Electronic conventions I hate

[Sceadwian]

Regardless of personal opinions on the need or validity of the change, it is however is an SI unit so arguing about it is pointless in and of itself.

 

[carbonzit]

It sounds as if you're still trying to defend your position (that the unit called the Siemens was not formerly called the "mho'), when you are, in fact, wrong about this.

If that's what you are defending, then you're simply incorrect. If we're somehow misunderstanding what you're writing, that's another matter.

The point is simple: the unit that measures conductance (the reciprocal of resistance) was called the mho (ohm spelled backwards for those who may have missed it) for many decades. Then, some people on some scientific committee somewhere decided to rename it to the "Siemens". It's the same unit, only renamed.

So are you saying this isn't so? Or are you trying to make some other point?

 

[Sceadwian]

The point is that if you use SI units of conductance it's Siemens, what was used before is irrelevant as it's not standard now, anything else is a personal opinion and really irrelevant to what is currently considered standard. Was the change in terminology needed or required? No, and the unit may have stayed the same, whatever collection of people's that chose to call it the Siemens decided to honor a historically active scientist in the field of electrical and thermal systems (as well as telegraphy)

Get over it =)

 

[carbonzit]

The point is that if you use SI units of conductance it's Siemens, what was used before is irrelevant as it's not standard now, anything else is a personal opinion and really irrelevant to what is currently considered standard.

So basically you're saying "Get over it. Quitcherbellyachin'. Shaddup. Get with the program."

Was the change in terminology needed or required? No,

Replace that comma with a period, and that's exactly the point some of us were trying to make! The change was completely arbitrary, unnecessary, and had nothing whatever to do with SI units, neat powers-of-10 ordering or anything else.

[...] and the unit may have stayed the same

The unit DID stay exactly the same. 1/R.

 

[Sceadwian]

The unit DID stay exactly the same. 1/R.

No it did not, because the mho was never an SI unit. The siemens currently is. The term mho was a popular convention before then not a standard and the siemens existed before as an artifact based version of the existing SI non artifact based unit.

The reason we decided to call resistance ohm's is in fact based on the artifact based nature of the siemens unit at the time, it was redefined as the simple 1/R equation at the same conference which declared it as the SI standard. The reason I'm saying anything at all is because this is not about convention, or common use, it is about what is considered standard.

 

[carbonzit]

[...] and the siemens existed before as an artifact based version of the existing SI non artifact based unit.

????? If you can explain what that means in plain English, I'll pay you ten bucks and eat my hat.

 

[Sceadwian]

The siemens was originally a unit of resistance, and had a value slightly less than one ohm. It was based on a mercury standard, and unrelated to voltage or current which made calculations difficult. This contributed to the decision to make the ohm the standard unit of resistance in 1881.

https://www.tech-faq.com/siemens.html

In the 19th century, the Siemens’ unit or Siemens’ mercury unit was a unit of electrical resistance introduced in 1860 by Werner von Siemens himself.1 One Siemens’ unit is approximately 0.9534 ohm. The standard was defined as the resistance of a column of pure mercury 1 meter long with a cross sectional area of 1 square millimeter, at a temperature of 0°C. For everyday purposes, the standard was realized as a German silver wire 3.8 meters long and 0.9 millimeters in diameter.2

https://www.sizes.com/units/siemens.htm

 

[Reloadron]

Alas the poor Mho gone forever. Does it really matter. It was nice as Ohm spelled backwards is Mho, pretty simple. Really matters not because anyone should know the reciprocal of resistance is conductance and visa verse. Years ago when I learned Ohms Law I learned E was equal to I*R and now it is taught as V is equal to I*R. So what does it matter? As long as it is understood that the voltage is equal to the resistance multiplied by the current it really matters not. So does it really matter that Siemens are the unit of conductance verse Mhos? I learned things one way and they changed, the same holding true for current flow. The point is in reality and practical application it matters not. It becomes a game of semantics for those pedantic about naming conventions more than anything of value as to solving the equation. Granted just my take on it but I try to look at both sides as in before and now.

By the way, so about the Solar System. What's the deal with Pluto? Someone decided it was too small to qualify? I learned 9 planets. Suddenly after all those years and all those school test there are only 8 planets? Someone decided that Pluto (like the Mho) was out?

Just My Take and MY Opinion
Ron

 

[carbonzit]

Well, Ron, maybe you can take heart from something I found at one of the links that Sceadwian posted:

The previous unit for electrical conductance was called the mho, and it is still used today in some areas of electronics. The name mho is actually ohm written backwards, signifying the inverse relationship between conductance and resistance.

I wonder what areas of electronics those are? Maybe ones practiced by old geezers like some of us?

Perhaps we can't do anything about these matters, as such decisions are handed out from on high, and all us peons can do is follow them. But we don't have to like it. This thread, like it or not, is all about complaining about such matters. It's something a lot of us humans like to do. So sue us.

