"555 Timer is soooo versatile", really? - Page 1
Forum section: electronics / projects

author: dastructhm
author_rank: Contributor
timestamp: October 09, 2022, 01:18:36 am
content: People say its application is huge. Yeah. I know. Like its astable mode, bistable mode, etc, just to blink LED's. Okay, but...that's it?In real world, what do engineers use the 555 Timer for? in real products, I meant.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 09, 2022, 01:33:18 am
content: Has been discussed before:https://www.eevblog.com/forum/chat/where-have-you-actually-come-across-a-555-timer-in-the-wild/I forget when I last used one (in the intervening years). They're still one of the best for a random signal source or latch. It's rare that you need that, and can't simply grab a spare timer + pin on an MCU, or have some spare gates for an RC oscillator, or use something more purposeful like a switching regulator or what have you. And they're still cheaper than e.g. LT TimerBlox or whatever (though maybe not smaller -- depends which versions you're looking into, the improved ones of which may not be as cheap either!).Tim

author: Whales
author_rank: Super Contributor
timestamp: October 09, 2022, 01:36:37 am
content: Almost never. Assembly & inventory costs mostly outweigh chip costs, so you're better off using a micro rather than a 555 and associated parts.I use it for fun however. Recently I wanted an astable oscillator that had (fully) independently controllable low duration and high duration. None of the circuits I've found on the web do that. I didn't want to use a micro for age-spriritual reasons (going into a car from 1969). The parts I did use are definitely modern (CMOS) but they had predecessors in the 60's & 70's, so it felt a lot more fitting.EDIT: You could possibly skip the inverter in my schematic by instead using the discharge pin of the 555 and a pull-up resistor, but I already had an inverter spare in this design.

author: John B
author_rank: Frequent Contributor
timestamp: October 09, 2022, 01:43:05 am
content: My most recent use was a hardware based transmit enable pulse for an RS485 transceiver. It's for a RPi where a software solution wont work. Sure a microcontroller could replace it, but it wasn't worth the hassle.

author: dastructhm
author_rank: Contributor
timestamp: October 09, 2022, 02:04:33 am
content: Quote from: T3sl4co1l on October 09, 2022, 01:33:18 amsorry...oh, wait..."Warning: this topic has not been posted in for at least 120 days.Unless you're sure you want to reply, please consider starting a new topic."

author: John B
author_rank: Frequent Contributor
timestamp: October 09, 2022, 02:11:45 am
content: Oh yeah and part of the same project.... I made an over-power fault protection circuit in a linear constant current driver. An op-amp circuit provides a control voltage proportional to the power dissipated, then a 555 timer trips and turns off the output for a second. Basically a hiccup fault protection mode.

author: exmadscientist
author_rank: Frequent Contributor
timestamp: October 09, 2022, 02:20:41 am
content: I wanted to use one to blink the safety critical "output is hot" LED on one of our projects. The firmware people instead successfully shoved some horribly complicated microcontroller-CAN thing down everyone's throats. (Which is actually a fine approach most of the time!Except, in my opinion, for the one single LED the user looks at to determine if the thing is lethal right now.Thatone should be hardware, especially since the line I'd have driven it off of was already available.)(Also, if you ever have a safety-critical LED,do notblink it on-off. Blink it bright-dim. That way glancing at it can never show it as totally off.)

author: SiliconWizard
author_rank: Super Contributor
timestamp: October 09, 2022, 03:02:25 am
content: Thought I would never have to use them again, but, what do you know... I actually used a TLC556 for handling some specific kind of reset circuitry, implementing a chain of two monostables, in an existing design. While using a very low-cost MCU may have been slightly lower cost, it would have required some software and some programming at production time (or ordering pre-programmed parts, which is only worth it for pretty large quantities). So since the TLC556 was actually available, there you go!

