Electronics oddities we still have to live with - Page 1
Forum section: electronics / general

author: VK3DRB
author_rank: Super Contributor
timestamp: December 12, 2024, 10:06:54 am
content: Why do electronics people in Australia still call the AC mains 240V, when it is 230V +10%, -6%. In Australia, all states/territories have transitioned to 230 V standards.Why is it we still use the archaic imperial system in PCB design, when almost all the world moved to metric decades ago? I do PCB schematics and layout in metric always, but my schematic grid is 2.54mm (0.1") to avoid the dangerous off-grid errors. My Gerbers and drill lists are all in metric.Why do some component vendors (usually American) provide mechanical drawings only with imperial measurements?Why don't mechanical drawings in datasheets always reference everything to one origin datum point rather than having annoying time wasting measurements all over the shop? I suspect the authors had never made a component in Altium.Why don't some component manufacturers provide 3D step file models? If I have to choose a part, often those who have a 3D model is the deal maker, assuming other important parameters are equal.Why can't electronics engineers disco dance?Any other oddities we electronics people still have to live with, other than ourselves?

author: woofy
author_rank: Frequent Contributor
timestamp: December 12, 2024, 10:56:06 am
content: Quote from: VK3DRB on December 12, 2024, 10:06:54 amI agree, that is infuriating.I've even seen connector footprint drawings where there is no route from one reference to another.

author: jpanhalt
author_rank: Super Contributor
timestamp: December 12, 2024, 11:01:00 am
content: My two biggest frustrations are:1) People who claim metric for dimensions is more logical; and2) People who thing metric is more accurate.

author: Psi
author_rank: Super Contributor
timestamp: December 12, 2024, 11:01:33 am
content: Why do capacitors always have a line indicating negative except when it's a tantalum which have a line for positive.

author: tom66
author_rank: Super Contributor
timestamp: December 12, 2024, 11:37:19 am
content: Quote from: woofy on December 12, 2024, 10:56:06 amIt is infuriating, but speaking to a mechanical engineer, the idea is to avoid a possible conflict in the drawing by making everything dependent upon only one other datum. Otherwise it is possible to create conflicting dimensions.In the world of CAD though, surely such conflicts could be validated out by the software. And perhaps a list of absolute coordinates relative to some other coordinate could be provided. Having to draw a microSD connector out using these dimensions was incredibly painful.

author: SteveThackery
author_rank: Super Contributor
timestamp: December 12, 2024, 05:49:19 pm
content: Quote from: jpanhalt on December 12, 2024, 11:01:00 amMetric 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.Quote from: jpanhalt on December 12, 2024, 11:01:00 amReally? 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.

author: AVGresponding
author_rank: Super Contributor
timestamp: December 12, 2024, 06:14:32 pm
content: Quote from: VK3DRB on December 12, 2024, 10:06:54 amSpeak for yourself; I won first prize for it at the school end-of-term disco when I was eleven

author: tggzzz
author_rank: Super Contributor
timestamp: December 12, 2024, 06:39:02 pm
content: Quote from: VK3DRB on December 12, 2024, 10:06:54 amI would hope and expect the mechanical measurements reflect the manufacturing techniques and hence the manufacturing tolerances.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 12, 2024, 06:41:51 pm
content: Quote from: AVGresponding on December 12, 2024, 06:14:32 pmThat was then; this is now; can you still get down and boogie?And what's with that precious non-standard text color you insist on using?

author: coppice
author_rank: Super Contributor
timestamp: December 12, 2024, 06:42:14 pm
content: Quote from: tom66 on December 12, 2024, 11:37:19 amYou forgot the major factor. Good dimensioning includes tolerances, and the tolerances in various parts of a product are not all to a single reference point.

author: TimFox
author_rank: Super Contributor
timestamp: December 12, 2024, 06:46:14 pm
content: Australians (and other members of the Commonwealth) may use imperial measurements, but in America we use "US conventional units".There are some differences between the two systems, but both are defined in terms of SI metric units.The Empire is long gone, but the United States are still here.The 0.1 inch = 2.54 mm grid isn't hard to use.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 12, 2024, 06:47:11 pm
content: 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?

author: Analog Kid
author_rank: Super Contributor
timestamp: December 12, 2024, 06:49:20 pm
content: Quote from: TimFox on December 12, 2024, 06:46:14 pmThere; FIFY.

author: coppice
author_rank: Super Contributor
timestamp: December 12, 2024, 06:51:01 pm
content: I don't think "Electronics oddity we still have to live with" is a nice way to describe someone in this forum.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 12, 2024, 06:54:18 pm
content: Hmm; anyone in particular you have in mind? or is "someone" here used in the general sense?

author: jpanhalt
author_rank: Super Contributor
timestamp: December 12, 2024, 07:00:53 pm
content: Quote from: SteveThackery on December 12, 2024, 05:49:19 pmI won't delve deeply into #1. Seems to me dimensions that are easily divisible by 2,3,4, other numbers, and decimal units are more logical and useful. What divisions one uses is a choice in our system, but not in metric. The metric basic unit is no more logical than our basic unit. Both are arbitrary.As for #2. Yes, I have heard people at work say metric was more accurate. Even if they really meant precise, it is no more precise either. In a practical sense, if you look at dials on manual machines, the smallest division in metric is usually 0.05mm. On our machines, it is 0.001", or about twice as precise, assuming the numbers mean anything.I mentioned it as an odditie, not to argue about metric v. imperial/American. In my own life, I use what's conventional and convenient, e.g., in physical sciences, metric; and in the garage and kitchen psi, ft-lb, inches (both decimal and fractional), tablespoons, etc.

author: TimFox
author_rank: Super Contributor
timestamp: December 12, 2024, 07:02:30 pm
content: Quote from: Analog Kid on December 12, 2024, 06:49:20 pm"States" is plural."The United States of America" is singular.

author: TimFox
author_rank: Super Contributor
timestamp: December 12, 2024, 07:04:40 pm
content: Quote from: coppice on December 12, 2024, 06:51:01 pm"Oddity" is a feature or a person. "Oddball" is an insult to a person.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 12, 2024, 07:04:58 pm
content: Quote from: TimFox on December 12, 2024, 07:02:30 pmBut "the United States" is not; it's generally recognized by USAns (of which you are one) as a single entity, therefore singular.The UKOGBANIs treat it as plural, not us.

author: TimFox
author_rank: Super Contributor
timestamp: December 12, 2024, 07:06:47 pm
content: Quote from: Analog Kid on December 12, 2024, 06:47:11 pmI always use the "zigzag" for resistors, since is is suggestive of the function, just as the loops are suggestive of coils (inductors).The blank rectangle is useful for arbitrary components or impedances.Unfortunately, the rectangle is considered standard in Europe.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 12, 2024, 07:11:35 pm
content: Quote from: jpanhalt on December 12, 2024, 07:00:53 pmYes. One area where I find our (non-metric) system much easier to deal with is carpentry and woodworking, at least for most work where the highest precision is 1/16". Much easier to deal with a sheet of plywood that's 4' x 8', rather than the entirely unwieldy 2440mm x 1220mm. And divisions in working with wood are not easier in units of 10; even dividing a space into equal subunits is easily done in non-metric units by well-known tricks.Of course, I realize that part of my preference here is due to growing up using that system of measurement, but it still feels more suitable to me than the alternative.

author: TimFox
author_rank: Super Contributor
timestamp: December 12, 2024, 07:17:10 pm
content: Quote from: Analog Kid on December 12, 2024, 07:04:58 pmThere are other "United States", including Mexico (officially United Mexican States in translation).The "United States of America", abbreviated USA, is the specific term for the country of which I am a citizen.The US Constitution seems to have only one clause in which the plural or singular is relevant. Usually, "United States" is followed by "shall" which does not distinguish singular and plural. However,"Treason against the United States, shall consist only in levying War againstthem, or in adhering to their Enemies" (Article III, section 3)

author: Analog Kid
author_rank: Super Contributor
timestamp: December 12, 2024, 07:26:56 pm
content: Quote from: TimFox on December 12, 2024, 07:17:10 pmYes, yes, but what you're arguing here is pure sophistry. Everyone, at least everyone west of Nova Scotia, recognizes "the United States" or "the US" as "the United States of America", so there's no need for the fine distinction you're proposing.

author: themadhippy
author_rank: Super Contributor
timestamp: December 12, 2024, 07:35:10 pm
content: QuoteCause were either busy out the back trying to kick some piece of kit back into life or too knackered after being up half the previous evening rebuilding stuff that mr dj blew up at the last gig but only remembered last night.One oddity that me and many others have pondered is why do ceeform ratings jump instead of flowing nicely, 16A, 32A yep fine,but then 63A and 125A,why not 64A and 128A.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 12, 2024, 08:07:48 pm
content: Like shutter speeds that go 1-2-4-8-15-30-60-125-250-500-1000? Although that's always made sense to me ...

author: TimFox
author_rank: Super Contributor
timestamp: December 12, 2024, 08:19:24 pm
content: Quote from: Analog Kid on December 12, 2024, 07:26:56 pmAnd you are being pedantic. Since Article III, Section 3 calls "the United States" plural, then so may I.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 12, 2024, 08:24:50 pm
content: Quote from: TimFox on December 12, 2024, 08:19:24 pmBut Tim, that was written back in the 18th century.Do you still refer to it as the "Conftitution of the Unitedftates"?

author: TimFox
author_rank: Super Contributor
timestamp: December 12, 2024, 08:30:51 pm
content: Quote from: Analog Kid on December 12, 2024, 08:24:50 pmThe letter that you find amusing is not "f", it is a "long s" which differs from an "f".Typically, the long s is used in the middle of a word, and the short s (which is the only one you use) is used at the end of a word.https://blog.thepreservationlab.org/2024/01/what-say-you-a-brief-look-at-the-long-s-and-its-usage

author: Analog Kid
author_rank: Super Contributor
timestamp: December 12, 2024, 08:34:37 pm
content: Quote from: TimFox on December 12, 2024, 08:30:51 pmI know, I was just needling you.I still to this day can't help mentally pronouncing it "the conftitution of the united ftates" whenever I see that writing (what, did the Founding Fathers all have speech defects?). I do find it amusing from my 21st C. vantage point.

author: VK3DRB
author_rank: Super Contributor
timestamp: December 13, 2024, 07:07:52 am
content: Quote from: Psi on December 12, 2024, 11:01:33 amVery good question. I see no logic in it. But I learn the lesson many years ago when I reversed a tantalum thinking the strip was negative. Burnt a hole right through the PCB and set off the fire alarm.

