Interview Question (your Sunday ruined part 2)

I've created my own library for Claris Works, which I use for all my circuit diagrams. I prefer wiggly resistors and no four-way junctions, but I take a mix & match approach to the various standards.

My resistors are the old British standard. My electrolytic capacitors are the pre-war German standerd (with my own home-made symbol for non-polar types). The two-rectangles British Standard is counter-intuitive nonsense and a nightmare to draw and shade in. Resistor marking is 4k7 but, below 1k, I put in the omega symbol to avoid confusion. Capacitor marking is similar: 2u2f, 1n5f etc. Crossovers are indicated by a gapped line; four-way junctions are

The one symbol I have never been sure about is a battery. Apparently there were two different standards, one where the longer line represented the positive and the other where it represented the negative. I always indicate the polarity and the voltage alongside the symbol. e.g.

They should use that for interviews at Siemens corporation.

What's the point of that?

Wasn't the zigzag used everywhere for 100 years?

A rectangle could be anything.

What's the point of that?

Wasn't the zigzag used everywhere for 100 years?

A rectangle could be anything.

Do French engineers use the same convention on their schematics?

I can't recall ever seeing a French schematic, actually.

But if it's priced in cents, the cents symbol goes last.

We follow SI rules in engineering, but in everyday life the quirky old stuff is sort of fun. We measure distances in blocks or football fields and fluid volume in olympic-size swimming pools, or sometimes acre-feet.

I don't know, but the comma is in everyday use as a decimal point.

I can - and it was dreadful ! It was of a laboratory R.F. signal generator and they had put the earthing point in the centre with the various sections of the circuit radiating like the spokes of a wheel around it. The HT line ran around the outside.

I don't think they do it like that nowadays.

But you then have to read the identifier before you know what the component is. The whole point of a symbol is that it is symbolic, so you can scan over a circuit and see the general outlay without having to read what every component is.

Yep. The pad is even marked A, the other K; too small to be seen in the static image. I have several other footprints for LEDs in different sizes and orientations.

I never thought anything of it, and liked it, until I first went to the USA and someone asked what my strange resistor values meant. Since things are becoming more global I try to avoid it now.

I don't like rectangles for resistors, that looks awful, and don't get me started on IEC logic symbols.

...or even measurement?

I once heard the BBC's ' Environment Analyst' describe air pressure in Degrees Centigrade.

You use your states as units too. I wonder how many Americans actually know how big "half the size of Oregon" is. :)

Liz Tuddenham schrieb:

That's just sort of "used to" ...

Not a schematic, but many years (ok, decades) ago I was working in France and was surprised when a programmer interpreted a comma in my code as a decimal point. It was Forth code, and the comma in fact represented a double (32 bit) number. Lots of confusion. Kesker-say, nespar, un petit d'un petit s'étonne aux Halles and so on.

Ah Mots d'Heures: Gousses, Rames. I forget when I first came across that.

There are people, even gigabuck organizations, who are obsessed with single-point grounding.

That gets crazy fast.

Decoupling capacitors such as 0.1uF everywhere can also be an obsession. Remove them from many (not all) circuits with no change in performance.

Bigger than a bread box, for sure. ;)

Cheers

Phil Hobbs

A pizza is a unit of area, but they tend to not be constants.