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 09, 2022, 03:30:16 am
content: Quote from: dastructhm on October 09, 2022, 02:04:33 amI mean, it says warning, not error.Also, in case you didn't see it before, and also, now it's linked here.Quote from: John B on October 09, 2022, 02:11:45 amKinda like this but a longer time constant:https://www.seventransistorlabs.com/Images/555%20Boost.pdfWhich also shows that you can indeed use it as [part of] a switching supply. But it's rather a force-fit. Notice all the support components to make it an at least passable current-mode control.Tim

author: bdunham7
author_rank: Super Contributor
timestamp: October 09, 2022, 04:10:04 am
content: If you count the close variants, Mouser hasseveral millionunit in stock. Annual production is (or was recently) something like a billion per year. And that is 50 years after it came out. So yes it is versatile and I see it used in all sorts of odd places where either there is no microcontroller or for some reason they don't want to use it. Now as far as using it new designs, I suppose small low-production gizmos where someone familiar with 555 tricks doesn't want to bother programming something. Adjustable PWM for small motors and LEDs probably account for a few metric tons of these every year.

author: Deactivated-1
author_rank: Frequent Contributor
timestamp: October 09, 2022, 04:32:13 am
content: Quote from: dastructhm on October 09, 2022, 01:18:36 amI've seen it be used in 8 bit atari computers for an turn-on-reset circuit

author: DonKu
author_rank: Regular Contributor
timestamp: October 09, 2022, 04:33:20 am
content: My 555 powerbank keepalive:https://crcomp.net/mp3mod/My webpage needs an update because the mp3 player shown on it was replaced by:https://www.ebay.com/itm/304571755908.

author: AlcidePiR2
author_rank: Regular Contributor
timestamp: October 09, 2022, 05:27:55 am
content: MCU everywhere is the best chance for obsolescence of products. You fry the MCU, you can trash the product, as usually you cannot get the firmware.You fry a 555, just replace it by a new one and you are good again.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 09, 2022, 08:36:08 am
content: Quote from: AlcidePiR2 on October 09, 2022, 05:27:55 amParts do not just fry. Microcontrollers are extremely reliable.

author: EEVblog
author_rank: Unknown
timestamp: October 09, 2022, 08:44:48 am
content: A 555 pops up very often in my teardowns of all sorts of stuff.

author: Terry Bites
author_rank: Super Contributor
timestamp: October 09, 2022, 10:40:42 am
content: The only time I use them these days is as a simple comparator.They should have got rid of CV pin long ago and given a 50:50 output pin.A re-tirggerarble option would have been handy too.CV is/ was hardly ever used PWM is a micro thing now.Its a novelty. Thats it. Put 'em in the grinder with the 741s

author: RoGeorge
author_rank: Super Contributor
timestamp: October 09, 2022, 10:47:25 am
content: Quote from: dastructhm on October 09, 2022, 01:18:36 amYes. That, and AM radio.Schematic from:https://tubetime.us/index.php/2011/02/23/555-contest-entry/

author: Zero999
author_rank: Super Contributor
timestamp: October 09, 2022, 11:07:41 am
content: One thing to note is, the 555 is not a beginner friendly IC. Attention needs to be paid to layout and decoupling.I'm not a fan of the 555. There are some instances where it's the best IC for the job, but there are normally more suitable alternatives.Quote from: AlcidePiR2 on October 09, 2022, 05:27:55 amThat's the manufacture's fault. They could easily make the firmware publicly available, if they wanted to make it easy to repair.

author: jonovid
author_rank: Super Contributor
timestamp: October 09, 2022, 11:21:34 am
content: Quote from: RoGeorge on October 09, 2022, 10:47:25 ammy chance for most of my DIY projects as I am familiar with the venerable old 8 pin DIPAM radio ? a guitar fuzz pedal would be a better use of that level of distortion

author: mc172
author_rank: Frequent Contributor
timestamp: October 09, 2022, 11:23:11 am
content: I've not ever designed a 555 into a product but have used them to make very simple test rigs and the like. Very handy if you need to flick a switch a few hundred thousand times or whatever.

author: Ground_Loop
author_rank: Frequent Contributor
timestamp: October 09, 2022, 11:27:27 am
content: I recently salvaged a surface mount version out of a failed variable frequency drive (VFD). No clue what it was being used for.

author: mc172
author_rank: Frequent Contributor
timestamp: October 09, 2022, 11:29:52 am
content: Quote from: mc172 on October 09, 2022, 11:23:11 amHaving said that, there always seems to be a stash of them everywhere I've worked, the stash being more than anyone is ever going to get through in a lifetime. I've even got a tube of about 50 of the through-hole DIP variety knocking about at home. Some place I worked 10 years ago was throwing them away with a load of other crap so I grabbed them, probably after falsely convincing myself that they'd be really useful. I've used three from the tube in that many years, assuming it had 50 in it when I acquired it!

