On Tue, 13 Mar 2018 14:38:35 -0700, Joerg <news@analogconsultants.com> wrote:>On 2018-03-13 08:43, John Larkin wrote: >> On Mon, 12 Mar 2018 17:43:07 -0700 (PDT), whit3rd <whit3rd@gmail.com> >> wrote: >> >>> On Sunday, March 11, 2018 at 1:59:26 PM UTC-7, John Larkin wrote: >>> >>>> The original justification was that decimal points were somehow >>>> fragile and got lost on drawings, so the wrong parts values got >>>> installed. It was nonsense of course. >>> >>> Too young to recall thermal fax machines? >>> Lines that crossed got rather fat at the intersection, >>> and the images faded over time. >> >> I started with hand-drawn schematics on vellum, and blueprint >> machines. And I still use both. And I never lose or mistake decimal >> points or tie points. Maybe that's because I had two semisters of >> engineering drawing in college. >> >> I don't think that a D-size schematic could be FAXd, then or now. >> >> A lot of current "wisdom" is left over from olden days, and especially >> bad, amateur habits of olden days. We have computers now. Parts lists >> are generated automatically from our schematics, and computers don't >> mistake decimal points for coffee stains. Software gets the net lists >> right even when two wires cross. >> > >I have found bugs in netlists. Mostly where wires looked like they >connected to a component but didn't. I check every schematic on all my >designs against the netlist by hand. Doing one right now. It's tedious >grunt work but better safe that sorry.Some bad schematic software, like OrCad, allowed one to miss a connection by a single pixel, and get an open circuit. LT Spice can do things like that. PADS does not allow a wire to terminate into free space; every wire end must terminate connected to a part pin, or a big fat dot to another wire. It's impossible to create an open end or a free-floating wire segment. I don't manually check PCB netlists for connectivity; it's never wrong. I do sometimes read a netlist to make sure I haven't mis-named nets, like CLOCK12 on one sheet and CLK12 on another.> >On the last one I found a bug that was my fault. The eye sight isn't >getting better and I thought one node was connected to -12V where in >reality it was +12V. Going through the netlist that jumped right at me >... whew. > >Down to my last crayon pencil now. It is still from my old 1st grade kit >and I thought they'd last until retirement. A new set of 12 is en route >from China, $1.87 free ship, couldn't believe it. That should last me >for netlist checks until I am 120.Just yesterday Mo gave me a new box of Crayola colored pencils. I love colored pencils. She sure knows how to make a boy happy.> > >> Scientific notation and SI units are correct. The 4K7 thing is amateur >> audio nonsense. >> > >It was worse in the old days. Often a schematic said .001 with no units >whatsoever and you had to guess from the function of the circuit what >that meant. Not a problem for us seasoned guys but that could throw >freshly minted engineers a curve.-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Dot allowed as characters allowed in netlist?
Started by ●March 11, 2018
Reply by ●March 13, 20182018-03-13
Reply by ●March 13, 20182018-03-13
On Tue, 13 Mar 2018 15:11:04 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>Den tirsdag den 13. marts 2018 kl. 22.38.37 UTC+1 skrev Joerg: >> On 2018-03-13 08:43, John Larkin wrote: >> > On Mon, 12 Mar 2018 17:43:07 -0700 (PDT), whit3rd <whit3rd@gmail.com> >> > wrote: >> > >> >> On Sunday, March 11, 2018 at 1:59:26 PM UTC-7, John Larkin wrote: >> >> >> >>> The original justification was that decimal points were somehow >> >>> fragile and got lost on drawings, so the wrong parts values got >> >>> installed. It was nonsense of course. >> >> >> >> Too young to recall thermal fax machines? >> >> Lines that crossed got rather fat at the intersection, >> >> and the images faded over time. >> > >> > I started with hand-drawn schematics on vellum, and blueprint >> > machines. And I still use both. And I never lose or mistake decimal >> > points or tie points. Maybe that's because I had two semisters of >> > engineering drawing in college. >> > >> > I don't think that a D-size schematic could be FAXd, then or now. >> > >> > A lot of current "wisdom" is left over from olden days, and especially >> > bad, amateur