 

[Reloadron]

Well, Ron, maybe you can take heart from something I found at one of the links that Sceadwian posted:



I wonder what areas of electronics those are? Maybe ones practiced by old geezers like some of us?

Perhaps we can't do anything about these matters, as such decisions are handed out from on high, and all us peons can do is follow them. But we don't have to like it. This thread, like it or not, is all about complaining about such matters. It's something a lot of us humans like to do. So sue us.

Hey CZ how goes it?

Well quite simply I figure it this way. My educational years of electronics were during the late 50s and the 60s. I learned things in a set fashion and the way I learned it has put beanies and weenies on the table for almost 40 years. I survived 40 years with 2 ex wives and three kids. I was able to educate those kids all doing it the way I learned it.

Considering it began with vacuum tubes (or valves for my friends across the pond) matters not. I adapted to tubes, transistors, and into today. Today when I sit with old friends, many dating back over 50 years and we joke around I say "Electronics have been very, very, good to me", and smile. Back then they thought my ham radio **** was weird. So yeah, trons have been good to me.

Changes were bound to happen. When someone said 10 kc we knew it meant 10,000 cycles per second even though as was mentioned it did not define it to cycles per second. Thus KHz was born so Hertz could have his place in the scheme of things and be immortalized. OK, so it better defined it but did it really matter? Nope as I saw it as cycles per second the way I learned it so if you want to call it Hz for the simple mind, cool with me.

If I see a radio dial labeled in Kilo Cycles or Kilo Hertz really matters not to me. I know what is meant and interpret accordingly. The same is true of Ohms Law and other formulas. It matters not and that was the point of my post. That is why I said in my opinion.

Just My Take
Ron

 

[unclejed613]

Regarding that, the capacitor with the curved bottom should only be used for electrolytics:

**broken link removed**

is for non-electrolytics, and

**broken link removed**

should be reserved for electrolytic (i.e., polarized) capacitors.

the curved plate is also the rotor in variable caps, with the straight one the stator. since the stator is usually grounded, the "function" of the curved plate was adapted to fixed caps with the usually grounded outer foil denoted as the curved plate. with monolithic caps, it would make sense to have two straight plates, but back in the days of typeset books, a publisher usually had one or the other type of cap symbol in inventory, so that's what got printed.

the nXn format of component values was introduced in the 70's i think, and while it took a little getting used to, it is much better than trying to decypher a missing decimal point. the ddm or dddm format is just a numeric representation of the color code, so that's not difficult, and the dddm format tells me i'm looking at a 1% tolerance resistor, but it's best to use these particular formats on the components themselves, they get confusing on a schematic, but the nXn format is pretty clear. i really think there should be some way of telling a SMT component from a thru-hole on a schematic (at least in "mixed" boards), but that's because i'm an old fart and don't like searching a board for a component on a "mixed" board, only to discover it's on the solder side of the board where it's impossible to get a scope or meter probe in to it's leads while the unit is powered.

and yes, i also hate upside down ground symbols..... even worse are the use of a ground as well as power supply lines (usually all in the same schematic) where the grounds and power rails are all denoted with a single line crossing the end of the "wire" (i.e. like a T). some of the best ones were where each supply rail was denoted with different shapes or polygons at the end of the wire, which really made things easier to trace.

another one i love to hate is the new symbols for an ADC with the pointed side towards the input.... a simple box with ADC in it was fine

 

[unclejed613]

Alas the poor Mho gone forever. Does it really matter. It was nice as Ohm spelled backwards is Mho, pretty simple. Really matters not because anyone should know the reciprocal of resistance is conductance and visa verse. Years ago when I learned Ohms Law I learned E was equal to I*R and now it is taught as V is equal to I*R. So what does it matter? As long as it is understood that the voltage is equal to the resistance multiplied by the current it really matters not. So does it really matter that Siemens are the unit of conductance verse Mhos? I learned things one way and they changed, the same holding true for current flow. The point is in reality and practical application it matters not. It becomes a game of semantics for those pedantic about naming conventions more than anything of value as to solving the equation. Granted just my take on it but I try to look at both sides as in before and now.

By the way, so about the Solar System. What's the deal with Pluto? Someone decided it was too small to qualify? I learned 9 planets. Suddenly after all those years and all those school test there are only 8 planets? Someone decided that Pluto (like the Mho) was out?

Just My Take and MY Opinion
Ron

when i was in grade school we were taught Bernoulli's Law of the relation between pressure and velocity, now modern hydrodynamics has demoted it to Bernoulli's Principle....

 

[Sceadwian]

Might want to careful with that statement UncleJed, you can purchase non-polarized electrolytic capacitors. The symbol should refer to polarized/non-polarized only.

 

[DerStrom8]

Might want to careful with that statement UncleJed, you can purchase non-polarized electrolytic capacitors.

Hmm, that sounds familiar....

Keep in mind that not all electrolytic capacitors are polarized...

 

[unclejed613]

also, somebody mentioned "conventional current"... actual electron current flows from negative to positive. "conventional" current predated Edison's discovery of the vacuum diode, and assumes current flows from positive to negative. this was based on visual observations of lightning striking the ground from a positively charged cloud. what is invisible (and high speed photography didn't exist in the 1700's) is the discharge of electrons from the ground to the cloud just before the visible flash.

conventional current can be useful in explaining the behavior of transistors, and so it is still taught in that context. anybody who has worked with tubes knows which way the current actually flows.

 

[Sceadwian]

Sorry Derstrom, I sent an apology last night apparently it didn't post properly. UncleJed was not wrong it was carbonzits post that I meant to post in reference to. You're quote that

Keep in mind that not all electrolytic capacitors are polarized...

Was in what post number in this thread?

 

[Sceadwian]

unclejed; ask the same question of someone working with chemistry or more raw physics. Conventional current notation is seldom used, it becomes REALLY complex in ionized fluid situations (chemistry)

Whichever one you CHOSE to use, it can always be converted to the other.

 

[DerStrom8]

Sorry Derstrom, I sent an apology last night apparently it didn't post properly. UncleJed was not wrong it was carbonzits post that I meant to post in reference to. You're quote that

Keep in mind that not all electrolytic capacitors are polarized...

Was in what post number in this thread?

Hey, no worries

That quote is from post #21

 

[carbonzit]

OK, 7 years after the last reply here I'm giving this thread a bump.

I just want to report on the status of metrification in the US. Since I work in a hardware store I have a pretty good idea of how measurement units/systems apply to ordinary household usage here, and some idea of use in various trades and professions.

For the most part we are still decidedly not a metric country. Most things are still measured in inches and feet: lumber and other building materials, pipe, metal parts, etc.

Fasteners: we certainly have metric screws, bolts, etc. They're all sold as "specialty" items, in the little drawers; so far as I know, none of the packaged screws, etc., are metric. So you can buy either a 1/4"-20 bolt or an 8x1.00 metric screw.

Tools: the only metric tools we have are wrenches of various types--socket, combination (box/open-end) and Allen (hex)--and a few tape measures that show both inches and centimeters. (None of the rulers we sell are metric.)

Household items: the capacity of all kitchen stuff, etc., is in Imperial units (ounces, quarts, gallons), but also with the corresponding SI units. I've never heard anyone ask for a liter measuring cup.

When people are looking for Allen wrenches I usually advise them to get both inch and metric sets, as both are equally likely to be found out there. Cars (at least newer ones), bicycles, motorcycles, anything from Ikea, and much of what is bought online (TV mounts, furniture) all have metric fasteners. Older "domestic" stuff (cars, bikes), domestic plumbing fixtures, towel bars, etc., are in inches. (I have heard of some bikes that have both inch and metric screws, but fortunately haven't actually ever seen one.)

We don't sell any metric drill bits of any type. Most are in fractional inches (e.g., 2-1/8", the standard size bore for a door lock), or in thous (number and letter drills, 1-80/A-Z). All pipe dimensions are in inches, as are all electrical fittings (conduit, etc.).

There is one exception to drill bits, which are the 35mm bits used for installing so-called "Euro hinges" (Blum, etc.). But we don't actually have that: we'll sell you a 1-3/8" bit instead, which is virtually the same size. (Our supplier doesn't carry a 35mm bit in that line.)

There are some dimensionless items, notably Torx (6-splined or "star") screws and drivers, which use an arbitrary numbering system (T-6, T-10, T-25, etc.). I have no idea what exact size any of these things are (either the recesses in the screws or the screwdriver tips), and I don't think any of my customers do either (or care). I do know that it's a damn good fastener drive system, much less likely to strip than Philips.

So there you have it; it's a crazy mixed-up world. Somehow we manage to muddle through. From the looks of things we're not going to metrificate any time soon (well, except for the de facto metrification of automobiles).

Oh, and I still don't like boxes for resistors on schematics, although someone up in this thread pointed out how they can reduce clutter in dense drawings. Luckily I don't have to deal with that level of complexity!

 

[KeepItSimpleStupid]

I'm likely to come in and ask for a "metric adjustable wrench" just to be funny. There might actually be metric flat blade screwdrivers.

I like mm and I hate mm. My boss once said all numbers have to be between 1-100. 10 mA fits, but 60,000 Pascals doesn't cut it.
I can't visualize enclosure sizes yet either. e.g. 554mm.

I bought a few stainless thimbles or even 2 pc shaft collars. They have say 1.5" bore and use a metric Hex wrench.