author: VK3DRB
author_rank: Super Contributor
timestamp: December 13, 2024, 07:17:54 am
content: Quote from: Analog Kid on December 12, 2024, 06:47:11 pmActually it is a good idea, because I can embed the resistor package inside the resistor symbol. Here is an example of 0402's. It saves real estate on the schematic.

author: VK3DRB
author_rank: Super Contributor
timestamp: December 13, 2024, 07:22:59 am
content: Quote from: TimFox on December 12, 2024, 07:06:47 pmAnd Australia. It is olde school to use the zig zag. As I mentioned above the rectangle does have benefits.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 13, 2024, 07:42:35 am
content: Quote from: TimFox on December 12, 2024, 08:19:24 pmThe United State of America is a Federation, although they state "united" in the name, so it seems that it has a degree of duality.The Commonwealth of Australia on the other hand, although it is also a Federation, is referred to as "it", or sometimes as "She"-----go figure!

author: vk6zgo
author_rank: Super Contributor
timestamp: December 13, 2024, 07:45:19 am
content: Quote from: Analog Kid on December 12, 2024, 06:47:11 pmBack in the day, draughtsmen drew all schematics by hand.It was much easier to produce a rectangle, instead of the zigzag.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 13, 2024, 08:02:21 am
content: Quote from: TimFox on December 12, 2024, 06:46:14 pmImperial measures are long gone in Australia for most everyday commerce, the UK are still using some measures, & a lot of "nuts n' bolts" from India are still Imperial.Of all the measures, the only real difference between Imperial & US conventional is volume, where the former has pints, quarts, gallons etc larger than the latter.As a result, an Imperial "44 gallon drum" is a US "55 gallon drum.On the other hand, such a drum would be labelled as a "200 litre" drum, which makes conversion easier between a country using Imperial & one using US measures.As both countries also deal with Metric countries, they will each only need their existing conversion table.

author: Zoli
author_rank: Frequent Contributor
timestamp: December 13, 2024, 08:06:07 am
content: Quote from: Analog Kid on December 12, 2024, 06:47:11 pmFilm vs wire wound.

author: Brumby
author_rank: Unknown
timestamp: December 13, 2024, 08:34:17 am
content: Quote from: vk6zgo on December 13, 2024, 07:45:19 amWhen I draw a circuit freehand, I can draw a zig-zag resistor in one continuous movement.I'm a big fan of a symbol being representative of the function. To me, a box doesn't suggest anything in particular in itself - only what is defined for it. To me, that is a step of abstraction your brain has to bridge before you can start "seeing" the circuit in full.

author: VK3DRB
author_rank: Super Contributor
timestamp: December 13, 2024, 08:47:04 am
content: Quote from: Zoli on December 13, 2024, 08:06:07 amWire-wound are quite inductive and unsuitable for a lot of RF applications. Plus they are relatively huge. I used mainly 0402 size resistors in most of my work, which are the most common these days in general, occasionally 0603 and others, and even 0201 on occasions. They are all film. 0402's are the practical limit of my hand soldering skills, although I have hand soldered 0201s... very time consuming and difficult for me to do damned 0201s.

author: Zoli
author_rank: Frequent Contributor
timestamp: December 13, 2024, 08:55:45 am
content: Quote from: VK3DRB on December 13, 2024, 08:47:04 amI came over schematics(TV, IIRC) where the wire wound resistor was drawn as zigzags, and the film resistor as rectangle.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 13, 2024, 10:12:54 am
content: On the other hand, it is possible to put in too many zigs and zags when drawing resistors, as in the old-tyme style:

author: Krotow
author_rank: Regular Contributor
timestamp: December 13, 2024, 11:07:48 am
content: Quote from: VK3DRB on December 13, 2024, 07:17:54 amExactly this. Some also insert 1 or 3 zeros for 0 Ohm resistors at the middle of the rectangle. Pretty informative, especially in large schematic.I however have a sympathy for zigzag resistor representation. A little easier when someone draw the circuit by hand. Also first resistors in physicist labs were wire-wound ones so resemblance is very clear. From functional aspect resistors should be represented as little flamesQuote from: VK3DRB on December 13, 2024, 08:47:04 am0201s can be a pain. And not due to soldering skill (pretty easy doable when you have whatever microscope), but because they are veeeeery easy to lose. Exhale in wrong direction will send your components to whatever direction and I guarantee that you will not find them anymore. My work room have a dozen of these somewhere scattered around.

author: TimFox
author_rank: Super Contributor
timestamp: December 13, 2024, 03:33:54 pm
content: Quote from: vk6zgo on December 13, 2024, 07:42:35 amThe USA is a "Federal Republic". The Constitution, ratified in 1788, replaced the original "Articles of Confederation" which had established a Federation.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 13, 2024, 03:52:19 pm
content: Quote from: woofy on December 12, 2024, 10:56:06 amNot to mention footprints showing distances between pad edges, not centres

author: nctnico
author_rank: Super Contributor
timestamp: December 13, 2024, 03:59:03 pm
content: Quote from: VK3DRB on December 12, 2024, 10:06:54 amWhy are relay footprints drawn in bottom view (instead of top-view)?Why isn't there a connector which is perfectly right for the project at hand?And I second the frustration about footprint measurements not having an origin. This seems to be a problem with mechanical people in general. Every time I get a drawing for an odd-shaped PCB, I need to hunt for the origins, circle centers, etc in order to create the board outline.