author: retiredfeline
author_rank: Frequent Contributor
timestamp: October 09, 2022, 12:03:24 pm
content: You have to evaluate that "so versatile" claim against the technology 50 years ago. Before '72 you wanted a circuit for one of the supported modes you needed a handful of discrete components. Then comes this 8 pin IC that simplifies design. Nowadays the required functionality can be folded into the MCU. Just a bit more firmware, no extra hardware. No MCUs in those days, remember.I haven't owned one or felt like using one for decades.

author: mc172
author_rank: Frequent Contributor
timestamp: October 09, 2022, 01:52:21 pm
content: Quote from: retiredfeline on October 09, 2022, 12:03:24 pmIt feels like there's no MCUs these days either what with this chipageddon nonsense still going on!

author: jbeng
author_rank: Regular Contributor
timestamp: October 09, 2022, 03:58:25 pm
content: Quote from: Zero999 on October 09, 2022, 11:07:41 amThat's rather interesting, because as an electronics beginner in the mid 1970's, the 555 was the first IC I ever used.I still use them, though now in SMD.Quote from: Zero999 on October 09, 2022, 11:07:41 amThat's a big problem as they see it though... the manufacturer usually doesn't want you to repair the broken product, they want you to buy a new one. If manufacturers made their products easily repairable, there would be little incentive for you to replace it and their profits would suffer. Make it diffcult/impossible to repair and replacement is about the only option.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 09, 2022, 04:34:03 pm
content: Well, sure, you could use it as a timer and it is versatile, but not very modern.

author: Electroplated
author_rank: Regular Contributor
timestamp: October 09, 2022, 07:07:09 pm
content: Used two 555's in a new linear PSU design a few weeks ago, one 555 is part of the cooling fan pwm control, the other 555 is used a simple push button toggle switch for the outputs.The 555 is my favorite IC and I have used one or another of its incarnations since it first became available, it even features in a rather basic scope I made back in 79, using a salvaged radar crt. A 555 fed with a constant current generated the linear saw-tooth for the sweep and another one provided flyback blanking. ( it still works albeit the tubes rather dim now )think I will using them for a long time seeing as I have 470 of them due a slight mishap on my ordering sheet years ago, was 500 but I have used a few since then--

author: Ranayna
author_rank: Super Contributor
timestamp: October 09, 2022, 08:26:46 pm
content: I tore down an LTO-4 Drive made by IBM some time ago.I was somewhat surprised to see not one, but two 555 chips on the main board.Considering what else is all on that board, the 555s seem very anachronistic.

author: JPortici
author_rank: Super Contributor
timestamp: October 09, 2022, 08:37:00 pm
content: Quote from: exmadscientist on October 09, 2022, 02:20:41 ambut then you have scores of users that complains that it's always on and think that dimming is a problem because they find it strangebut to stay on topic, i will use it in a future product to implement a hardware watchdog. In the event the MCU is stuck one part of the circuit need to be bypassed. This is going to be done via a relay that is controlled not from the MCU directly, but from a monostable, retriggerable multivibrator that will be implemented with 555Also the OP should take one of the many 555 cookbooks and see what you can do if you get creative

author: jonpaul
author_rank: Super Contributor
timestamp: October 09, 2022, 09:15:27 pm
content: in 1970s..1980svariable siren, bike hornADC DAC isolation power supply driverfrequency..period to analog converterSee Don Lancaster's IC timer cookbook, 1970sJon

author: dastructhm
author_rank: Contributor
timestamp: October 10, 2022, 01:00:18 am
content: Quote from: Electroplated on October 09, 2022, 07:07:09 pma toggle switch with a 555? I wanna learn its schematic.

author: Geoff-AU
author_rank: Frequent Contributor
timestamp: October 10, 2022, 11:27:09 am
content: I just bought some 555 for a project - they go up to 2.1MHz!I sure can't count that fast!

author: Berni
author_rank: Super Contributor
timestamp: October 10, 2022, 11:43:44 am
content: Yep i seen 555 timers in products. Things like turbo buttons on game controllers, beeping things, RS485 repeaters as TxEnable recovery, PWM signal generation etc...However most electronics products have gotten much more complex to a point where other chips can often do the job of a 555. Like as soon as there is a microcontroller in there it makes sense to let it do all the timing.The neat thing about a 555 timer is the versatility to be able to make it to so many different things depending on how you wire it up. Sure it takes a good deal of passives around it to actually make it run, but doing a lot of these tasks with discrete transistors or even opamps would take even more components.

author: Siwastaja
author_rank: Super Contributor
timestamp: October 10, 2022, 12:20:53 pm
content: Quote from: JPortici on October 09, 2022, 08:37:00 pmThis. If you have to go so far that on/off blinking is not indicative enough, then the classic solution is two lights that blink alternatively. This has the benefit of broken light being instantly obvious while the other one still provides indication.

