[doe_eyes]

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.

[georgeburdell]

Yep, came to this realization awhile ago, about the superiority of digital in many cases, when I had an amplifier project with a dizzying number of requirements and a very large dynamic range and (log) linearity needed. Ended up using a few ranges of ADC’s, doing the required mathematical transform on a MCU, then outputting the required voltage with a DAC. The previous gen was some fairly complex circuit designed by a smart analog guy and still wasn’t nearly as performant

[lightedman]

"You're quite unlikely to find it in any competently-done commercial designs."

You'll find them in tons of commercial designs - your modern headlights (which I manufacture) and off-road lights use them in droves. Short-timed lighting like automatic UVC sterilization lighting and such also still relies heavily upon a 555 timer just to act as the on/off switch for the power driver pushing the LEDs.

[amluto]

Now I’m curious: what is the role of the 555 timer in a headlight?

I have a bit of a pet peeve about car lights (usually exterior lights that aren’t the headlights) that are visibly pulsed. They can be distracting. I think they should all be designed to operate either at silly frequencies that are genuinely undetectable by human eyes (30kHz?) or to genuinely operate at DC.

[theamk]

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]

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.

[dsv3099i]

I think it's more that the 555 is basically the heart of hysteretic controller in a box, but it doesn't have the other stuff you need.

https://en.wikipedia.org/wiki/Bang–bang_control

There's still plenty of analog control out there, it's just all hidden away as parts can integrate the sensor, controller and actuator, all in one magic IC. And it can definitely be lower power and cheaper, in volume. The main weakness is the NRE is higher than the typical MCU project so it's not really seen in low volume or hobby level stuff.

[buescher]

Even in jellybean analog, almost everything you can do with a 555 timer you can do with a quad comparator. And more. Over a bigger voltage range, too. It’s usually a design smell to see a 555 used for anything in a professional design, even from before the tiny mcu era.

It makes a nifty missing pulse detector, though.

[iwaztomack]

Its kind of interesting: the 555 is such _horrible_ timer. It can't do a 50% duty cycle without extra BOM parts, even more parts to make a real PWM out of it, and it has terrible temperature and voltage stability. But somehow it persists.

[MisterTea]

Bob Pease has a pretty scathing opinion: https://www.electronicdesign.com/technologies/analog/article...

“Hi, Jeff H., I have almost never used a 555. Maybe never? I use op-amps, LM324's, LM311's, LF356's. I use 74HC04's and 74C14's but not 555's. I've used ECL fast logic, and discrete transistors. But the 555 just does not do anything precise, or even semi-precise, that I need done. So that's one thing I can "share" - my favorite circuit to use a 555, is: a blank piece of paper. Never touch the things. Go ahead and print that. / rap”

[irunmyownemail]

There's still room for synchro and servo theory I learned in the Navy but I really like the digital world a lot, so flexible.

[vicnov]

Can you recommend books/courses that cover this new approach you’re talking about?