I mostly use FETs. Although that has gotten to be more of a pain since the SD5400 went on boutique pricing. You take one for the action and the
2nd on the same die to servo out the temp stuff at DC.More esoteric is the use of mixers (the DBM kind) as attenuators. Provokes expressions of disgust in design review. Well, not when you are da boss I guess.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Advanced Circuits always includes a bag of microwave popcorn...
charlie
Darn, I never got that from them :-)
But they were always good to us and on time, that's what really matters.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
You guys must be buying crummy product.
Nah, they did a great job. And the trail mix was really good.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
A *complete* design history down to the placement of each wire sounds excessive. But what the heck, disks are cheap these days.
The next logical step would be to log every key and mouse click, and videotape everything that happens in Engineering.
John
Maybe K. meant "crumby"? ;-) Why would I name a pet salamander "Tiny"?
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Homonym shomonym.
Orwell ...
But seriously, all they want is that you are able to show, for example, why you dismissed a direct conversions scheme somewhere, how the old schematic looked, and how the new one looks. An answer like "Oh, ahm, well, I guess we must have purged the old files" raises some flags and creates an urge to dig some more.
They don't want to know the shoe size of all the people signing an ECO. At least not yet :-)
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
The ECOs I'm talking about are just "differences" files that PADS makes whenever you edit a schematic and want to carry the changes over to the PCB. We can do several of them a day when a board is being created or revised. At the end, we crosscheck the schematic and pcb netlists and formally release the new letter rev. We always archive all the released files of all the revs, and anything else that controls the configuration or processing of anything shippable.
We do formally release "real" ECOs.
But so far, we answer to nobody as regards internal procedures. What you buy is what you get.
John
That appears to be a sound procedure. As long as some prose is kept alongside so you don't have to wonder in front of an inspector "Now why did we change that?".
Can't do that in many of my fields because they are heavily regulated. Aero (stuff that will actually be flown for decades) and medical have their strict rules. In fact, I know of one large medical device manufacturer where the FDA put the padlocks on the doors. Very embarrassing. Luckily not a client :-)
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
What do you do with "what if" branches off a work in progress? What does Joerg do?
Joerg's process sounds like it's the "bury 'em in bullshit" answer to design documentation. ;-)
Inspector?
We keep a "next" file on a server, something like
J:\\NEXT\\V470\\AtoB.TXT
where anybody who has anything to say about rev A adds whatever they want to say. Production will comment on a pad or drill size. Purchasing will note any part EOL notices or whatever. Engineering might suggest a circuit change or a possible feature. Like that. Keeps us from forgetting the little stuff. We check any effective ECOs and the NEXT file whenever we do a board spin, before we decide what to actually do.
Everything on the servers gets archived regularly.
As far as I know, we have only one VME module flying, on a C130. Nobody bothered us about internal procedures. We have lots of stuff in test stands and deployable test sets, ditto.
Some people do sometimes request our quality procedure, so we send it to them.
John
I'm not sure what you mean by that.
John
You apparently save/rename on any small layout change (with Joerg taking the obsession to the schematic level). What do you do if you just want to see how something will work out, not necessarily with the intention of keeping the test? I often try things on a schematic (don't do layout myself) just to see how it'll work. I certainly am not going to do an ECO on every tweak. We're already beat up for the number of ECOs generated (stupid, but reality often is).
We do name and save every schematic change while we're working on a board layout. The one we're doing now is up to rev 35 or so, after maybe 2 weeks of layout.
I still don't follow the question. How would I "see if something will work"? Do you mean simulate? We don't simulate from PADS schematics. Actually, we don't simulate a lot at all, except FPGA logic and the occasional small subcircuit.
I often try things on a schematic
The kind of ECO I was discussing is just a PADS .ECO file, the way to communicate a schematic change from the schematic editor to the PCB program. Those are essentially scratch files. There's also an OLE mechanism for syncing the schematic and the board, but that's pretty much guaranteed to tie things into knots.
That PADS .ECO file is different from a real, formal Engineering Change Order document.
John
Yep. Sometimes also called auditors. And they do surprise audits. Knock, knock. "Good morning. I am Mr.So-and-so from the FDA and I would like to review your complaint database and some engineering items."
Sounds like a good method. I keep similar text files so nothing falls through the cracks. Also helps if a Dodge Ram hits me head-on and someone else would need to take over. No joke, this has happened. Not to me but the motorcycle of a client engineer in Europe decided to develop a crack in the frame at 100mph and then split into two parts. Sparks flying, leather suit, skin, muscle tissue and some bone chafed off. He survived but I had to take over for a while. This was only possible because he documented as much as I do.
Later he bought a Mercedes Diesel and quit riding motorcycles ...
But it's probably not something where the captain has to declare an emergency if it quits ;-)
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
You probably haven't worked in aerospace or medical :-)
Those are markets where the federales _tell_ you how it's done. You don't get to pick. And their requested methods make a lot of sense. If you violate that chances are they either put you out of business or you land in front of a jury some day. I've seen the FDA snuff out a huge business. It was not pretty.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
You do not have to generate an ECO for every little change, as long as nothing is produced with that change. As for obsession, this is the MO here: My last design has 16 consecutive SPICE files and three consecutive schematic files, of course along with three versions of the module spec. Now product was built, I am testing it right now.
16 might sound excessive but I can go back to every major design decision, look up the reasons and so on. It is very nice to be able to say "Oh, let's simulate this situation with the #5 file again where the other comparators were used". Of course I don't store when I simply try out another resistor value or transistor somewhere. Only after I decide to keep the changes. The SPICE files are under 50kB each and the schematics a few hundred kB. What's the big deal?And yeah, I am the kind of guy who starts every design with a blank word processor document.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
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