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: October 10, 2022, 12:28:15 pm
content: I think it will be rare when using one in high-volume production is the 'right' choice (things change in low volume when time to design >>> cost of actual parts).That said, my students still love them and I suggest them a lot, lots more hands on than some 'digitalWrite()' funtion that goes on and off a lot.

author: Warhawk
author_rank: Frequent Contributor
timestamp: October 10, 2022, 12:58:09 pm
content: Quote from: dastructhm on October 09, 2022, 01:18:36 am555 timer still pop-ups frequently. I can confirm that you can find it even in new electric vehicles. There are many reasons why. 555 time comes from many sources, is cheap, does not require programming during production, functional safety and it often "does the job".

author: Electroplated
author_rank: Regular Contributor
timestamp: October 10, 2022, 09:36:51 pm
content: Quote from: dastructhm on October 10, 2022, 01:00:18 amThis is the toggle switch, taken from one of my project diagrams. The 'protect' connection disables the output so long as its held low, in this circuit its part of the over volt tracking and over heat protection section of the psu but could be used for other purposes.-

author: b_force
author_rank: Super Contributor
timestamp: October 10, 2022, 10:49:57 pm
content: Lately I have been going towards just logic gates (again!) instead.It just takes one inverting schmitt bugger to do already many things like PWM drivers, led drivers etc etcDo this with like a NAND or so and possibilities grow fast.A 555 is just a very jelly bean part with so many applications (even a buck, boost converter is no problem).These days there are just many alternatives that are very affordable.Still the majority of those more "specialized" still contain parts that can be found in e 555 as well.But to answer the question, no I very rarely use a 555 anymore these days.In the past it was kinda my goto for any kind of prototyping or DIY projects for many things.

author: JPortici
author_rank: Super Contributor
timestamp: October 11, 2022, 06:04:02 am
content: Many analog synthesizer use a 555 for the AD/ADSR/more more complex envelope generators (rene shmidtz, ray wilson and yves usson websites come to mind).However many implementation didn't include a very important element, the buffering of the 555 RC output before going into the other stages. The envelope time parameters affected each other.

author: james_s
author_rank: Super Contributor
timestamp: October 11, 2022, 07:14:19 am
content: Quote from: dastructhm on October 09, 2022, 01:18:36 amNow? Relatively little, they're a vintage part with far less use than they once had although they do still pop up now and then.In the past they were used all over. Both the Wells Gardner and Amplifone color vector monitors used in millions of Atari arcade games used a 555 in the high voltage supply for the CRT. Dozens of early arcade games used 555's to generate sound effects. Lots of 80s-90s toys used them to blink lights or make sound effects. They've been used in time delay relays, lamp flashers, sirens and alarms, motor speed controllers and countless other things.

author: james_s
author_rank: Super Contributor
timestamp: October 11, 2022, 07:21:23 am
content: Quote from: ELS122 on October 09, 2022, 04:32:13 amThat reminds me of another famous use, as a joystick or pot ADC, Pong was a notable use of them. I think some 8 bit computers did too.

author: james_s
author_rank: Super Contributor
timestamp: October 11, 2022, 07:25:06 am
content: Quote from: Siwastaja on October 09, 2022, 08:36:08 amI've had parts just fry, sometimes there was some unknown underlying cause, other times I accidentally fried something by shorting it or some external fault. I've also had microcontrollers fail, a bad voltage regulator can kill them, and I've had a cascade failure where a mosfet blew and the HV tracked back and blew up the micro. Lighting strikes blow up loads of stuff in areas that get a lot of those. Failed programmable parts are a serious problem that hinders repair efforts.

