"555 Timer is soooo versatile", really?

[dastructhm]

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.

[T3sl4co1l]

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

[Whales]

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.

[John B]

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.

[dastructhm]

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

sorry...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."
 

[John B]

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.

[exmadscientist]

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. That one 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 not blink it on-off. Blink it bright-dim. That way glancing at it can never show it as totally off.)

[SiliconWizard]

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!

[T3sl4co1l]

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

sorry...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."
 

I mean, it says warning, not error.

Also, in case you didn't see it before, and also, now it's linked here.

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.

Kinda like this but a longer time constant:
https://www.seventransistorlabs.com/Images/555%20Boost.pdf
Which 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

[bdunham7]

If you count the close variants, Mouser has several million unit 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. 

[Deactivated-1]

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.

I've seen it be used in 8 bit atari computers for an turn-on-reset circuit

[DonKu]

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 .

[AlcidePiR2]

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.

[Siwastaja]

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.

Parts do not just fry. Microcontrollers are extremely reliable.

[EEVblog]

A 555 pops up very often in my teardowns of all sorts of stuff.

[Terry Bites]

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

[RoGeorge]

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?

Yes.  That, and AM radio. 


Schematic from:  https://tubetime.us/index.php/2011/02/23/555-contest-entry/

[Zero999]

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.

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.

That's the manufacture's fault. They could easily make the firmware publicly available, if they wanted to make it easy to repair.

[jonovid]

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?

Yes.  That, and AM radio. 


Schematic from:  https://tubetime.us/index.php/2011/02/23/555-contest-entry/

my chance for most of my DIY projects as I am familiar with the venerable old 8 pin DIP
AM radio ? a guitar fuzz pedal would be a better use of that level of distortion

[mc172]

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.

[Ground_Loop]

I recently salvaged a surface mount version out of a failed variable frequency drive (VFD). No clue what it was being used for.

[mc172]

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.

Having 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!

[retiredfeline]

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.

[mc172]

No MCUs in those days, remember.

It feels like there's no MCUs these days either what with this chipageddon nonsense still going on!

[jbeng]

One thing to note is, the 555 is not a beginner friendly IC. Attention needs to be paid to layout and decoupling.

That'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.

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.

That's the manufacture's fault. They could easily make the firmware publicly available, if they wanted to make it easy to repair.

That'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.