Electronics > Beginners
Modern way to specify values on schematics
Richard Crowley:
--- Quote from: robertbaruch on March 03, 2019, 07:12:18 pm ---Corollary to #2: I prefer to use the IEC symbol for resistors, which is a rectangle. The value goes inside the rectangle instead of next to the symbol.
--- End quote ---
The problem with that rectangle is that it is confusingly overloaded. If ONLY resistors used the rectangle, OK. But there appear to be half a dozen different components that use the same rectangle (or a slight variation). Maybe it is a resistor, but there are some places where maybe it is a fuse. Or an inductor, or ????
I grew up reading the schematics in Popular Electronics here in the US and that was always my reference for nice design.
Zero999:
--- Quote from: jpanhalt on March 05, 2019, 10:41:22 am ---Interesting how so many feel they are using the SI system, often called the metric system, but don't follow its rules.
Source: https://www.nist.gov/pml/weights-and-measures/writing-metric-units
Rule(Spacing):
"A space is used between the number and the symbol to which it refers. For example: 7 m, 31.4 kg, 37 °C."
--- End quote ---
Probably because it's a stupid rule.
There are also other stupid things such as kg for the base measurement of mass and µ, for micro, which isn't found in all fonts, but u is generally accepted because it's close enough.
level6:
--- Quote from: ebastler on March 05, 2019, 03:22:51 pm ---
--- Quote from: Wimberleytech on March 05, 2019, 01:37:34 pm ---NEVER USE FOUR-WAY CONNECTIONS. NEVER USE DOTS to indicate a connection.
--- End quote ---
I agree with the "no four-way junctions". But for three-way junctions, don't pretty much all CAD systems use dots to indicate junctions, and don't DIN, IEC etc. require them in schematics?
--- End quote ---
I also thought dots are required for junctions (not talking about 4 way junctions). Eagle adds them in by default when connecting nets.
Wimberleytech:
--- Quote from: level6 on March 05, 2019, 04:30:35 pm ---
--- Quote from: ebastler on March 05, 2019, 03:22:51 pm ---
--- Quote from: Wimberleytech on March 05, 2019, 01:37:34 pm ---NEVER USE FOUR-WAY CONNECTIONS. NEVER USE DOTS to indicate a connection.
--- End quote ---
I agree with the "no four-way junctions". But for three-way junctions, don't pretty much all CAD systems use dots to indicate junctions, and don't DIN, IEC etc. require them in schematics?
--- End quote ---
I also thought dots are required for junctions. Eagle adds them in by default when connecting nets.
--- End quote ---
As long as four-way connections are NOT allowed, then dots are redundant. I am ok with a redundant dot...a pacifier dot. CAD systems are self checking so they won't make errors confusing crossovers with connections. But drafted schematics are notorious for this problem. I have reviewed many thousands of schematics in journal papers and patents. I see this issue all the time. Been awhile since I drew a schematic in Cadence, but pretty sure that tool does not allow four-way connections. Cannot speak for Eagle.
kuon:
Thank you so much for all your insight.
I have switched to this system https://www.eevblog.com/forum/beginners/modern-way-to-specify-values-on-schematics/msg2238423/#msg2238423 . The arguments makes the most sense to me and I can understand it.
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