Electronic conventions I hate

[carbonzit]

Hi Mr RB,

I guess you never have dug through 500 sheets of schematics of an entire building with all electric installation.

Mainly if safety switches come into play it's impossible to get them all onto a single sheet. Therefore those schematics are divided in fields of numbers and letters with the numbers for the X-axis and letters for the y-axis starting at the sheet zero position which is usually the left hand bottom corner.

Sometimes "off-page" connectors can't be avoided. I'm right now looking at a schematic in the ARRL Handbook that spans 3 page spreads, with many off-page connectors. However, they're very clearly labeled: the arrow on each connector contains the number of the page where the mating connector can be found, with the ID name of the connector also given. A very good way to handle this problem.

 

[CraigHB]

Interesting to see people defending Fahrenheit!

I think centrigrade would be a perfect scale if they just doubled it, freezing at zero, boiling water at 200. The main reason I like F is because, for example, you really can feel the difference between say 75 and 76 on your home's HVAC thermostat. You'd need 24.0 and 24.5 to do that with C. That's an extra period and digit.

 

[4pyros]

What is 1 tenth of a centigrade?

 

[JimB]

What is 1 tenth of a centigrade?

A milligrade ?

JimB

 

[crutschow]

Deleted

 

[KeepItSimpleStupid]

A ran into a schematic ONLY once and I forget what it was for, but i liked it. Sometimes lines will cloud up a schematic, so this particular schematic ended the wire with an arrow and if you followed the arrow, you would find the corresponding arrow.

Then there is always p5, D2 type of designations where X,Y coordinates (Blocks) are placed on every drawing.

 

[Mr RB]

I don't think it's totally weak. To display roughly the same resolution with a digital thermometer at room temperature requires 3 digits with Celsius and 2 digits with Fahrenheit. For consumer applications, such as home thermostats, that can be a significant cost factor.

OK, point taken. But then if you are valuing fine adjustment (as said previously), what is better, a digital thermostat that adjusts in 1'F steps or a digital Celcius thermostat adjusting in 0.1'C steps?

Or what about the relationship between 'C:watts? Surely that's worth a lot in electronics.

Re PSI and kPa, I like PSI. I think PSI beat kPa by a long margin as it is a really nice sized unit. Pacals are stupidly small and the kludge of using kiloPascals doesn't help that much. And Bar is just too big to be useful. Plus PSI is friendly to convert if you know a surface area to get the force acting on it.

...
I guess you never have dug through 500 sheets of schematics of an entire building with all electric installation.

Mainly if safety switches come into play it's impossible to get them all onto a single sheet. Therefore those schematics are divided in fields of numbers and letters with the numbers for the X-axis and letters for the y-axis starting at the sheet zero position which is usually the left hand bottom corner. ...

Actually I have been in that situation, but usually the schematics were done right, with all the wires brought to a connector to the next module at the edge of the page and a note saying which page the next module was, with modules logically laid out.

What I was whining about was the times it is done wrong, like there is just one number on one wire, (not sensible connector groups) and the matching number(s) could be anywhere. Making it even more annoying when (like I said) the complete schematic is only 5 chips on 1 page and they could have just joined the wires on the page. But putting numbers next to the IC pins to save drawing wires is a lazy annoying cop-out and leaves you searching for all possible matches for every number!

 

[atferrari]

What possible difference could it make (to you as a human bean, not as a pointy-headed scientist)

Do they exist really?

 

[hdc090360]

[BTW absolute zero is -273K (elvin)[/QUOTE]

Going to be pedantic here.

Absolute zero is 0 K (Kelvin)
Absolute zero is -273 degrees Celsius. (not sure how to put the little superscript circle in that stands for degrees)

One Kelvin equals one degree Celsius it is just the origin point that is different.

Having said that, I always use the American symbols for my schematics. Much easier to understand a logic diagram.

It is not much of a problem today but 30 years ago, a lot of the schematics I had to use were poor photocopies of poor photocopies. This meant that things like decimals points sometimes disappeared. 2K7 made a lot of sense to me.

I love SI units. If everyone was educated in their proper use the world would be a much simpler place. (And the Hubble telescope would not need a contact lens )

My pet peeve is not using capitilization correctly in these units.

m and M are not the same!


Duncan

 

[KeepItSimpleStupid]

Going to be pedantic here.

Absolute zero is 0 K (Kelvin)
Absolute zero is -273 degrees Celsius. (not sure how to put the little superscript circle in that stands for degrees)

Duncan

Since we're being picky, absolute zero isn't -273 degrees C, it's -273.15 deg. C. See: https://en.wikipedia.org/wiki/Absolute_zero

Absolute zero is 0 deg. Rankine.

 

[hdc090360]

Yeah, I knew it was something like that.

Just too lazy to look it up.

Duncan

 

[atferrari]

The ° symbol

In my keyboard I can type "º" by pressing the (lower case) leftmost key / uppermost row wich goes together with "ª" (upper case).

Contrary to many ASCII tables which list Alt176 for it I get "°" by typing Alt248.

In my case, born in a "metric" country, I have the feeling of inches, feet, yards, fathoms, long tons and pounds because as a seaman I was exposed to them forever.

The somewhat unusal short tons were of use only when loading bulk cargo in USA terminals.

Along the years, Farenheit, I used them only in tankers to calculate the weight of cargo.

New built vessels (say for the last 20 years) have their draft marks in meters. The same for depths in nautical charts albeit distances / speed still in nautical miles and knots.

But, as somebody said, it matters what are you used to.

If asked, I would say that I am 1,59 m tall, (yes, a short man, I know) and no idea of it in feet/inches. I should have to think and calculate it.

BTW, mili, micro, nano and pico, when I have to use them for calculations are good to say what power of ten I have to punch in my calculator. Not a problem at all, it never fails.

The only standard in the globe is that everyone feels that what he uses is THE standard.

Standards of steel rust anyone? That is fun.

 

[atferrari]

What is 1 tenth of a centigrade?

decigrade Celsius

 

[CraigHB]

m and M are not the same!

That's why you often see M represented as Meg. A good example of that is in LTSpice. If you use M, it will interpret it as "milli". You have to use Meg or meg to interpret "mega".

And I agree, if we Americans would just swtich to SI units, the world would be a simpler place.

 

[crutschow]

OK, point taken. But then if you are valuing fine adjustment (as said previously), what is better, a digital thermostat that adjusts in 1'F steps or a digital Celcius thermostat adjusting in 0.1'C steps?

Or what about the relationship between 'C:watts? Surely that's worth a lot in electronics.

Of course 0.1'C gives a finer adjustment but, it fails the Goldilocks' requirement, it's too much for a home thermostat. 1'F seems about the right resolution whereas 1'C is too coarse.

What has 'C to do with watts in electronics? One is power and the other is temperature. There's no direct relationship between them.

 

[4pyros]

What has 'C to do with watts in electronics?

Temp rise with power?

 

[crutschow]

Temp rise with power?

Obviously that occurs. But that's not unique to the temperature being measured in celsius which was the point of his statement.

 

[4pyros]

Heat sinks are rated by their thermal resistance (Rth) in °C/W.

 

[carbonzit]

Heat sinks are rated by their thermal resistance (Rth) in °C/W.

But there's still no relationship between °C and watts. It's just the temperature measurement system used. °F would work just as well.

 

[4pyros]

°F would work just as well.

Yes but it is not used.