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!<p>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.<p>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.
We sell kits with plenty of 555 timers (including some listed here)<p>It’s a shame that Arduino has effectively truncated kids learning with a full MCU as the “building block” of their learning<p>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<p>About half the kids I see make the intellectual jump, half end up not coming back<p>I do wish kids were taught basic soldering, it would make the learning process a lot less worrisome<p>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
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.
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.<p>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.
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.
The awesome Ben Eater gives the clearest explanation I've seen of how the 555 timer works internally: <a href="https://www.youtube.com/watch?v=kRlSFm519Bo" rel="nofollow">https://www.youtube.com/watch?v=kRlSFm519Bo</a>
Shout out to Forest M Mims III, the OG 555 circuit guru.<a href="https://en.wikipedia.org/wiki/Forrest_Mims" rel="nofollow">https://en.wikipedia.org/wiki/Forrest_Mims</a>
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.
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.<p>As an example, here's a equalizer built around a 4049 quad inverter gate chip.<p><a href="http://www.runoffgroove.com/mreq.html" rel="nofollow">http://www.runoffgroove.com/mreq.html</a><p>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.<p><a href="https://www.tinaja.com/ebooks/cmoscb.pdf" rel="nofollow">https://www.tinaja.com/ebooks/cmoscb.pdf</a>
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.<p>More details if curious: <a href="https://www.reddit.com/r/amateurradio/comments/1eo9ki7/xiegy_g90_cw_keyer_skipping_dits_fixed_with_a_555/" rel="nofollow">https://www.reddit.com/r/amateurradio/comments/1eo9ki7/xiegy...</a>
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.)<p>1) <a href="https://www.talkingelectronics.com/projects/50%20-%20555%20Circuits/50%20-%20555%20Circuits.html" rel="nofollow">https://www.talkingelectronics.com/projects/50%20-%20555%20C...</a>
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.
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": <a href="https://youtu.be/PQOjkuJtBfM?si=Np2MSKgAp4ULwzcl" rel="nofollow">https://youtu.be/PQOjkuJtBfM?si=Np2MSKgAp4ULwzcl</a>
Clark Zapper… Hmm sure offers some interesting properties!<p>> This device is used tocure, treat and prevent any disease. It will cure anything.<p><a href="https://www.555-timer-circuits.com/clark-zapper.html" rel="nofollow">https://www.555-timer-circuits.com/clark-zapper.html</a>
Might be interested to check out this legendary book: <a href="https://en.m.wikipedia.org/wiki/The_Art_of_Electronics" rel="nofollow">https://en.m.wikipedia.org/wiki/The_Art_of_Electronics</a>
The internal diagram appears to be incorrect, <a href="https://www.555-timer-circuits.com/inside-the-555.html" rel="nofollow">https://www.555-timer-circuits.com/inside-the-555.html</a><p>The internal resistors should be connected to the upper comparator. Also, that diagram just seems confusing. Something like this makes more sense: <a href="https://www.theengineeringknowledge.com/wp-content/uploads/2020/09/Internal-diagram-of-a-555-integrated.jpg" rel="nofollow">https://www.theengineeringknowledge.com/wp-content/uploads/2...</a>
Well, you can also build microprocessors out of them:<p><a href="https://hackaday.io/project/182915-555enabled-microprocessor" rel="nofollow">https://hackaday.io/project/182915-555enabled-microprocessor</a>
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".
> VCC +4.5 to 15V<p>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?