[hilbert42]

Ah how things have changed. When I was learning electronics we mainly dealt with radio and TV circuits and just about the first lesson one learned was to keep leads short (reduce unwanted inductance) and use decoupling capacitors everywhere.

I recall some years later a young graduate engineer coming into my office with a rather involved circuit consisting of 30/40 TTL ICs and complaining that he'd double checked the circuit and it still didn't work. I took one look at his device then went to the draws of capacitors and handed him a handful of 0.1uF ceramic caps and told him to put them between the ICs' PS rail pins to ground which he did and to his amazement the circuit worked immediately.

He stood in amazement that I should have such insight so as to fix the problem at first glance.

How such critical knowledge can get lost in university training these days just amazes me.

[lefra]

My university made us use really crappy power supplies and dev boards. Nothing worked unless you first put a large bulk capacitor on the power supply's output, and small capacitors close to the components.

Also I got bitten by parasitics in capacitors very early in my career: capacitors of different face value will resonate with each other to effectively kill the decoupling network at a specific frequency (resulting, for me, in an amplifier with a nice hole in its frequency response).

[hilbert42]

Incidentally, in my post below on the MIT RadLab series I mention Vol 23. On p183 parasitic oscillation is mentioned. Also, I recall when working in the now defunct RCA prototype lab, one of the main cure-alls for parasitic oscillations was to place a ferrite bead on a transistor lead (between it and the PWA). It often worked wonders.

[hilbert42]

Excellent training, especially the parasitic bit. Trouble is somehow many aren't taught that stuff nowadays.

[baq]

Sounds like an opportunity to build a shenzhen i/o prequel

[madaxe_again]

I feel it’s a function of abstraction.

You learned when analogue circuitry was the norm. I learned when digital circuitry was simple enough that you could readily take something apart and understand it.

Now, EE courses often start with cad, simulations, digital electronics, and you end up with people building ziggurats atop an ocean of incomprehension.

It’s exactly the same thing with software.

I don’t scorn people for this, rather I see myself as fortunate for having learned in a time when the more fundamental knowledge was still worth learning - and that’s the rub - for a vast majority, it simply isn’t worth the time or energy to explore the full stack, when there’s so much to learn atop it.

[hilbert42]

"You learned when analogue circuitry was the norm. I learned when digital circuitry..."

What's not taught properly these days is that ALL electronics is analog at the physical/circuit level.

For you digital types that's OSI Model Layer 1 — Physical layer (look it up on Wiki). Nothing in electronics works unless that's working properly—ICs, tunnel diodes, transistors, inductors, resistors, capacitors, cables and antennas are all analog devices at that level. That includes the heart of the most advanced digital ICs. For example, the upper clock speeds in processors are limited by transit times/electron mobility, inter-electrode and stray capacitances, unwanted inductance, etc.—all of which are analog effects and they must be accounted for.

Like it or not, the physical analog world is alive and well! The Noughts & Ones Brigade unfortunately seems to have forgotten that fact.

[vintermann]

> you end up with people building ziggurats atop an ocean of incomprehension.

Everyone does. There's probably a layer below for everyone but the most theoretical physicists. I don't know where the leaks in electronics engineering's abstractions are, but I'm pretty sure they exist.

[madaxe_again]

This is why I went on to study physics - I never was someone who could stop asking “why?”

All it does is provide yet more profound questions.

[hilbert42]

"…I never was someone who could stop asking “why?”"

When a kid of about four I found a pair of WWII headphones and took them to my father who pulled out the iron diaphragm and showed me magnetism at work—somehow some magical force was pulling the diaphragm back into the headphone with seemingly nothing in between. Absolutely fascinated, I wanted to know what this invisible 'magic' was. Many decades later every time I look at my fridge magnets I still ask the same question and I don't believe I'm much closer to the truth!

Sure, there are the simple answers everyone's taught, then there's QFT but even that doesn't tell me exactly what's going on. And why does alpha have the value it does, and why exactly does c = 1/(μ0ε0)^1/2? Not knowing and not being able to figure these questions out is, at times, infuriating.

For me, solace of sorts can be found in engineering—I can build an electronic circuit and end up with a tangible working device. On the way I'll curse my electrons for making so much noise that they sound like ball bearings rattling around in an empty oil drum but I'll eventually calm down and apply Johnson–Nyquist to shut them up (well, a little bit anyway).

[madaxe_again]

Yes, exactly those questions, and others of the family. Things we can describe yet cannot yet explain - and “yet” is doing some heavy lifting there. Perhaps some things cannot be explained from our reference frame.

I got sucked into the infinite perspective vortex from the cosmology angle - a grandmother with a vast collection of pulp sci fi and clear skies over her canal boat. And yes, magnets, what is this devilry and why will nobody tell me how it works?

Upon discovering said imponderables I moved to the woods instead - building infrastructure of all varieties from the ground up, playing with hydropower, that sort of thing - and of course EE gets jammed in all over the place, and when I can get away with something simple and analogue, I do.

I build things because the alternative is spending tracts of time staring into the abyssal fact that explanation is always ultimately internal to the system being explained.

[sdenton4]

Well... https://xkcd.com/435/

[michaelt]

> How such critical knowledge can get lost in university training these days just amazes me.

It will probably have been taught.... but very briefly. Before going go back to analysing circuit schematics, where connections between components don't show resistance or inductance, and the capacitance of two parallel capacitors sums.