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2024, 04:34:57 pm
content: Quote from: Zoli on December 13, 2024, 08:06:07 amthis is nonsense, most film resistors are spirals.It only makes sense for a composition resistor. Ceramic, carbon or possibly a small fraction of film resistors... exotic ones.

author: tggzzz
author_rank: Super Contributor
timestamp: December 13, 2024, 04:53:30 pm
content: Quote from: nctnico on December 13, 2024, 03:59:03 pmThey often used valve bases, and there was no point of having a top view of valve pins.

author: ebastler
author_rank: Super Contributor
timestamp: December 13, 2024, 05:08:19 pm
content: Quote from: Analog Kid on December 12, 2024, 06:41:51 pmJust another holdover from when he was eleven.

author: TimFox
author_rank: Super Contributor
timestamp: December 13, 2024, 05:28:27 pm
content: Quote from: vk6zgo on December 13, 2024, 08:02:21 amUntil 1959, when the US went metric but forgot to tell anyone, the US conventional inch was very slightly different from the Imperial inch.The older US definition was 1 meter = 39.37 inch, but the Imperial and newer US definition is 1 inch = 2.54 cm (both ratios defined as exact).This was done to harmonize US and UK inches. The difference is approximately 2 ppm.

author: wraper
author_rank: Unknown
timestamp: December 13, 2024, 05:33:53 pm
content: Quote from: jpanhalt on December 12, 2024, 11:01:00 am

author: TimFox
author_rank: Super Contributor
timestamp: December 13, 2024, 05:40:29 pm
content: Quote from: tggzzz on December 13, 2024, 04:53:30 pmVacuum-tube pins were always numberedclockwiseseen from the bottom (where the components and wires went).Clockwise from the bottompersists into DIP IC pinouts and most (not all) similar semiconductor-package pinouts.

author: wraper
author_rank: Unknown
timestamp: December 13, 2024, 05:42:36 pm
content: Quote from: Analog Kid on December 12, 2024, 06:47:11 pmI'm European and I like them rectangle, not that sawtooth garbage.

author: SteveThackery
author_rank: Super Contributor
timestamp: December 13, 2024, 05:51:12 pm
content: Quote from: TimFox on December 13, 2024, 05:28:27 pmHey, some irritating nitpicking coming up! I'm pretty certain it is 25.4mm, not 2.54cm. Can I have the "Pedant of the Day" award?

author: tggzzz
author_rank: Super Contributor
timestamp: December 13, 2024, 05:55:48 pm
content: Quote from: SteveThackery on December 13, 2024, 05:51:12 pmThat's reserved for someone asking whether X is "hard metric" or "soft metric".Hard metric ceramic tiles are, say, 150mm, whereas soft metric tiles are 154mm. Convert the latter into Imperial units, and you'll see why.

author: Zoli
author_rank: Frequent Contributor
timestamp: December 13, 2024, 06:16:22 pm
content: Quote from: coppercone2 on December 13, 2024, 04:34:57 pmOf course, especially the vast majority of the currently sold ones: chip SMD/sarcasmOn the more serious note, the film resistors precede the laser trimming, which gave the round-spiral form of the current THD/MELF resistors. Long time ago(80's), I worked with flat, untrimmed THD thick film resistors.And to answer the question in your other tread: look for non-inductive thick-film resistors.

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2024, 06:47:17 pm
content: look at what non inductive means, it is often just cut a little differentlyI meant uncut. No trim.

author: TimFox
author_rank: Super Contributor
timestamp: December 13, 2024, 06:51:34 pm
content: Quote from: SteveThackery on December 13, 2024, 05:51:12 pmUtter nonsense. 25.4 mm = 2.54 cm = 0.0254 m EXACTLY.The actual formal documenthttps://www.nist.gov/system/files/documents/2017/05/09/frn-59-5442-1959.pdfdefined the new US conventional length in terms of the yard, which is subdivided in the same manner as 1 yard = 36 inch.

author: TimFox
author_rank: Super Contributor
timestamp: December 13, 2024, 06:56:15 pm
content: Quote from: coppercone2 on December 13, 2024, 04:34:57 pmNo TH film resistors are spirals. Many are helices. There is a difference between a spiral and a helix.There are interesting TH film resistors, such as Caddock MS non-inductive unitshttps://www.caddock.com/online_catalog/mrktg_lit/TypeMS.pdfthat use a "serpentine" pattern to minimize inductance.

author: Zoli
author_rank: Frequent Contributor
timestamp: December 13, 2024, 07:00:11 pm
content: Quote from: coppercone2 on December 13, 2024, 06:47:17 pmExactly:SOME(not all) of the non-inductive thick-film resistors are non-trimmed; IIRC, there is a company which offers non-trimmed thick film SMD resistors, but don't remember the name.

author: coppercone2
author_rank: Super Contributor
timestamp: December 13, 2024, 07:44:23 pm
content: Quote from: TimFox on December 13, 2024, 06:56:15 pmi consider serpentine a spiral its just planar. If you follow the path, it ends up being a wave form of some kind. the box is pretty clear that its uniform. The zig zag drawing is accurate to most resistors unless their composition or speciality uncut ones. A single notch anywhere turns it from _ into a U of some kind. A composition resistor is pretty accurate to a box shape, while any cut resistor is a zig zag of some kind.maybe we should just draw what the resistor actually looks like in the diagram.The problem is that wire wound ones look identical to air core inductors. Perhaps color can indicate material, if its copper or lossy.