author: james_s
author_rank: Super Contributor
timestamp: October 11, 2022, 07:31:02 am
content: Quote from: jbeng on October 09, 2022, 03:58:25 pmIt doesn't matter at all. The people who are going to try to repair some consumer device, at least one that costs a few hundred dollars or less even if it is made such that it is very repairable are statistically insignificant. I can't count the number of things I've been given that had absolutely trivial faults yet the owners replaced them rather than try to repair it or have somebody repair it. There is absolutely no reason for a company to deliberately make something difficult to repair because 99.99% of customers are just going to throw it away when it breaks anyway.

author: jonovid
author_rank: Super Contributor
timestamp: October 11, 2022, 07:33:09 am
content: just one of many uses

author: JPortici
author_rank: Super Contributor
timestamp: October 11, 2022, 08:32:21 am
content: Quote from: Siwastaja on October 09, 2022, 08:36:08 amIdiot user does idiot things such as applying overvoltage (willingly or by mistake). Unless it's an old design that used microprocessors with external memory so you can find someone that has read the firmware, the only one that can repair is the manufacturer

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: October 12, 2022, 12:22:16 am
content: 2 or 3 years ago, I had to come up fast with a test aid for our service technicians which is used to determine- whether the 1PPS-pulse from a GPS receiver is strong enough at the end of a cable run- whether it appears regularely and without interruption= 1 comparator with a 'buffered' 10-turnpot to adjust the level threshold precisely, NE555 as missing pulse detector (retriggerable monoflop), remaining half of the double compatator as a latching indicator. Done.

author: amymcneil
author_rank: Contributor
timestamp: October 12, 2022, 01:36:02 am
content: I'm using a 7555 in a widget I'm building for a friend of mine. I need a ~200 millisecond pulse with a 1Hz repetition. Also needs to run on microamps. And be able to drive a mosfet directly. The 7555 fills the bill perfectly for this. Cheap, available from multiple manufacturers, no firmware (there's no micro in the widget).In the past I've used them for timers, threshold detector/latches, one shots and as an AC mains zero crossing detector. Yeah, it's ancient, but there's a lot you can do with the bits inside of one.Nice Tek 555. Mine isn't as pretty - still waiting for me to work on restoration.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: October 12, 2022, 05:11:49 pm
content: Quote from: amymcneil on October 12, 2022, 01:36:02 amThat's not mine but I have a 547 and a 567. Even I have to draw the line at a 555. Unless there's a free one in Montreal... Just too big and onerous for me otherwise.Kinda envious though.

author: Electroplated
author_rank: Regular Contributor
timestamp: October 12, 2022, 07:05:21 pm
content: Ha, found another of my 555's in a led garden light, forgot about it, not surprising as it was over five years ago when I build the circuit, its just a crude and rude drop down switching reg that drops the 12v to 5v for the led. Dam LED gave up the ghost a few days ago, Once the led was swapped out, the light sprung back to life, not very exciting I know, but still very much 555 related !-

author: james_s
author_rank: Super Contributor
timestamp: October 12, 2022, 08:28:35 pm
content: Quote from: Electroplated on October 12, 2022, 07:05:21 pmI wonder if it's actually any more efficient than just using a resistor in that application. Or 2-3 LEDs in series with a resistor. Most garden lights have a switching converter because they're stepping the voltage UP to run a white LED from a single AA cell.

author: bsfeechannel
author_rank: Super Contributor
timestamp: October 13, 2022, 02:01:04 am
content: I recently acquired a used GW Instek analog scope. The calibrator was a little off in frequency, so I resorted to its schematic and what, do you suppose, provides the 1KHz calibrated signal? You guessed it: a 555.And here it is in all its glory!Now the calibrator is calibrated to spec.

author: Electroplated
author_rank: Regular Contributor
timestamp: October 13, 2022, 06:20:38 pm
content: Quote from: james_s on October 12, 2022, 08:28:35 pmIts one of those colour changing led globes, the LEDS need 4.5v each to work correctly. There are many ways to derive 5v from 12v but I went with the 555 as it was on hand at the time. At the other end of the scale we have a lampost type light that I modded so the 12v supply was stepped up to power three flame effect neon candle type bulbs, it also used a 555 and a coil to boost the voltage.Its works but not very efficient so I designed a similar lighting effect with orange Osram SMD leds and CC driver, far brighter and more efficient.All this garden lighting was intended as a simple project but over time it got way out of hand and now I just have lights or ornaments chucked at me with the instructions 'to do something with it'.