When I was in college I was not in an engineering program but I was self-learning electronics. I was trying to learn to use a 555 timer to do something and couldn't get it to work.

So I went to the office hours of a random EE professor thinking they would help me out. Instead I got scolded about how 555 timers are not real engineering and that I shouldn't waste his time.

I never used a 555 timer ever since.

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jacquesm 6 hours ago | parent | next [-]

What a spectacular failure of education.

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rcxdude 5 hours ago | parent [-]

A little bit (scolding a beginner in this way is never acceptable), but I do feel like the 555 is really overrepresented in electronics learning materials. It's a quirky little chip, so learning about it doesn't really teach you much (most of the time it's just 'hook it up like so and it does this!', not 'here's how comparators and oscillators actually work'), and it's also now almost never the best or even a good solution for any of the problems it solves.

	▲	jacquesm 4 hours ago \| parent \| next [-]
		That's true but because it is a quirky useful little chip it is for many people their first exposure to integrated circuits that are a bit more 'analog' than gates and micro controllers. Opamps are the other gateway drug I guess. It's excellent teaching material for that reason alone, you do learn about it if you try to understand what makes it tick (there are plenty of articles about it, including blown up versions). I agree it is not the best solution for most applications but I'm happy to admit that I've actually used it in production designs (more than once, actually) where it made good sense to have a component that didn't have to be programmed. If you have a soft component on a board and a spare io line then you are usually better off doing it in some different way. I've seen some interesting applications of 555s that would have taken a lot more hardware otherwise, one of which was an oven controller with used a thermistor to directly affect the PWM output of a 555.
	▲	Tade0 an hour ago \| parent \| prev [-]
		It's true. They're not useful for anything not hooked up to mains. I was meaning to add footstep-activated lights to my stairs using vibration sensors and 555 timers, but then I learned that if I tried to operate them from a battery, the 555 would drain it in hours, while a much more sophisticated ESP32-c3, would last a month in sleep mode on two coin batteries or one li-ion in the same form factor all while being part of a development board that greatly increases idle current.

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foxglacier 6 hours ago | parent | prev | next [-]

I used to salvage components from electronic stuff and was always looking out for 555s but never found any, in a whole range of vintages from 1970's to 2000's. I ended up with the same conclusion - it seemed to be a hobbyist's chip that real consumer products didn't use and felt amateurish for some reason I didn't understand.

	▲	leoedin 4 hours ago \| parent \| next [-]
		The big problem I ran into playing around with 555s was that capacitors are very rarely the capacitance they claim. Unless you're speccing an expensive capacitor, you'll find your time constant varies quite a bit across devices and temperature. That's fine for some use cases, but completely a deal breaker for others.
	▲	tralarpa 5 hours ago \| parent \| prev [-]
		That's funny because I have two objects on my desk for which I know that they use 555s. One is a no-name joystick with "autofire" function from the late 1980's. The other is a mass produced motor controller from the 2000's where the 555 generates the PWM signal for a FET.

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teaearlgraycold 5 hours ago | parent | prev | next [-]

How hilariously transparent that he didn’t know how to use a 555 and didn’t want to admit it.

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Joel_Mckay 5 hours ago | parent | prev [-]

That is a terrible learning environment. Our profs always leave a box outside the laboratory with free expired textbooks, partial part lots, and damaged/old test equipment.

Some people get into Science, Software, and Electronics for the wrong reasons.. And end up miserable teaching after failing in the private sector.

A few 555 can teach people a lot, and burning out parts is part of the learning process. Most fold the DIP legs under like a "dead bug", as that is the tradition to prevent its accidental re-use.

In terms of component cost, ATTINY or PIC10 mcu have internal RC oscillators with configurable PWM pin hardware. Thus a single component is usually better than the accumulated precision error in discreet parts around a 555.

I usually recommend an RC car/truck build, https://eater.net/6502 , and or an LDOmotors Voron kit. Getting your Ham Radio technician license will also introduce you to an intuitive understanding of EE component model limits.

This covers a lot about discreet analog circuits, and I recommend trying to figure out how every circuit works on your own:

https://archive.org/details/encyclopediaofelectroniccircuits...

Simulators are not perfect, but they are a lot cheaper when starting out. =3

Tutorials:

https://www.youtube.com/@FesZElectronics/videos

Tools:

https://www.analog.com/en/resources/design-tools-and-calcula...

https://web.archive.org/web/20200218212700/http://spectrum-s...

This requires a GPU on Windows, but is a more advanced newer Spice simulator:

https://www.qorvo.com/design-hub/design-tools/interactive/qs...