[st_goliath]

This is why lab exercises are important. I remember first building some actual TTL circuits on bread board, I learned very quickly that this whole digital stuff is a lot uglier and messier than on paper or in the simulator.

With sharp rise times, synced up to a common clock, even after soldering in a whole bunch of capacitors, you can still stick a probe pretty much anywhere and see switching spikes all over the place, from power rails to completely unrelated signals that are supposed to be stable. Using actual TTL, there was another funny lesson what this weird "fanout" value in the datasheet meant.

A similar lesson I learned that way (and a very memorable one :-)) was about flyback diodes.

[jacquesm]

Ah, but that may well be because of your scope probe's leads! The sharper the edge the more likely that will happen. That's what those shitty little springs are for that come with your scope probe: you disconnect the ground wire and put that spring on the naked scope probe pin around the ground collar. Then where you want to measure you use the pin to go to the signal and the little spring to reach the nearest ground. Presto: clean signal (or at least, much cleaner). Also, make sure to tune your probe (that's what the little plastic screwdriver with metal tip is for, there is a small trimmer in the probe you can reach through a hole and that is critical at high frequencies) and avoid probes with switchable 1/10 like the plague, over time the switches go lame and then you'll be tracking all kinds of weird gremlins.

[ben_w]

This is just reminding me of the time I played with an oscilloscope, touched the probe against my finger and found my body was antenna picking up mains frequency.

[derefr]

> or in the simulator

Inadequate simulator, then, no?

(I imagine analogue RF board-level simulation is a lot more expensive than digital-logic board-level simulation. Might have been impractical way back when, such that we only used to have the digital-logic kind. But we certainly have both kinds today.)

[ceejayoz]

I've struggled to find a proper introductory guide to stuff like this. Moving from pre-made Adafruit boards to my own PCBs was very tough to navigate; every guide I came across assumed you knew all sorts of stuff that the EEs writing them probably committed to deep memory decades earlier.

[dgroshev]

I found Phil's lab content [1] [2] indispensable for just this. Phil is a great communicator and gives in-depth explanations, so I didn't just watch most of his youtube, but also bought his mixed signals course and was very happy with it.

Phil also recommends this lecture in one of his videos [3], which is still one of my all time favourite lectures ever.

[1] https://www.youtube.com/@PhilsLab

[2] https://www.phils-lab.net/

[3] https://www.youtube.com/watch?v=QG0Apol-oj0

[jacquesm]

Fantastic stuff, esp. #3 which I had not seen before. Thank you.

[InUrNetz]

I have an MSEE from a top university (from 20 years ago), this topic unfortunately is not really taught. The theory and analysis is taught, but the practical implications were not. I connected the dots in my first job out of school where some very talented gray beards taught me how the real world works. Which brings me to my point that EE really is a trade. It takes schooling at the beginning and in most cases a degree or two, but there is critical knowledge that you learn in the real world after school; and there are levels analogous to apprentice, journey man, and master.

[Lerc]

I can see how that happens when people come at things from a conceptual digital side first.

It probably doesn't help when you have a circuit diagram that while topologically correct doesn't show the relative positioning between components. The first time I saw all the decoupling caps rendered in a single chain on the side of the diagram I was mightily confused. It seemed like utter nonsense until I realised where they actually went.

[hilbert42]

"The first time I saw all the decoupling caps rendered in a single chain on the side of the diagram I was mightily confused…"

If you've read my other comments here you'll realize I'm concerned that these days EE training doesn't place a strong enough emphasis on shielding, ground loops, decoupling and such that it ought to. For any electrical/electronic engineer these are critical concepts.

By way of stressing that I'd like to take a sojourn into history and refer you to probably the greatest set of electronic engineering books ever produced: the MIT Radiation Laboratory Series — a massive 28 volume set written nearly 80 years ago to document electronics and microwave/radar research done during WWII.

Anyone seriously interested in electronics should be aware of this series. Yes, it's dated, heavily weighted towards vacuum tube technology (although klystrons and magnetrons are still current), and it lacks modern semiconductor tech, however this truly remarkable set contains a huge amount of information that's still very relevant today. Moreover, whilst it covers the topics in depth it does so at a level that can be easily understood by undergraduates (explanations are more general than today's very specialized textbooks).

https://en.wikipedia.org/wiki/MIT_Radiation_Laboratory_Serie...

Here you'll find links to the Internet Archive where the volumes can be downloaded. Specifically, I would refer you to Volume 23 - Microwave Receivers, — Chapter 6 Intermediate Frequency Amplifiers p155. Now turn to p182 and read 6-10 Practical Considerations.

Here's the PDF of V23:https://archive.org/download/mit-rad-lab-series-version-3/23...

This section on decoupling, shielding etc. is just as applicable to today's high speed digital circuits as it was back in WWII. Sure it needs updating but the fundamentals of screening and decoupling have not changed. What's important here is that these physical (analog) effects are set by the fundamental laws of physics, and circuits that do not take them into account will fail to work correctly.

[hulitu]

> It seemed like utter nonsense

This is utter nonsense. Just ask the layouter where they will be placed. (at the output of the voltage regulator or where he will find empty space on the board, completely missing their function). Where your schematics is bad, the layout will be also bad.

[amelius]

https://xkcd.com/1053/