habits of olden days. We have computers now. Parts lists >> > are generated automatically from our schematics, and computers don't >> > mistake decimal points for coffee stains. Software gets the net lists >> > right even when two wires cross. >> > >> >> I have found bugs in netlists. Mostly where wires looked like they >> connected to a component but didn't. I check every schematic on all my >> designs against the netlist by hand. Doing one right now. It's tedious >> grunt work but better safe that sorry. > >missing connections to a component should be caught by ERCHow does that work? -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●March 13, 20182018-03-13
"Joerg" <news@analogconsultants.com> wrote in message news:fgqtppFfk28U3@mid.individual.net...> Not in the schematics but in module specs I do because those are also read > by non-EEs. It has sometimes resulted in engineers asking me how I got the > Omega symbol in there since it's not on a US keyboard. No kidding. > > I was sometimes tempted to respond that I imported a keyboard from Greece > for that :-)Ah, that's another good bugaboo, Unicode compatibility. That's something Altium's been dragging on for over a decade (finally fixed in AD18). In these long-since-WinXP days it seems so ordinary to have Unicode support. Yet so many programs screw it up so badly. Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: https://www.seventransistorlabs.com/
Reply by ●March 13, 20182018-03-13
On Tue, 13 Mar 2018 22:38:57 +0100, Gerhard Hoffmann <gerhard@hoffmann-hochfrequenz.de> wrote:>Am 13.03.2018 um 22:20 schrieb Joerg: > >> It's worse. LTSpice cannot distinguish between milli and mega if you use >> m and M. It'll always see that as milli. You have to write MEG or e6, >> else it'll go wrong. > >That is the correct behavior. Changing that would break old decks >that used to work for 40 years. > >Gerhard029 keypunch machines didn't have lowercase. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●March 13, 20182018-03-13
On Tue, 13 Mar 2018 13:24:45 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>Den mandag den 12. marts 2018 kl. 01.05.11 UTC+1 skrev John Larkin: >> On Sun, 11 Mar 2018 16:31:40 -0700 (PDT), Lasse Langwadt Christensen >> <langwadt@fonz.dk> wrote: >> >> >Den mandag den 12. marts 2018 kl. 00.24.44 UTC+1 skrev John Larkin: >> >> On Sun, 11 Mar 2018 15:47:45 -0700 (PDT), Lasse Langwadt Christensen >> >> <langwadt@fonz.dk> wrote: >> >> >> >> >Den s�ndag den 11. marts 2018 kl. 23.27.16 UTC+1 skrev Jeroen Belleman: >> >> >> On 11/03/18 18:08, John Larkin wrote: >> >> >> > On Sun, 11 Mar 2018 09:37:59 -0700, Joerg <news@analogconsultants.com> >> >> >> > wrote: >> >> >> > >> >> >> >> Sorry for the occasional non-political post ... >> >> >> >> >> >> >> >> In the past I have seen special character issues with netlists across >> >> >> >> foreign country boundaries. For example, in some countries they use a >> >> >> >> comma as the decimal "point" and NXP also has those dreaded "...,215" in >> >> >> >> some part numbers. That can blow a netlist out of the water. >> >> >> >> >> >> >> >> How about a real decimal point (a dot) inside a footprint? >> >> >> >> >> >> >> >> Main reason I ask is for mounting hole designators. A client wants all >> >> >> >> this in metric dimensions and that will require fractions of a >> >> >> >> millimeter. For clarity I'd like to list that as "4.5MM_DRILL" footprint >> >> >> >> or similar. If dots are not allowed I could only use 4500UM_DRILL" or >> >> >> >> such and that's less understandable. >> >> >> > >> >> >> > We delete extra characters in our parts database. TO247, not TO-247. >> >> >> > But decimal points are necesssary. We haven't seen any problems with >> >> >> > that, but we rarely send BOMs outside the company. >> >> >> > >> >> >> > You could adapt the dreaded 4K7 convention: 4MM5drill. >> >> >> > >> >> >> > >> >> >> >> >> >> Oh, that would be a 4m5 drill. A 4M5 drill would be something to >> >> >> behold! >> >> >> >> >> > >> >> >m is the SI unit for meter soo, >> >> > >> >> >https://3.imimg.com/data3/GP/EO/MY-4706592/tunnel-boring-machine-500x500.jpg >> >> > >> >> > >> >> >> >> Since we have SI units, and accepted scientific notation, why do some >> >> people use the insane and ambiguous 6v8 style? That seems to be mostly >> >> amateurs and audio people. >> >> >> > >> >how is 6V8 ambiguous ? >> > >> > >> > >> >> That's just ugly. But how would you do 6850 volts? >> >> 6v85K 6kv85 6k85v ? >> >> Does r mean ohms, or decimal point? >> >> 0r5 could be next to a resistor, or an inductor. > >I believe engineering format for 0.5 would be 500m > >do you put ?