I got a teaching question and I need your opinion and experience.
The first thing that shocked me a few weeks ago was that I couldn’t read circuit schematics anymore. The way I learned to draw and understand circuits is like this (bottom):
The circuit is closed, because the first thing I usually teach in electronics is checking which materials are conductors and we learn: „An electric current only flows when the circuit is closed.“
When I saw the circuits with „Ground“ and then „Speaker Out“ I was stunned, because it was hard to understand for me. Including: Where does the other end of the speaker go? („Connect everything to ground“)
The ground circuit is easier to understand, if you are using a breadboard. (We don’t have them in school yet, but I think it’s about time to order some)
What way of drawing and understanding diagramms is it you would recommend for learning electronics, what was the way you learned it or teach it in school?
Another problem: We talk about electric charge and the atomic modell and the only parts that can „move“ (really slow, but I keep this for higher classes) are the free electrons with a negative charge. So the correct way a charge moves is to the positive end of a circuit. Whereas I’m thinking the Ground implies the End of a circuit. At least for me, and now I have to explain to my pupils that there’s a „electric way“ (charge goes from + to -) and the right way (charge goes from - to +).
I think the first question is if your main focus is to teach people how the “things” work, or how to deal with all the more or less obscure conventions the industry has developed over the years while doing so.
I’d concentrate on the “things” first. You just have to roll with some conventions (yes, current is “backwards” but that’s because they figured out that current was a thing that existed independently of frogs before they found the electron) while many other things might just be extra confusing if you introduce them too early.
E.g. with this circuit you could do something like:
Using closed schematics, wire up the circuit with just a battery, a resistor and a LED. Show that the LED needs to be the right way. Explain that the light comes from electrons going through the LED material being forced to change energy levels, and that extra energy is dissipated as photons, i.e. light.
Add the potentiometer, and show how you can vary the LED intensity by varying the current (amount of electrons).
Add a bit larger capacitor, and show how the LED only blinks once; once the capacitor has charged up, no current goes through the circuit.
Discharge the capacitor! and add the transistor, to make things blink.
Change to a smaller capacitor, hook up the speaker, and make noise!
Discuss symbols and simplified diagrams.
(fwiw, I’m no fan of “ground” as a concept when looking at individual circuits, partially because it’s too easy to conflate with “earth” and partially because voltages are always relative, and pretending they’re not isn’t helpful.)
EDIT: Misplaced part of the last aside; meant to say that I prefer 0 V over GND etc, since that’s what it is – an agreement on where the zero is in a given circuit, and thus what the other voltages are relative to that one.
I thought about the way to help pupils understand this circuit and any other circuit as well and it makes sense to go step by step and than analyze what every component is doing. Thank you.
Earth / Ground: It becomes even more confusing when you translate it into german because you can use the same name: Erde. I remember a class at university about electronics and our Professor was talking about “Erdung” the whole time, but he didn’t mean Earth, he meant Ground, but everybody was afraid to ask.
It depends on context, but “earth” often imply mains earth (which is literally connected to the physical ground) which may or may not be the same as circuit ground. And yeah, many languages use the same word for both.
I loved teaching B.E.A.M. robotics ; simple circuits, cute robots made of junk, another way to torture cmos chips and make em dance!
A few bits, “dead bug” style build and an hour or so later you’ve a new metal family friend shuffling across your desk (looking cute).
Fun times. Expect a revival
On language, I would use Earth to refer to the domestic mains earth connection (and earthed as an adjective), but nowadays I tend to defer to common practice when speaking of electronics. America has far more native English speakers on the internet than any other nation so many articles on the internet use American terminology. In short, I usually call it Ground in contexts we’re most likely to encounter on this forum.
“COM” is short for common, for meters with multiple ways to connect the leads, and while it’s usually the same as 0 V on most modern multimeters, that’s not necessarily the case on older devices.
Here’s one from the late 40s with a COM.+ terminal that’s used with either NEG or the two 2,500 V (!) terminals:
