> I have a small problem with small parts in a small area on a small board > (so what else is new?). > > I have 4 parallel channels of a Quad Transimpedance Amplifier circuit, > which is very high gain and requires good isolation. The circuit is all > descrete analog components, mostly 0402, except for the S0-8 op-amps, > and is packaged quite densely with only .020" between components in the > tight spots, and no room for package outlines. The circuit is layed out > very nicely, and is electrically excellent, but unfortunately, there is > no room for designators. <snip> > Anyone out there got any useful ideas? > > JaMi Smith
To start off with, this could well be my last post (or else very nearly my last post) from this email address. I'm currently looking for another job (preferably in Sydney, Australia, where I am currently living), with my current job finishing this week (the usual circumstances for this era). But I have recently signed up to these forums from my home email address, so other members of these forums will continue to hear from me on an ongoing basis, but from a different email address. Now on to this thread. It is being wise after the event, and not necessarily the "best" way to do it, but if you want components R1_1, R1_2, R1_3, and R1_4 (say), then add component R1_1 to the PCB file, then append a "R1" string (on the Top Overlay layer) to this component (using the Menu item 'Tools/Convert/Add Selected Primitives to Component'; the component's primitives need to be in an unlocked state at the time), then create the R1_2, R1_3, and R1_4 components from copying the R1_1 component to the (Protel) clipboard and then pasting back into the PCB file, then re-annotating the pasted components as required. The additional "R1" string is part of each of these components, and will thus move with its component whenever that component is moved. (Moving the string *relative* to the component will require the component's primitives need to be in an unlocked state at the time though, but keep in mind that the global command feature can be used to unlock (or relock) the primitives of more than one component at a time.) All up though, a lot of extra work is called for, even if it is all planned in advance (to minimise the amount of extra work required). But short of creating a customised addon Process of some sort (for example, one which acts upon currently selected "free" strings so that these are automatically appended to appropriate components which are also currently selected), I am not sure of any other way of doing it, other than the suggestion made by others to use the component's Comment strings. Concerning the use of Comment strings, the Schematic drawings could still be implemented to display component values (e.g. 10k, 100nF, etc) for each component by using one of the 16 Part Fields for this purpose, and setting the corresponding string to be visible. The Part Type (field) (for each component) could then be used to hold the desired abbreviated Designator (e.g. "R1" for components R1_1, R1_2, etc), with the corresponding string set invisible (unless it was desired to keep this visible). When information was passed from the Schematic File(s) to the PCB file, the Comment string of each component would then acquire the desired abbreviated Designator for this, and any subsequent re-synchronisation between the Schematic file(s) and the PCB file would *not* result in these desired abbreviated Designators being lost or over-written for *any* of the components (in the PCB file). Some extra work called for with that method as well, but if planned in advance, the amount of extra work required could again be reduced (and probably substantially). If used, I would strongly recommend the addition of an annotation to the Schematic file(s), documenting the usage of this technique. Regards, Geoff Harland. ----------------------------- E-Mail Disclaimer The Information in this e-mail is confidential and may be legally privileged. It is intended solely for the addressee. Access to this e-mail by anyone else is unauthorised. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it, is prohibited and may be unlawful. Any opinions or advice contained in this e-mail are confidential and not for public display. * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * To post a message: mailto:[EMAIL PROTECTED] * * To leave this list visit: * http://www.techservinc.com/protelusers/leave.html * * Contact the list manager: * mailto:[EMAIL PROTECTED] * * Forum Guidelines Rules: * http://www.techservinc.com/protelusers/forumrules.html * * Browse or Search previous postings: * http://www.mail-archive.com/[email protected] * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