/F/H after every component value? > > >On a schematic, we'll show 15nF or 12uH. We show resistors as 10m or 0.5R or 22.5R or 15.3K or 499K or 10M or 2G. Actually, each part on a schematic is defined by an HTI attribute which is our company stock number. A 49.9K 0805 1% resistor is stock number 132-6671, which is what appears on the BOM and controls what manufacturing actually puts on a board. The VALUE attribute "49.9K" is essentially a comment. I did write a little PowerBasic program that checks the visible values on a schematic against the parts database to make sure they agree. There's a lot more to a part than its value. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●March 13, 20182018-03-13
On 2018-03-13 15:36, John Larkin wrote:> On Tue, 13 Mar 2018 22:38:57 +0100, Gerhard Hoffmann > <gerhard@hoffmann-hochfrequenz.de> wrote: > >> Am 13.03.2018 um 22:20 schrieb Joerg: >> >>> It's worse. LTSpice cannot distinguish between milli and mega if you use >>> m and M. It'll always see that as milli. You have to write MEG or e6, >>> else it'll go wrong. >> >> That is the correct behavior. Changing that would break old decks >> that used to work for 40 years. >> >> Gerhard > > 029 keypunch machines didn't have lowercase. >:-)) Almost spilled my glass of water here ... But yeah, got to keep the old stuff humming. We still fly DC-3's in the US, profitably. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 13, 20182018-03-13
On 2018-03-13 15:11, Lasse Langwadt Christensen wrote:> Den tirsdag den 13. marts 2018 kl. 22.38.37 UTC+1 skrev Joerg: >> On 2018-03-13 08:43, John Larkin wrote: >>> On Mon, 12 Mar 2018 17:43:07 -0700 (PDT), whit3rd <whit3rd@gmail.com> >>> wrote: >>> >>>> On Sunday, March 11, 2018 at 1:59:26 PM UTC-7, John Larkin wrote: >>>> >>>>> The original justification was that decimal points were somehow >>>>> fragile and got lost on drawings, so the wrong parts values got >>>>> installed. It was nonsense of course. >>>> >>>> Too young to recall thermal fax machines? >>>> Lines that crossed got rather fat at the intersection, >>>> and the images faded over time. >>> >>> I started with hand-drawn schematics on vellum, and blueprint >>> machines. And I still use both. And I never lose or mistake decimal >>> points or tie points. Maybe that's because I had two semisters of >>> engineering drawing in college. >>> >>> I don't think that a D-size schematic could be FAXd, then or now. >>> >>> A lot of current "wisdom" is left over from olden days, and especially >>> bad, amateur habits of olden days. We have computers now. Parts lists >>> are generated automatically from our schematics, and computers don't >>> mistake decimal points for coffee stains. Software gets the net lists >>> right even when two wires cross. >>> >> >> I have found bugs in netlists. Mostly where wires looked like they >> connected to a component but didn't. I check every schematic on all my >> designs against the netlist by hand. Doing one right now. It's tedious >> grunt work but better safe that sorry. > > missing connections to a component should be caught by ERC >Not if, for example, the pin is declared as output in the symbol because leaving outputs unconnected is perfectly ok. Same for I/O or passive.>> >> On the last one I found a bug that was my fault. The eye sight isn't >> getting better and I thought one node was connected to -12V where in >> reality it was +12V. Going through the netlist that jumped right at me >> ... whew. > > that is hard to catch, sorta a like spellchecker can't pick the right word > for you >Operator error is one of the reasons why I will always hand-check netlists after finishing a circuit design. Bugs in CAD systems are the other. Today's netlist went through sans error. Those color pencils really seem to be made only for kids. It says name, class and school on the box, in Chinese. -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 13, 20182018-03-13
