fet is all they need (say for a basic relay trigger). But if they aren’t presented with a shiny arduino compatible module explicitly designed for what they want, they get nervous About half the kids I see make the intellectual jump, half end up not coming back I do wish kids were taught basic soldering, it would make the learning process a lot less worrisome The 555 and LM741 are still supreme learning tools. They are even simple enough to breadboard out with BJTs and analogue components. I’ve only seen a few extremely hardcore guys bother to conceptualise under the hood that deeply

doe_eyes 2y ago
> It’s a shame that Arduino has effectively truncated kids learning with a full MCU as the “building block” of their learning Why? I think the vast majority of hobbyists used the 555 as a "black-box" chip. They now have a more intuitive, cheaper, and more power-efficient way of doing the same thing. Pre-Arduino, learning electronics wasn't more profound. It was just less accessible. Nowadays, you have the same number of determined and talented hobbyists who eventually master some of the more arcane topics. You also have more people who learn just enough to get their art project done, and it's easier than it used to be... but why is that a bad thing? There's a temptation to demand that others do things the hard way just because we had to. But is it healthy? I don't lament the demise of the 555 any more than I lament that the youth no longer knows how to put shoes on a horse.
- giantrobot 2y ago
  > There's a temptation to demand that others do things the hard way just because we had to. But is it healthy? I don't lament the demise of the 555 any more than I lament that the youth no longer knows how to put shoes on a horse. I agree with both you and the GP. Arduinos tend to make goofing around with electronics more accessible to more people. At the same time a lot of projects could be built very simply with just a couple timer chips. It's unfortunate people reach for a relatively complex solution (Arduino etc) to what's ultimately a simple problem. They would benefit a great deal from just knowing a blinking light can be made very simply with a simple circuit.

ChrisMarshallNY 2y ago

Holy cow. Those things are still around? I cut my teeth on them, about 40 years ago.

pugworthy 2y ago

Clark Zapper… Hmm sure offers some interesting properties! > This device is used tocure, treat and prevent any disease. It will cure anything. https://www.555-timer-circuits.com/clark-zapper.html https://www.555-timer-circuits.com/clark-zapper.html

skinwill 2y ago

The internal diagram appears to be incorrect, https://www.555-timer-circuits.com/inside-the-555.html https://www.555-timer-circuits.com/inside-the-555.html The internal resistors should be connected to the upper comparator. Also, that diagram just seems confusing. Something like this makes more sense: https://www.theengineeringknowledge.com/wp-content/uploads/2020/09/Internal-diagram-of-a-555-integrated.jpg https://www.theengineeringknowledge.com/wp-content/uploads/2...

moffkalast 2y ago

> VCC +4.5 to 15V With everything going 3.3V these days with no 5V tolerance (can't have nice things ofc), is there some kind of 333 timer that would do the same job but down to those logic levels?

kilpikaarna 2y ago
LMC555

wkjagt 2y ago

I recently used a 555 (and some other simple parts) to fix some timing issue my ham radio's internal CW keyer seemed to be having. Maybe I could have used an ESP32 module that I also had lying around, but I could run the 555 directly off of the ~12 volt power supply, and it was also more fun to build the little circuit. More details if curious: https://www.reddit.com/r/amateurradio/comments/1eo9ki7/xiegy_g90_cw_keyer_skipping_dits_fixed_with_a_555/ https://www.reddit.com/r/amateurradio/comments/1eo9ki7/xiegy...

peter_retief 2y ago

Probably the first IC I used.

wkjagt 2y ago

The awesome Ben Eater gives the clearest explanation I've seen of how the 555 timer works internally: https://www.youtube.com/watch?v=kRlSFm519Bo https://www.youtube.com/watch?v=kRlSFm519Bo

timonoko 2y ago

Apropos. I made TV-surveillance unit when 555 was almost brand new. Maybe 1977. The start of a picture was long negative pulse, easy to recognize with 555, which triggered second 555, which triggered third 555 in unison with the horizontal scan pulse. Thus you had fairly accurate point selected in the screen, showing a dot, while camera info was sampled and compared to a preset value. Thus the watchmen could use few knobs and select a point in the screen, which would raise an alarm when illumination changed. Because it was so cheap, you could select multiple triggering points. No fancy microprocessors this time, which were too slow anyways.

qwertygnu 2y ago
Whoa that's a really cool application! Another example of limitations begetting creativity.
sitkack 2y ago
Thats awesome! You could make it so you could control it with a light pen. It would integrate over a window of a single scan line? A slightly more complex device could retrigger and sum into a bucket brigade and integrate over a region.

0xTJ 2y ago

I find the pin description and internal schematic a bit lacking on this website. Pin 5 isn't shown internally connected to the voltage divider, and is simply described as "affecting the timing".

JuanTono 2y ago

The NE555 helped me get my first tech job in high school after I gave a presentation at a Nodebots community meetup. (It also, in some way, helped me land a job at Texas Instruments while I was in university during the COVID pandemic.) It was also the focus of the first tutorial I made for Instructables a few years ago. I always remember it fondly.

relwin 2y ago

Without the 555 how can we have such fun make contests? The original www.555contest.com by Chris Gammell and Jeri Ellsworth (2011) had a tremendous response. 11 years later Hackaday held one with very creative entries. If you enter a contest you'll be forced out of your comfort zone (programming with solder) and will appreciate MCU's even more when you're done! If you're lucky you'll get a phone call from (the late) Hans Camenzind as I did in 2011. And maybe you'll invent something goofy, like "Le Dominoux": https://youtu.be/PQOjkuJtBfM?si=Np2MSKgAp4ULwzcl https://youtu.be/PQOjkuJtBfM?si=Np2MSKgAp4ULwzcl

squarefoot 2y ago

I'm probably being unpopular writing this, but I never quite liked the 555. Not diminishing its value and the ingenuity that went into its design; I rather found myself much more attracted by CMOS gates, also in analog circuits. One day I was playing with PLLs and to better understand how phase detectors work, I built a proof of concept motion detector off a single quad xor chip (4030 probably), 1st gate working as ultrasound oscillator connected to a tx capsule, 2nd one biased as linear amplifier with input connected to a rx capsule, 3rd gate working as phase detector taking both 1 and 2 gates outputs, 4th gate driving a LED, which would flash every time I moved the hand in front of the capsules as I was delaying one of the two signals, which triggered the gate. Very fun and instructional. The interesting part is that a CMOS digital gate can become a decent linear amplifier if properly biased, not unlike more common opamps, so where high linearity or fidelity in audio signals aren't a must, it can be quite an interesting part. As an example, here's a equalizer built around a 4049 quad inverter gate chip. http://www.runoffgroove.com/mreq.html http://www.runoffgroove.com/mreq.html As for digital gates, I couldn't recommend more the TTL and CMOS cookbooks by Don Lancaster: they're a goldmine of ideas. 2nd one is available for free at author's site. https://www.tinaja.com/ebooks/cmoscb.pdf https://www.tinaja.com/ebooks/cmoscb.pdf