author: TimFox
author_rank: Super Contributor
timestamp: December 13, 2024, 07:58:19 pm
content: I consider the zig-zag pattern an indication offunction, not geometry.The rectangle merely indicates an object with two wires, not very specific.In mathematics, a spiral is normally a planar figure: e.g., a regular spiral has a local radius proportional to angle and a logarithmic spiral has a local radius that increases exponentially with angle (the angle is proportional to the logarithm of the radius).

author: Analog Kid
author_rank: Super Contributor
timestamp: December 13, 2024, 08:40:40 pm
content: There's absolutely no need to differentiate resistortypes(i.e., wirewound, composition, power, etc.) by use of different schematicsymbols. So far as the schematic is concerned, a resistor is a resistor. Any differences are pointed out on the schematic (or on the parts list) as text descriptions: "5W ww", "2W 1%", etc. No need to add more confusion to what's already a plethora of symbols to be read.And the zigzag catches the eye--"ah yes, that's a resistor"--more readily than an anonymous rectangle does.

author: mikerj
author_rank: Super Contributor
timestamp: December 13, 2024, 09:47:49 pm
content: Quote from: Analog Kid on December 13, 2024, 08:40:40 pmBecause that's what you are used to. It's like the ANSI/DIN/IEC logic gate symbols, if you have exclusively used one for a long time then reading a schematic that uses a different standard may not immediately intuitive.Mechanical drawings don't reference everything to one origin because it would make tolerancing very difficult. In the vast majority of designs the distance between specific features is of significant importance and may be require much tighter tolerances than the positioning of those features in relation to other, unrelated features.

author: Gregg
author_rank: Super Contributor
timestamp: December 13, 2024, 10:42:27 pm
content: Those who draw resistors as rectangles should at least insert the proper color bands for us old timers.

author: TimFox
author_rank: Super Contributor
timestamp: December 13, 2024, 11:01:28 pm
content: Quote from: mikerj on December 13, 2024, 09:47:49 pmHaving dealt with systems from the US, Europe, and Asia during my career, I certainly recognize the rectangle as a symbol for a resistor.However, the zigzag for resistors, loopy-loops for inductors, and parallel bars for capacitors are better specific codes for their functions.

author: coppice
author_rank: Super Contributor
timestamp: December 13, 2024, 11:37:05 pm
content: Quote from: TimFox on December 13, 2024, 11:01:28 pmAs a European who was working when the change from zig-zags to boxes happened, I can say our reaction was WTF!

author: Analog Kid
author_rank: Super Contributor
timestamp: December 13, 2024, 11:45:56 pm
content: Quote from: coppice on December 13, 2024, 11:37:05 pmWas that around the same time "they" changed mhos to Siemens?

author: Bobson
author_rank: Regular Contributor
timestamp: December 14, 2024, 12:15:47 am
content: Quote from: Analog Kid on December 13, 2024, 11:45:56 pmAnd kilocycles to kiloHertz.

author: tggzzz
author_rank: Super Contributor
timestamp: December 14, 2024, 12:20:36 am
content: Quote from: Bobson on December 14, 2024, 12:15:47 amAnd Jars to Farads.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 14, 2024, 12:23:45 am
content: Quote from: Brumby on December 13, 2024, 08:34:17 amI was brought up on "zigzags" & like you, they are my default when I draw schematicsDraughtsmen are "a different kettle of fish", as they don't draw "freehand".Their drawings are formal, they drew hundreds of them, so they used drawing aids & so on.I once had a "drawing aid" with various shapes, including "zigzag" resistors-----the result of using such aids is a worse zigzag than you can do by hand.Another complication in Europe is the older German predilection for drawing transformer windings as "zigzags", or sometimes "square wave" shapes.The rectangles were standardised in many countries worldwide, but the reasons for them are no longer fully valid, as computers can draw as many perfect "zigzags" as your heart could desire.

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 14, 2024, 12:32:59 am
content: Quote from: wraper on December 13, 2024, 05:42:36 pmDitto, but you won't stop them from using these zigzags, ".1uF" for "100nF" and inches everywhere. Oh well.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 14, 2024, 12:49:51 am
content: Quote from: SiliconWizard on December 14, 2024, 12:32:59 amSo tell us, why is 100nF superior to .1μF?I actually kinda hatenF. Have to take out paper and pencil every damn time I see that to figure out what the value is. (Old skool here.)Hey, at least we're no longer using "mmF" ... or calling them "condensers" ...

author: vk6zgo
author_rank: Super Contributor
timestamp: December 14, 2024, 01:06:34 am
content: Quote from: coppercone2 on December 13, 2024, 06:47:17 pm"Non-Inductive" resistors is an old term for wirewound resistors which were specially wound so as the inductance was largely self cancelled. That works up to around 100kHz---above that they are still inductive enough to cause problems.Carbon composition resistors were much closer to Non-inductive, although they had other problems.Early "carbon film" resistors were trimmed using a lathe-like device, & were inductive.Many years ago, the Instructor at Tech School demonstrated the difference between a daggy old composite & a nice new Philips carbon film resistor, using a "Q" meter.To our surprise, the carbon composite came out on top, with the carbon film looking more inductive than resistive at HF frequencies.