On 2018-03-13 15:31, John Larkin wrote:> On Tue, 13 Mar 2018 14:38:35 -0700, Joerg <news@analogconsultants.com> > wrote: > >> On 2018-03-13 08:43, John Larkin wrote: >>> On Mon, 12 Mar 2018 17:43:07 -0700 (PDT), whit3rd <whit3rd@gmail.com> >>> wrote: >>> >>>> On Sunday, March 11, 2018 at 1:59:26 PM UTC-7, John Larkin wrote: >>>> >>>>> The original justification was that decimal points were somehow >>>>> fragile and got lost on drawings, so the wrong parts values got >>>>> installed. It was nonsense of course. >>>> >>>> Too young to recall thermal fax machines? >>>> Lines that crossed got rather fat at the intersection, >>>> and the images faded over time. >>> >>> I started with hand-drawn schematics on vellum, and blueprint >>> machines. And I still use both. And I never lose or mistake decimal >>> points or tie points. Maybe that's because I had two semisters of >>> engineering drawing in college. >>> >>> I don't think that a D-size schematic could be FAXd, then or now. >>> >>> A lot of current "wisdom" is left over from olden days, and especially >>> bad, amateur habits of olden days. We have computers now. Parts lists >>> are generated automatically from our schematics, and computers don't >>> mistake decimal points for coffee stains. Software gets the net lists >>> right even when two wires cross. >>> >> >> I have found bugs in netlists. Mostly where wires looked like they >> connected to a component but didn't. I check every schematic on all my >> designs against the netlist by hand. Doing one right now. It's tedious >> grunt work but better safe that sorry. > > Some bad schematic software, like OrCad, allowed one to miss a > connection by a single pixel, and get an open circuit. LT Spice can do > things like that. PADS does not allow a wire to terminate into free > space; every wire end must terminate connected to a part pin, or a big > fat dot to another wire. It's impossible to create an open end or a > free-floating wire segment. >That's how it should be. Even Eagle misses that at times so the drill is to move all the parts at the end and see if everything rubber-bands along. Other than that it is fairly good though I won't make the transition to the new owner's "license tax model".> I don't manually check PCB netlists for connectivity; it's never > wrong. I do sometimes read a netlist to make sure I haven't mis-named > nets, like CLOCK12 on one sheet and CLK12 on another. >That's another error that can happen. Then there is the run of a wire into the wrong net and it got overlooked because the schematic is very busy. When tracing off the netlist in the schematic it's "Hey, wait a minute, why does this connect to the 7th line and not the 8th?".>> >> On the last one I found a bug that was my fault. The eye sight isn't >> getting better and I thought one node was connected to -12V where in >> reality it was +12V. Going through the netlist that jumped right at me >> ... whew. >> >> Down to my last crayon pencil now. It is still from my old 1st grade kit >> and I thought they'd last until retirement. A new set of 12 is en route >>from China, $1.87 free ship, couldn't believe it. That should last me >> for netlist checks until I am 120. > > Just yesterday Mo gave me a new box of Crayola colored pencils. I love > colored pencils. She sure knows how to make a boy happy. >I now have a brand new set of Miao Ke color pencils, with the colors probably blessed by the comrades from the local party committee.>> >> >>> Scientific notation and SI units are correct. The 4K7 thing is amateur >>> audio nonsense. >>> >> >> It was worse in the old days. Often a schematic said .001 with no units >> whatsoever and you had to guess from the function of the circuit what >> that meant. Not a problem for us seasoned guys but that could throw >> freshly minted engineers a curve. >[...] -- Regards, Joerg http://www.analogconsultants.com/
Reply by ●March 13, 20182018-03-13
On Tue, 13 Mar 2018 15:57:28 -0700, Joerg <news@analogconsultants.com> wrote:>On 2018-03-13 15:36, John Larkin wrote: >> On Tue, 13 Mar 2018 22:38:57 +0100, Gerhard Hoffmann >> <gerhard@hoffmann-hochfrequenz.de> wrote: >> >>> Am 13.03.2018 um 22:20 schrieb Joerg: >>> >>>> It's worse. LTSpice cannot distinguish between milli and mega if you use >>>> m and M. It'll always see that as milli. You have to write MEG or e6, >>>> else it'll go wrong. >>> >>> That is the correct behavior. Changing that would break old decks >>> that used to work for 40 years. >>> >>> Gerhard >> >> 029 keypunch machines didn't have lowercase. >> > >:-)) > >Almost spilled my glass of water here ... > >But yeah, got to keep the old stuff humming. We still fly DC-3's in the >US, profitably."Deck" means "punched card deck." Punch cards were a huge improvement over paper tape. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●March 13, 20182018-03-13
