Electronics oddities we still have to live with

[EPAIII]

Neither system is more logical. They are just different. Metric is easier to use.

More accurate? That may have a practical explanation. Designs and drawings using inches commonly use three decimal places or, in other words, thousandths of an inch. Designs and drawings using mm commonly use two decimal places or hundredths of a mm.

A hundredth of a mm translates to 0.000393... inches which is about 2/5ths of a thousandth of an inch.

So using the most common precision that is in common use for each of the two systems of measure, the metric design/drawing will be expressing the dimensions with about 2.5 times the accuracy of the one using inches.

Or at least apparently so at first examination. Yes, the tolerances are always a part of a mechanical design/drawing. And they should ALWAYS be expressed in any drawing. But metric does encourage/suggest the use of greater accuracy in the design process. Drawings of electronic parts where the tolerance is not expressed, 1.23mm is a more precise dimension than 0.048" because in each case a +/- one count in the last digit is assumed. And 0.01mm is less than 0.001" = 0.0254mm.

While this is not the way drawings using each system should be looked at, it is the way that some, dare I say many will look at them.

My two biggest frustrations are:
1) People who claim metric for dimensions is more logical; and

Metric is more logical, for the simple reason that every scale is related by powers of ten, whereas we have 12 inches to a foot, 3 feet to a yard, 1760 yards to a mile, etc.  However, there is no advantage in using metric for PCB design because that uses decimal inches (eg 1.27 inches).  No feet and yards there.

2) People who thing metric is more accurate.

Really? I've never heard of that before. Does anyone really think that?  I wonder if they mean more precise rather than more accurate, but of course that is nonsense, too. You can dial in any level of precision you want with either system.

[watchmaker]

I agree.  It is an ease f use thing, not accuracy or precision.  Most people who use imperial do use fractions and not decimals.  I personally am not facile with converting fractions to decimals like a real machinist although I can convert imperial fractions to metric fairly easily in my head.

But why bother, that is what digital measurement tools are for (thank you EEs)

FWIW, US watch factories were using metric at least for 100 years.  Interestingly, the panel mounting screws on WWII aircraft clocks were spec'd in imperial.  One advantage of metric is that for small parts fewer digits are required on the drawings making them easier to interpret.

[Zero999]

My two biggest frustrations are:
1) People who claim metric for dimensions is more logical; and

Metric is more logical, for the simple reason that every scale is related by powers of ten, whereas we have 12 inches to a foot, 3 feet to a yard, 1760 yards to a mile, etc.  However, there is no advantage in using metric for PCB design because that uses decimal inches (eg 1.27 inches).  No feet and yards there.

I'm comfortable with both metric and imperial. It doesn't bother me and I can remember the most common conversions.

Here's another one, regarding schematics:
What Euro-genius decided it was a good idea to use blank rectangles for resistors, instead of a proper (zigzag) resistor symbol?

(Attachment Link)

I prefer the rectangles. I'm terrible at drawing, so my resistors and inductors tend to look similar. It's much easier to just draw a box. I believe the square form comes from carbon composion resistors and the zig-zag from wire wound, but I could be wrong.

The same is true for logic gates. I can understand why some find a diferent shape for each gate is helpful, but a box with a symbol is much easier to draw.

[TimFox]

My two biggest frustrations are:
1) People who claim metric for dimensions is more logical; and

Metric is more logical, for the simple reason that every scale is related by powers of ten, whereas we have 12 inches to a foot, 3 feet to a yard, 1760 yards to a mile, etc.  However, there is no advantage in using metric for PCB design because that uses decimal inches (eg 1.27 inches).  No feet and yards there.

I'm comfortable with both metric and imperial. It doesn't bother me and I can remember the most common conversions.

Here's another one, regarding schematics:
What Euro-genius decided it was a good idea to use blank rectangles for resistors, instead of a proper (zigzag) resistor symbol?

(Attachment Link)

I prefer the rectangles. I'm terrible at drawing, so my resistors and inductors tend to look similar. It's much easier to just draw a box. I believe the square form comes from carbon composion resistors and the zig-zag from wire wound, but I could be wrong.

The same is true for logic gates. I can understand why some find a diferent shape for each gate is helpful, but a box with a symbol is much easier to draw.

Before schematic capture software, I had a set of inexpensive plastic drawing templates with good patterns for resistors, capacitors with straight and/or curved plates, inductors, transformers with cores, normal active devices, the usual logic gates, etc.  My usual one was small enough to fit in a shirt pocket.
For mechanical drawing, I had other ones with hexagons, circles, ellipses, and some mechanical fasteners.
I keep the templates in a desk drawer, next to my drafting triangles, for emergencies.

[tggzzz]

Before schematic capture software, I had a set of inexpensive plastic drawing templates with good patterns for ... the usual logic gates, etc.

I still have mine

I also have some Rotring drafting pens, required for a university course and never used thereafter. I wonder if I can flog them on fleabay

[TimFox]

Before schematic capture software, I had a set of inexpensive plastic drawing templates with good patterns for ... the usual logic gates, etc.

I still have mine

I also have some Rotring drafting pens, required for a university course and never used thereafter. I wonder if I can flog them on fleabay

With the US-made templates, I drew on Clearprint drafting vellum with 0.1 inch grid (still available).
In grad school, I took lecture notes with a "00" Koh-I-Noor Rapidograph drafting pen, especially in General Relativity with all the sub- and super-scripts.
Templates are still readily available:  https://www.draftingsuppliesdew.com/supplies/drafting-templates-and-drawing-templates?srsltid=AfmBOooIWZ6AR7hTMFgwKGGdx0D4lv7_NUy5Hzup5MDFdS9LY-y7_adL
To quote that vendor:  "Drafting templates, also known as drawing stencils, are the secret weapon for precision in technical drawing."