author: SteveThackery
author_rank: Super Contributor
timestamp: December 14, 2024, 01:07:04 am
content: Quote from: Analog Kid on December 14, 2024, 12:49:51 amIt's just easier and less error-prone to stick to integer values. It is an ISO convention to use intervals of 10^3, which is great because it is totally consistent:milli (10^-3), micro (10^-6), nano, pico, femto, ato (10^-18)kilo (10^3), mega, giga, tera, peta, exa (10^18)I realise you know all that, but an integer comprising one to three digits followed by the relevant suffix seems like a really clean and elegant system, which is why I wrote it out. After all, you are happy with picoFarads, so why not nanoFarads?

author: Analog Kid
author_rank: Super Contributor
timestamp: December 14, 2024, 01:33:47 am
content: Quote from: SteveThackery on December 14, 2024, 01:07:04 amNow that actually makes sense.But I still think that a lot of electronics conventions like these are on account of undue paranoia, like the fear of Xeroxes:I've seen that as the justification for that silly "xRy" convention (e.g., 6R8K instead of 6.8K), because people are afraid of that little dot disappearing when the schematic gets copied a few times. I suppose that might have happened back in the Stone Age.

author: NiHaoMike
author_rank: Super Contributor
timestamp: December 14, 2024, 02:06:58 am
content: I'm surprised nobody mentioned how the arrow in the symbol for a diode or bipolar transistor points opposite the way the electrons actually flow. It got corrected for the symbol for a MOSFET, then "uncorrected" for the symbol for an IGBT...Quote from: Analog Kid on December 14, 2024, 01:33:47 amI still follow that convention when drawing schematics by hand. The dot is prone to getting smudged away on paper. Such a practice is obsolete when drawing it on a tablet, hopefully whatever software that comes to convert those hand drawn schematic images to proper schematic files will understand that...I have also seen that convention used on higher power resistors.Quote from: SteveThackery on December 14, 2024, 01:07:04 amThe whole "nanophobia" in capacitor values is something I don't understand. 2.2nF is much more readable than 0.0022uF.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 14, 2024, 02:20:50 am
content: Quote from: NiHaoMike on December 14, 2024, 02:06:58 amWellll ... the consensus seems to be among the electronics "community" that we visualize current flow in the "conventional" sense (i.e., from positive to negative), not in the strict physics sense of electron flow.Which, BTW, apparently doesn't work at all as most people think of it: I've read (can't put my finger on the exact reference at the moment) that in reality, electrons can take a very long time to actually travel through conductors; years, in some cases if I remember correctly.Have to dig up some stuff from the intertubes on that now.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 14, 2024, 02:33:10 am
content: Quote from: SteveThackery on December 13, 2024, 05:51:12 pmThe Metrication Board in OZ was very hot on always using mm, instead of the "deprecated" cm.They didn't even like metres much---so if I want to buy a 2.5 metre piece of wood, I have to order a 2500mm piece.The idea seems to be tied up with people maybe confusing 2.5m with 25m due to the decimal point.Of course, we pay for things with decimal currency, & nobody makes mistakes.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 14, 2024, 02:36:31 am
content: Quote from: tggzzz on December 13, 2024, 05:55:48 pmA lot of tiles in Australia are 180mm x 180mm.Hold them up against an old 6"x 6" tile & you are battling to see the difference.

author: TimFox
author_rank: Super Contributor
timestamp: December 14, 2024, 03:07:12 am
content: During my graduate studies in physics, most dimensions (in that ballpark of sizes) were calculated in cm, but the machine shop worked in mm.Both of us could handle it.Separately, a useful way to abbreviate 6800\$\Omega\$ is 6K8, not to be confused with the vacuum tube of the same name.

author: Analog Kid
author_rank: Super Contributor
timestamp: December 14, 2024, 03:11:45 am
content: Quote from: vk6zgo on December 14, 2024, 02:33:10 amI'm going to coin a new term here: punctophobia.(Not to be confused with Punktophobia, which is irrational fear of German radio equipment.)

author: mwb1100
author_rank: Frequent Contributor
timestamp: December 14, 2024, 06:10:54 am
content: Regardless of the merits or lack of merit for various systems of units, the situation of having more than one system in widespread use is a problem:-Gimli Glider-Mars Climate OrbiterOn a less epic scale, when I'm getting measurements for furniture items that my wife wants some descriptions provide the measurements in US customary units and some in metric. Therefore I end up with notes that I need to put far too much work into to sort out. I don't think this ever made it through to getting a non-fitting piece of furniture, but it's possible that I've suppressed the memory. I can't recall a specific instance, but I'm pretty sure I have made cuts (wood, paper, whatever) using the wrong units. Nothing of much consequence to life, limb, or finances - irritating nonetheless.On a tangent,@wraper's SNL clip reminds me of this observation made years ago by Abe Simpson:Quote(Abe is spending WAAAAY too much on fuel)