On 2018-03-13 15:54, John Larkin wrote:> On Tue, 13 Mar 2018 13:24:45 -0700 (PDT), Lasse Langwadt Christensen > <langwadt@fonz.dk> wrote: > >> Den mandag den 12. marts 2018 kl. 01.05.11 UTC+1 skrev John Larkin: >>> On Sun, 11 Mar 2018 16:31:40 -0700 (PDT), Lasse Langwadt Christensen >>> <langwadt@fonz.dk> wrote: >>> >>>> Den mandag den 12. marts 2018 kl. 00.24.44 UTC+1 skrev John Larkin: >>>>> On Sun, 11 Mar 2018 15:47:45 -0700 (PDT), Lasse Langwadt Christensen >>>>> <langwadt@fonz.dk> wrote: >>>>> >>>>>> Den s�ndag den 11. marts 2018 kl. 23.27.16 UTC+1 skrev Jeroen Belleman: >>>>>>> On 11/03/18 18:08, John Larkin wrote: >>>>>>>> On Sun, 11 Mar 2018 09:37:59 -0700, Joerg <news@analogconsultants.com> >>>>>>>> wrote: >>>>>>>> >>>>>>>>> Sorry for the occasional non-political post ... >>>>>>>>> >>>>>>>>> In the past I have seen special character issues with netlists across >>>>>>>>> foreign country boundaries. For example, in some countries they use a >>>>>>>>> comma as the decimal "point" and NXP also has those dreaded "...,215" in >>>>>>>>> some part numbers. That can blow a netlist out of the water. >>>>>>>>> >>>>>>>>> How about a real decimal point (a dot) inside a footprint? >>>>>>>>> >>>>>>>>> Main reason I ask is for mounting hole designators. A client wants all >>>>>>>>> this in metric dimensions and that will require fractions of a >>>>>>>>> millimeter. For clarity I'd like to list that as "4.5MM_DRILL" footprint >>>>>>>>> or similar. If dots are not allowed I could only use 4500UM_DRILL" or >>>>>>>>> such and that's less understandable. >>>>>>>> >>>>>>>> We delete extra characters in our parts database. TO247, not TO-247. >>>>>>>> But decimal points are necesssary. We haven't seen any problems with >>>>>>>> that, but we rarely send BOMs outside the company. >>>>>>>> >>>>>>>> You could adapt the dreaded 4K7 convention: 4MM5drill. >>>>>>>> >>>>>>>> >>>>>>> >>>>>>> Oh, that would be a 4m5 drill. A 4M5 drill would be something to >>>>>>> behold! >>>>>>> >>>>>> >>>>>> m is the SI unit for meter soo, >>>>>> >>>>>> https://3.imimg.com/data3/GP/EO/MY-4706592/tunnel-boring-machine-500x500.jpg >>>>>> >>>>>> >>>>> >>>>> Since we have SI units, and accepted scientific notation, why do some >>>>> people use the insane and ambiguous 6v8 style? That seems to be mostly >>>>> amateurs and audio people. >>>>> >>>> >>>> how is 6V8 ambiguous ? >>>> >>>> >>>> >>> >>> That's just ugly. But how would you do 6850 volts? >>> >>> 6v85K 6kv85 6k85v ? >>> >>> Does r mean ohms, or decimal point? >>> >>> 0r5 could be next to a resistor, or an inductor. >> >> I believe engineering format for 0.5 would be 500m >> >> do you put ?/F/H after every component value? >> >> >> > > On a schematic, we'll show 15nF or 12uH. >I use 15n and 12u, just like with resistors.> We show resistors as > > 10m or 0.5R or 22.5R or 15.3K or 499K or 10M or 2G. > > Actually, each part on a schematic is defined by an HTI attribute > which is our company stock number. A 49.9K 0805 1% resistor is stock > number 132-6671, which is what appears on the BOM and controls what > manufacturing actually puts on a board. The VALUE attribute "49.9K" is > essentially a comment.That is a very good strategy and should be done at all companies.> ... I did write a little PowerBasic program that > checks the visible values on a schematic against the parts database to > make sure they agree. > > There's a lot more to a part than its value. >Especially if it goes unobtanium. I just spent 3-1/4 hours to replace one lone part, inluding an online session with Texas to check the layout, just in time for prototype fab submission tonight. To make it extra fun a recent upgrade of LTSpice must have tossed out some symbols so several schematics error all the time. One I found and recreated, the other can't be found because it won't point out the location and everyhting is now there and simulates ok. -- Regards, Joerg http://www.analogconsultants.com/
