schematic rats nest - Page 1
Forum section: electronics / general

author: AlfBaz
author_rank: Super Contributor
timestamp: March 04, 2015, 11:56:56 pm
content: I'm trying to reverse engineering a relatively simple PCB but with a lot of discrete components.Has anybody seen aschematiceditor that can show rats-nest?Ideally the same as rats-nest on a pcb editor but for schematic. The idea is to lay out the symbols on a schematic in the same orientation as on the PCB then wire it all up as per the pcb. Once complete, export the netlist, delete wiring, import the netlist and have a ratsnest on the schematic allowing you to place symbols in a circuit readable manner then draw the wiring according to the ratnest connections, pretty much the same as you do in PCB layout

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 05, 2015, 12:45:47 am
content: I don't know offhand of too many schematic packages that support loading a netlist as schematic. Oddly, Multisim is one. It does a terrible job on automatic placement, but it does do it.Probably better off doing it by hand... unless the point was, your circuit is large enough that you're inevitably going to be making mistakes and want to avoid that. In which case... good question.Tim

author: AlfBaz
author_rank: Super Contributor
timestamp: March 05, 2015, 01:04:25 am
content: Quote from: T3sl4co1l on March 05, 2015, 12:45:47 amI'll have a look at it.Just to be perfectly clear, I'm not interested in automatic anything. I create, what is in essence, a schematic spaghetti, with symbols, connections, designators etc... Then I want to delete the wiring, leaving live dynamic rat's nest lines to be able to re-organise the symbols into a circuit that makes sense, using rat's nest lines as a guide.The process I'm looking for is so similar to PCB layout that I'm considering making bullshit footprints that look like schematic components, using the pcb layout tool as a pseudo schematic editor

author: T3sl4co1l
author_rank: Super Contributor
timestamp: March 05, 2015, 03:27:06 am
content: Multisim doesn't draw a ratsnest, but rather it seems like connectivity is a more fundamental concept to them than graphical objects. So it autoroutes the lines on dragging, at least by default. Not quite what you're expecting, but probably close enough?What's the end goal? It's possible to do reasonable work in Multisim/Ultiboard, but it hardly seems mainstream. Making "nice" schematics is tedious, and still requires post-processing. It's not exportable (or importable) by much of anything, as far as I know.Tim

author: AlfBaz
author_rank: Super Contributor
timestamp: March 06, 2015, 05:19:07 am
content: Quote from: AlfBaz on March 05, 2015, 01:04:25 amWell, so far, so good.Had to make a few adjustment to my brain with the constant reminder that this is NOT a PCB...Turned on "ignore obstacle", turned off online DRC to be able to cross tracks without hassle. No "Auto junction" so using a "toplayer" pad where there should be junctions. Custom ground symbols with a "ground" footprint for the PCB-Schematic etc...All in all it seems to be working quite well.When I'm happy with PCB-Schematic I can then rearrange the actual schematic sheet, checking for stuff ups with "Update PCB", without actually updating. Not much point in this latter exercise though, as I don't want to reproduce the cct.