author: forrestc
author_rank: Unknown
timestamp: December 14, 2024, 07:14:03 am
content: Quote from: NiHaoMike on December 14, 2024, 02:06:58 amThat arrow isn't indicating what you think it is. The way oversimplified (and probably technically inaccurate if you're a pedant) is that the center "terminal" with the arrow on it is actually the base (or substrate) of the MOSFET. In three terminal mosfets, the base is tied to the source, and the PN junction between the substrate and the source and drain forms a diode - which is what that arrow and the connection typically shown in the schematic symbol is indicating, not the direction of current flow through the device when it is "on". Or stated differently: it's indicating the body diode.If you find a schematic symbol that doesn't have the three "internal terminals" shown on the schematic and have it drawn more like a transistor, you'll find the arrow matches the direction you'd expect on a bipolar transistor.You can, on occasion, find a 4 terminal mosfet, in which case the substrate is on another pin and needs to be tied to source for it to work as expected. The schematic for that just brings out the base/substrate to another pin.One other note that people miss is that the diode commonly drawn across the diode (connecting to source and drain) indicates that the body diode is rated for repeated avalanche operation. Or, if you just want to think about it more "schematically", it's just like a zener was placed across the FET. But-one shouldn't trust that the correct symbol was chosen that matches the device.

author: fzabkar
author_rank: Super Contributor
timestamp: December 14, 2024, 08:18:53 am
content: Quote from: mwb1100 on December 14, 2024, 06:10:54 amhttps://www.google.com/search?q=40+rods+per+us+hogshead+in+metres+per+litre

author: tom66
author_rank: Super Contributor
timestamp: December 14, 2024, 09:47:06 am
content: On the subject of cursed units ...

author: tggzzz
author_rank: Super Contributor
timestamp: December 14, 2024, 10:10:15 am
content: Quote from: vk6zgo on December 14, 2024, 02:36:31 amI know things are bigger in Australia, but over here 6" is ~153mm.That doesn't matter on its own, but can be noticeable when aligning a run of tiles with something that is hard metric. A really bad case is creating pattern by intermixing hard and soft metric!

author: vk6zgo
author_rank: Super Contributor
timestamp: December 14, 2024, 10:58:14 pm
content: Quote from: tggzzz on December 14, 2024, 10:10:15 amDoh!!Of course you are right!Somewhere down the line, I had to work with some trim materials (perhaps rectangular tiles) with a standard length of 180mm, & that size was "stuck in my head".Still no excuse, though, as I have a set of calipers to hand, as well as my ancient HP22s which does inch to cm conversions.My problem at home is that everything was built using Imperial measures.Even so, with tiles, the 6" to 150mm tile sizing thing is not a major problem, but the fact that imported tiles from the PRC etc., don't come in the many colour shades which were common in the 1960s & '70s is.

author: newbrain
author_rank: Super Contributor
timestamp: December 17, 2024, 02:24:56 pm
content: Quote from: Analog Kid on December 14, 2024, 01:33:47 amWell, it was a well justified fear. unfortunately using 6R8 instead of 6.8 wouldn't have helped.https://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres_are_switching_written_numbers_when_scanning

author: nctnico
author_rank: Super Contributor
timestamp: December 17, 2024, 03:17:56 pm
content: Quote from: newbrain on December 17, 2024, 02:24:56 pmWow... just wow... can't believe that happened.

author: pardo-bsso
author_rank: Frequent Contributor
timestamp: December 17, 2024, 03:22:35 pm
content: Quote from: Analog Kid on December 12, 2024, 06:41:51 pmYes Sir, I can Boogie.

author: KE5FX
author_rank: Super Contributor
timestamp: December 17, 2024, 04:45:35 pm
content: Quote from: VK3DRB on December 13, 2024, 07:07:52 amYou can think of the stripe as the cathode marking on a diode. Tantalum caps are basically diodes with pathological amounts of Cd, which is why you can jerry-rig a non-polarized electrolytic simply by connecting two tantalums back to back.The stripe serves as a reminder that it will explode like a diode if you run enough current through it backward.

author: tom66
author_rank: Super Contributor
timestamp: December 17, 2024, 11:32:13 pm
content: Quote from: newbrain on December 17, 2024, 02:24:56 pmWow. I'd better check if we have any Xerox copiers in the office...

author: Halcyon
author_rank: Unknown
timestamp: December 18, 2024, 12:04:27 am
content: Quote from: jpanhalt on December 12, 2024, 11:01:00 amSeems like a claim made by people who don't know any better?Accuracy depends on number of decimal places. Units of measurement can be as accurate or inaccurate as you like.

author: SteveThackery
author_rank: Super Contributor
timestamp: December 18, 2024, 12:27:06 am
content: Quote from: Halcyon on December 18, 2024, 12:04:27 amActually, when discussing the number of decimal places, I think you are talking aboutprecision, rather than accuracy.I am 21 years, three months, one week, 4 days, 15 hours, 45 minutes and 38.7 seconds old.That statement is very precise butnotvery accurate.

author: Halcyon
author_rank: Unknown
timestamp: December 18, 2024, 12:28:36 am
content: Quote from: SteveThackery on December 18, 2024, 12:27:06 amYeah yeah, rub it in, you young whipper snapper.

author: tggzzz
author_rank: Super Contributor
timestamp: December 18, 2024, 12:40:53 am
content: Quote from: Halcyon on December 18, 2024, 12:28:36 amHis statement could be correct as well as being older than you

author: nctnico
author_rank: Super Contributor
timestamp: December 18, 2024, 09:54:28 am
content: Quote from: KE5FX on December 17, 2024, 04:45:35 pmI don't think I have even seen a diode explode / burn like a tantalum capacitor can. If I didn't wear glasses, I would probably be blind due to a tantalum exploding in my face. Because the stubborn designer of the board didn't put the capacitors with the polarity in a uniform direction (against my strong suggestion), the reversed tantalum wasn't noticed during inspection.

