Schematic preferences
in [Design]
|
Prev: Oil sources Was: Re: Would magn. pole reversal actually mess up electronic equipment?
Next: Oil sources Was: Re: Would magn. pole reversal actually messup electronic equipment?
From: krw on 19 Jan 2010 20:28 On Tue, 19 Jan 2010 17:02:27 -0800, "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote: >"krw" <krw(a)att.bizzzzzzzzzzz> wrote in message >news:cckcl59viig97bhnjl1mfmqnuefbblf0ch(a)4ax.com... >> Our shields mount on solder balls. The balls are shown in the corner >> with a billion ground connections. > >One nice thing Pulsonix lets you do is to "multiply-instance" a component... >you can name, e.g., a mounting hole MH[1:6] and connect it to ground, and on >the layout -- poof! -- you get six grounded mounting holes. How do you define "MH" and it's connections? >ORCAD of course doesn't do this, having almost zero significant new >development performed in something like a decade now. Certainly they have. They've developed a *lot* of new crashes.
From: MooseFET on 19 Jan 2010 20:48 On Jan 19, 10:47 am, D Yuniskis <not.going.to...(a)seen.com> wrote: > MooseFET wrote: > > On Jan 19, 12:29 am, D Yuniskis <not.going.to...(a)seen.com> wrote: > >> John Larkin wrote: > >>> On Mon, 18 Jan 2010 18:39:06 -0800 (PST), MooseFET > >>> <kensm...(a)rahul.net> wrote: > >>>> The reference of a part encodes the page it is on. R307 is on page 3 > >>> Yikes! Production would lynch us. After the layout is done, we > >>> resequence the reference designators in physical and numeric order and > >>> back-annotate the schematic. > >> Ditto. The problem I find with EDA tools is they don't let you > >> put "tags" in text on the sheets. E.g., if you have a note: > >> "D1 - D4 installed on heatsink" and you backannotate the > >> schematic, D1 may no longer be D1, etc. So, you have to manually > >> go through and update the notes. It would be nice if you could > >> set up cross reference tags like in DTP tools... > > > For issues like that: > > Put "NOTE 1" next to the parts on the heat sink with a dashed outline > > Then make NOTE 1 say "These parts are on the heat sink" > > Understood. In this case, it would have been too cramped to > put notes next to the sixteen components involved. So, I > opted for "Diodes installed on heatsink" below the bridges. > Or, "Required for Type A application" next to one group of > components and "Required for Type B application" next to > another. > > I.e., you learn how your tools are going to screw you and > adopt your documentation style accordingly! ;-) Yes, after the schematic is all done, it is converted to a DWG for the production folks. The conversion process sometime does stuff like changing the font size. I try to keep my text well spaced out.
From: MooseFET on 19 Jan 2010 20:54 On Jan 19, 8:30 am, John Larkin <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > On Tue, 19 Jan 2010 06:20:27 -0800 (PST), MooseFET > > > > <kensm...(a)rahul.net> wrote: > >On Jan 18, 7:02 pm, John Larkin > ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: > >> On Mon, 18 Jan 2010 18:39:06 -0800 (PST), MooseFET > > >> <kensm...(a)rahul.net> wrote: > >> >The reference of a part encodes the page it is on. R307 is on page 3 > > >> Yikes! Production would lynch us. After the layout is done, we > >> resequence the reference designators in physical and numeric order and > >> back-annotate the schematic. > > >We haven't done that since the 1980s. The technicians were the ones > >that > >suggested the change. We used to do boards with things like RA12 > >meaning > >column A row 12. > > We sometimes did that for classic arrays of TTL cans. > > One division of GE just used a number for the designator; 94 might be > a resistor, 95 a capacitor. > > The opposite extreme is amateurs that make up prefixes... TR for > transistor, RV for pot (RV actually designates a Recreational > Vehicle), LED for LED even! > > Most annoying, especially when combined with the dreadful 2K7 notation > and the accompanying bad circuits. I don't mind the 2K7 notation so much as using a 2.7K 5% in a place where the design really needed a 1% part. I have seen cases where the design only worked because most of the 5% resistors fall inside the 2% range. If they all happen to land jelly side down, the circuit fails. Way back when TR was the ref for a transistor on a lot of schematics. It wasn't standardized. There was also a symbol that looked like this: --- ! ! ! ! ------!>! !----- ! ! ! ! --- ! ! That is a PNP transistor > > John
From: MooseFET on 19 Jan 2010 21:15 On Jan 19, 4:50 pm, krw <k...(a)att.bizzzzzzzzzzz> wrote: [... schematics ...] > >> work fine. > > >Dots have lead to errors. If the reproduction of the schematic is > >less than perfect a mere fly spec can send the technician down a > >blind alley. > > I think that's more of an issue with hand-drawn schematics. I haven't > seen any problems (other than the damned software gets carried away > with dots) with CAD packages. I often have to support things in remote sites. The schematic is in the manual and may be some what degraded. > > >[... ground symbols ...] > > >What do you use for chassis ground? > > Pitchfork in the ground. > > >> is a digital grounds. I know, they analog and digital grounds > >> _should_ be the same. They will be soon. ;-) > > >You mean you don't flaot all your logic on the +5V plane? > > No, it hangs from it. ;-) > > > > > ------ > > -----! 7805 !--------+--------- Logic Vcc > > ------ > > ! > > +----------------------- Logic grounds > > ! > > /---/ 5.1V > > ! > > +----------------------- HC4051 Vee connections > > GND > > >I really did do this and the technicians didn't even kill me > >for it. I avoided adding a switching device to make a minus > >supply for the Vee and the minus swings. > > >> >Mounting holes are shown if they have electrical meaning. > > >> Shields? > > >Shields are soldered to "mounting holes" and schematically show > >as a dashed line running through the hole and around the area. > > Our shields mount on solder balls. The balls are shown in the corner > with a billion ground connections. I don't believe the components > under the shield are shown (I agree, they should be).
From: Tim Williams on 19 Jan 2010 22:01
"krw" <krw(a)att.bizzzzzzzzzzz> wrote in message news:ammcl51ru610geu3nnh3e9l4c0a10e6114(a)4ax.com... > Visio also allows you to leave a break for crossings; much nicer than > speed bumps. Both speed bumps and gaps are programmable. > > | | > -------------------------- -------------+--------- > | | I always draw a vertical gap. I think it looks better than a solid cross, but not as hollow as a horizontal gap, which seems like there's more missing. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms |