I became used to those. However, before boarding a helicopter in Scotland for a flight to a North Sea oil rig they asked me how many stones I weigh and that threw me a curve.
Yup. Unless you force people into the other system and it goes wrong:
-- Regards, Joerg http://www.analogconsultants.com/
It could
They seem to use it a lot:
Gets really weird when engineers do it for resistors but not for capacitors, and this is technically a Japanese company:
-- Regards, Joerg http://www.analogconsultants.com/
Well, yes, serious is one descriptor. Noteworthy, or memorable, or instructive are other applicable descriptors. The carefuil use of technical language would lose its appeal if not for such anecdotes, where someone got careless.
Gimli glider and Mars climate orbiter are wonderful stories, and at least as instructive as anything Aesop came up with.
A schematic is a lot more than a netlist. It's a picture of the system. The visual should show more than a spreadsheet of the pins.
Or schematics are D-sized but are rarely printed as D-sized. I print them on Tabloid (B-size) paper but just as reference. But it's not irrelevant at all.
Exactly.
What is annoying is when busses change names at different levels in a hierarchy.
In a flat schematic, connected things have the same names.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Den fredag den 16. marts 2018 kl. 01.06.55 UTC+1 skrev snipped-for-privacy@notreal.com:
and if it ends up looking like netlist anyway a text editor is a much more efficient editing tool
and I hope that I never will!
-- John Larkin Highland Technology, Inc lunatic fringe electronics
The designs of my earlier days all had to be hierarchical because they were for systems with 32 to 128 channels. I never changed the name of any bus at different levels. I believe one could have combined buses into "bus-buses" so you had a large bus containing three smaller buses but I never did that. It would have made the schematic set hard to understand for others.
Flat schematics can make studying a schematic set cumbersome once they go past a dozen pages and it's all heavily interconnected. On systems with dozen of very busy channels they are almost impossible. Back in the
80's an ultrasound system had boards in 3xDIN size but extra long with 32 or so channels per board so you had to have at least two hierarchy levels per board. I used hybrids and had three levels. Then there was another level above that for the system which could contain 10-15 such board, plus power supplies, mux boxes, ECG modules, user interfaces, cable harnesses, ports and so on.-- Regards, Joerg http://www.analogconsultants.com/
Buses for ASIC design, are usually mandatory. Pretty much any chip worth its salt, is 10,000s of wires. Everything in ASIC design is hierarchical, maybe
10 deep at least.Bus names may require to be be different down the hierarchy. A dac used more than once might be, say 8 bits named say, SEL
Several instances of that dac in a block might have bus names SELA to connect to a SEL, and SELB to connect to a SEL of another.
I agree, one should try and keep them the same where possible.
-- Kevin Aylward
[...]
In that case we came into the block schematic with SEL and split it up visibly there. Usually not necessary though because the instances had to all be called out on a particular sheet in the hierarchy and then everything remained SEL, leading into numerous blocks which were on sub-sheets one hierarchy level down.
We had to have everything audit-proof for med grade. If the auditor wouldn't understand a schematic he'd red-flag it. It didn't matter whether is was correct or not, it was only as correct as the auditor says it was. Like it usually is with traffic tickets.
Yep. Just like the data trail in the accounting department, the traceability data in and out of of production, and so on. In our case the agency hammer was always above. One major goof-up and the padlocks come out. Young engineers sometimes belittled this and scoffed. Until it happened to a large competitor of us.
-- Regards, Joerg http://www.analogconsultants.com/
How are reference designators handled on a PC board with a hierarchical schematic?
We just start with whatever the schematic program picks. After the board layout is mostly done, we resequence the PCB and back-annotate the schematic. So we then have R1 R2... R185 in a nice physical order, which production and test want. That reordering might sweep across channels.
We don't want long reference designators; they take up too much room.
We do sometimes silkscreen boxes around channels.
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
There will be, for example, 32 sub-sheets and the renumbering routine goes through those one by one. Except for hybrids back in the days which we logged as components but had a (locked) schematic page in there so reviewers and other engineers could understand the signal flow.
We used to do that in the old days but even in the late 80's our production folks said it no longer really mattered. They all had screens and PCs to look that up. We were early SMT adopters. In the last 30 years I have only done a small handful of T/H designs and only if the client insisted.
That's why we often did away with silk screen ref des'es all together.
That's what we did for hybrids. Mostly no room for that though.
-- Regards, Joerg http://www.analogconsultants.com/
However you configure it to.
PADS might be awful on this, I have no idea. Altium you can set how to construct physical designators from logical components and subsheets. Personally, I like to prepend channel index to component index, so R301 in channel 2 --> R2301. Only need one copy of the schematic that way, no flipping through a half dozen sheets to find the one completely random component you're looking for.
In my experience, production is more than happy to call a component "FNARKLE1". If that's what's in the file, that's what it's called, no more no less. Who cares if it's a resistor on an "L102" footprint? If it fits, and that's what the BOM says, then that's what it's called.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: https://www.seventransistorlabs.com/
That could get old in a 128-channel ultrasond system, R128301 :-)
Better not to try that in aerospace or med-tech.
-- Regards, Joerg http://www.analogconsultants.com/
No reason other than the libraries are actually text files and that the general solution is impossible to automate.
Ltspice XVII installs as a new application not as an upgrade to ltspice IV so you can easily have both installed.
-- This email has not been checked by half-arsed antivirus software
Why is this not possible to automate? All the updater routine has to do is preserve everything in there and add stuff, never overwrite stuff.
I am still on IV.
-- Regards, Joerg http://www.analogconsultants.com/
Proving my point -- underscores and dashes are hard to read and look ugly as sin.
Tim
-- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: https://www.seventransistorlabs.com/
If the user can be trusted not lave the library in a state where the updater can't figure out what to do then yeah. But this is the real world, and users f*ck stuff up and then bitch and moan.
If the file has been modified it can be very difficult to determine what changes are needed.
There exists software that does a reasonably good job of merging edits, but it's not pefrect, and I'm not aware of any that meets ltspice's price and licence constraints.
what I'm saying is that instaling XVII will do you no harm (except disk space used)
-- This email has not been checked by half-arsed antivirus software
On parts, 4n5F is the same as 4.5nF; 7M13Meg the same as 7.13Megs .. so .. why not 4MM5_DRILL?
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