[tggzzz]

To quote that vendor:  "Drafting templates, also known as drawing stencils, are the secret weapon for precision in technical drawing."

A famous Mandy Rice-Davis response is appropriate: "well, they would say that, wouldn't they"

https://en.wikipedia.org/wiki/Well_he_would%2C_wouldn't_he%3F

[Analog Kid]

Hey, I still have my IBM flowcharting template:



Does anyone still draw flowcharts? I do occasionally. Very useful for certain situations where it's hard to otherwise visualize a process flow (hence the name).

[Analog Kid]

Here's another template I have that I've never used. Looks pretty useful if you're dealing with network stuff:

[coppice]

Hey, I still have my IBM flowcharting template:

(Attachment Link)

Does anyone still draw flowcharts? I do occasionally. Very useful for certain situations where it's hard to otherwise visualize a process flow (hence the name).

I think I still have one of those, and a selection of DoD logic gate stencils. Ah, the bad old days before schematic capture.

[Zero999]

My two biggest frustrations are:
1) People who claim metric for dimensions is more logical; and

Metric is more logical, for the simple reason that every scale is related by powers of ten, whereas we have 12 inches to a foot, 3 feet to a yard, 1760 yards to a mile, etc.  However, there is no advantage in using metric for PCB design because that uses decimal inches (eg 1.27 inches).  No feet and yards there.

I'm comfortable with both metric and imperial. It doesn't bother me and I can remember the most common conversions.

Here's another one, regarding schematics:
What Euro-genius decided it was a good idea to use blank rectangles for resistors, instead of a proper (zigzag) resistor symbol?

(Attachment Link)

I prefer the rectangles. I'm terrible at drawing, so my resistors and inductors tend to look similar. It's much easier to just draw a box. I believe the square form comes from carbon composion resistors and the zig-zag from wire wound, but I could be wrong.

The same is true for logic gates. I can understand why some find a diferent shape for each gate is helpful, but a box with a symbol is much easier to draw.

Before schematic capture software, I had a set of inexpensive plastic drawing templates with good patterns for resistors, capacitors with straight and/or curved plates, inductors, transformers with cores, normal active devices, the usual logic gates, etc.  My usual one was small enough to fit in a shirt pocket.
For mechanical drawing, I had other ones with hexagons, circles, ellipses, and some mechanical fasteners.
I keep the templates in a desk drawer, next to my drafting triangles, for emergencies.

Yes, I've seen those stencils, but haven't used them. Although CAD existed, when I was at college, it still wasn't routinely used on the course and I still often draw schematics by hand.

[tggzzz]

Yes, I've seen those stencils, but haven't used them. Although CAD existed, when I was at college, it still wasn't routinely used on the course and I still often draw schematics by hand.

There were 2.5 CAD programs available to me at university.

ICAP and ITAP were local equivalents of Spice small signal and transient analysis.

The 0.5 was the, ahem, word processor some people used to write their final year project report. Too many people wanted to do that so you had to make bookings to use the PDP11 text editor at 3am.

I couldn't be bothered, so I wrote it out longhand, literally cut and pasted paragraphs together, and paid a secretary to type it.

Ah, the bad old days.

[coppice]

A shoutout here for OrCAD, which got schematic capture onto thousands of desks, and really started to kill off the plastic component template, and mylar sheets.

[tggzzz]

A shoutout here for OrCAD, which got schematic capture onto thousands of desks, and really started to kill off the plastic component template, and mylar sheets.

I really liked the MSDOS version. People who were using Mental Mentor Graphics couldn't believe that you didn't need a mouse.

Never tried the PCB layout side, though; I handed the netlist to a local PCB house, and gave hints about layout.

[Psi]

Hey, I still have my IBM flowcharting template:

(Attachment Link)

Does anyone still draw flowcharts? I do occasionally. Very useful for certain situations where it's hard to otherwise visualize a process flow (hence the name).

We do at work for documentation of all the important core logic in the firmware (medical industry).

draw.io is a good free tool if you just want to throw a flowchart together yourself.

[coppice]

Does anyone still draw flowcharts? I do occasionally. Very useful for certain situations where it's hard to otherwise visualize a process flow (hence the name).

I think that depends on what you call a flow chart. The traditional IBM stencil type are pretty rare today, but there are plenty of ways people express the same thing in a different manner. Even by the early 70s huge numbers of people had abandoned flowcharts and moved to something looking more like code, using names like Program Description Language (PDL). Flow charts just take too much space, and as soon as the problem gets a little complex you don't see enough on a single page to properly follow the flow.

[jmelson]

A shoutout here for OrCAD, which got schematic capture onto thousands of desks, and really started to kill off the plastic component template, and mylar sheets.

UGH, I started with Orcad.  Yes, it was pretty good at simple stuff, but the method of creating a new schematic symbol was REAL dark ages.  You entered a string of ASCII * characters and spaces to fill out a rectangle.  Shudder!
But, the schematic entry was easy and the PCB layout wasn't bad.  I later went to Protel ADV. Schematic and PCB, then Accel and then Protel 99 SE, which I still use.
Jon