author: Siwastaja
author_rank: Super Contributor
timestamp: December 18, 2024, 11:07:43 am
content: Quote from: KE5FX on December 17, 2024, 04:45:35 pmNow that is some pretty serious mental acrobatics, reminds me of the one who claimed that diodes do not exist but we only have resistors. And of course, we can as well say that diodes are basically tantalum caps with pathologically low amounts of Cd.

author: RJSV
author_rank: Super Contributor
timestamp: December 18, 2024, 12:06:49 pm
content: First thing comes to mind, is the classic 'Chivken Head Knobs', but that's not exactly a good answer.I do think that many portions of the classic residential POWER POLE are becoming obsolete, maybe meaning more telephone service innovation. (Current residential areas there is an upper set of wires, for power delivery, and with phone stuff lower down on each pole.)I have been noticing heavy squirrel activity, up and down our local pole, and stymied as to what's attracting the small mammal presence ?Best guess is that they (squirrel) seek to peel soft bark, but they sure are on that pole pretty heavily.

author: tom66
author_rank: Super Contributor
timestamp: December 18, 2024, 12:31:12 pm
content: An interesting argument but I think the issue with considering a tantalum to be the same as a diode, is a diode's capacitance is a function of voltage bias (there is some constant capacitance due to construction, but the majority occurs under bias) whereas a tantalum capacitor would ideally have a very flat capacitance-voltage bias behaviour. There are clearly different processes at play here.

author: EPAIII
author_rank: Super Contributor
timestamp: December 20, 2024, 09:18:14 am
content: 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.Quote from: SteveThackery on December 12, 2024, 05:49:19 pm

author: watchmaker
author_rank: Unknown
timestamp: December 20, 2024, 12:01:02 pm
content: 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.

author: Zero999
author_rank: Super Contributor
timestamp: December 20, 2024, 01:59:16 pm
content: Quote from: SteveThackery on December 12, 2024, 05:49:19 pmI'm comfortable with both metric and imperial. It doesn't bother me and I can remember the most common conversions.Quote from: Analog Kid on December 12, 2024, 06:47:11 pmI 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.

author: TimFox
author_rank: Super Contributor
timestamp: December 20, 2024, 03:33:10 pm
content: Quote from: Zero999 on December 20, 2024, 01:59:16 pmBefore 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.

author: tggzzz
author_rank: Super Contributor
timestamp: December 20, 2024, 05:35:48 pm
content: Quote from: TimFox on December 20, 2024, 03:33:10 pmI still have mineI also have some Rotring drafting pens, required for a university course and never used thereafter. I wonder if I can flog them on fleabay

author: TimFox
author_rank: Super Contributor
timestamp: December 20, 2024, 05:45:14 pm
content: Quote from: tggzzz on December 20, 2024, 05:35:48 pmWith 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_adLTo quote that vendor: "Drafting templates, also known as drawing stencils, are the secret weapon for precision in technical drawing."

author: tggzzz
author_rank: Super Contributor
timestamp: December 20, 2024, 05:55:52 pm
content: Quote from: TimFox on December 20, 2024, 05:45:14 pmA 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

author: Analog Kid
author_rank: Super Contributor
timestamp: December 20, 2024, 09:28:42 pm
content: 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).

author: Analog Kid
author_rank: Super Contributor
timestamp: December 20, 2024, 09:34:58 pm
content: Here's another template I have that I've never used. Looks pretty useful if you're dealing with network stuff:

author: coppice
author_rank: Super Contributor
timestamp: December 20, 2024, 09:35:21 pm
content: Quote from: Analog Kid on December 20, 2024, 09:28:42 pmI think I still have one of those, and a selection of DoD logic gate stencils. Ah, the bad old days before schematic capture.

author: Zero999
author_rank: Super Contributor
timestamp: December 20, 2024, 10:48:32 pm
content: Quote from: TimFox on December 20, 2024, 03:33:10 pmYes, 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.

author: tggzzz
author_rank: Super Contributor
timestamp: December 20, 2024, 11:00:16 pm
content: Quote from: Zero999 on December 20, 2024, 10:48:32 pmThere 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 at3am.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.

author: coppice
author_rank: Super Contributor
timestamp: December 20, 2024, 11:12:56 pm
content: 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.

author: tggzzz
author_rank: Super Contributor
timestamp: December 21, 2024, 12:18:52 am
content: Quote from: coppice on December 20, 2024, 11:12:56 pmI really liked the MSDOS version. People who were usingMentalMentor 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.

author: Psi
author_rank: Super Contributor
timestamp: December 21, 2024, 06:11:32 am
content: Quote from: Analog Kid on December 20, 2024, 09:28:42 pmWe 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.

author: coppice
author_rank: Super Contributor
timestamp: December 21, 2024, 03:22:13 pm
content: Quote from: Analog Kid on December 20, 2024, 09:28:42 pmI 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.

author: jmelson
author_rank: Super Contributor
timestamp: December 21, 2024, 06:36:15 pm
content: Quote from: coppice on December 20, 2024, 11:12:56 pmUGH, 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