star grounds? - Page 1
Forum section: electronics / general

author: Rx7man
author_rank: Regular Contributor
timestamp: July 03, 2019, 07:14:44 pm
content: I was wondering how to make star grounds in Eagle 7...probably on a similar note, I find myself sometimes wanting to have a different name for a net without putting something like a 0 ohm resistor inthanks

author: capt bullshot
author_rank: Super Contributor
timestamp: July 03, 2019, 07:29:42 pm
content: No idea if there's a way to achieve this in Eagle 7, but the general method would be to place a fake 0R resistor to connect two different nets, and short this resistor out in the layout when everything else is done (will create a DRC error).Edit: I remember someone created a special component to achieve this - just two (or n) different pins in the schematic symbol, but shorted by solid copper in the componentpackagefootprint.

author: Rx7man
author_rank: Regular Contributor
timestamp: July 03, 2019, 08:24:17 pm
content: Yeah, I that's what I've been doing but was hoping there was a less kludgy way of going about it... I've been using a cutable trace since it doesn't take much physical space

author: cvanc
author_rank: Frequent Contributor
timestamp: July 04, 2019, 12:00:43 pm
content: Well, you can get one of these made. A physical star ground component. I found it inside an old Sony piece. Never saw anything like it before.

author: Jeroen3
author_rank: Super Contributor
timestamp: July 04, 2019, 01:00:50 pm
content: You can draw a component that has a few SMD pads that link together with a bit of copper layer.It might toss some DRC warnings, but you can make a star ground go to one point with different net names.

author: Sylvi
author_rank: Regular Contributor
timestamp: August 01, 2019, 05:59:03 pm
content: HiA star ground is a specific physical connection form so it has to be forced in the layout editor. Eagle wants to tie things in the same net with the shortest ath - as the flywire fliesWhen you grab a flywire, you just make a sweeping trace to move the starting point to where you want it to be, then lay the trace, then go back and rip up the sweeping trace. In analogue layouts we have to do this all the time so that grounding and power feeds will be correct instead of how Eagle defaults to shortest path. Remember, Eagle was designed for laying out digital circuits in the 1980s, and that is more forgiving than analogue.In the schematic, you can stylise it to show that x number of leads tie to a specific ground - maybe there are several stars that need to be separated? Personally, I never use the GND symbol and often begin laying stuff out before the schematic is complete. This lets me control how the connections flow without so many flywires to grab by mistake.

author: Rx7man
author_rank: Regular Contributor
timestamp: August 01, 2019, 07:42:59 pm
content: I don't know if there's a way to do it, but if you could have a device with only 1 pad but 2 net connections, that could do it.. .Maybe you could make it have 2 pads overlaid? (might cause problems connecting though, along with DRC rule violations)

author: ogden
author_rank: Super Contributor
timestamp: August 01, 2019, 07:52:03 pm
content: This do not answer question, just illustrate. Literally star groundPicture from Sony 1000$ HDD audio playermarketing.

author: ebastler
author_rank: Super Contributor
timestamp: August 01, 2019, 08:27:50 pm
content: Quote from: ogden on August 01, 2019, 07:52:03 pmThat's a surprising solution. Why would they implement it like that, rather than tie the grounds together in the PCB layout? Just a marketing gimmick to show off that they know about star grounding?!

author: ogden
author_rank: Super Contributor
timestamp: August 01, 2019, 08:45:40 pm
content: Quote from: ebastler on August 01, 2019, 08:27:50 pmYes, that copper star technically does not make sense. I believe it is marketing gimmick indeed, audiophoolery. - To show "no compromise design", justify price tag. Notice "audio" electrolytic capacitors as well (right upper corner of the pic)

author: Rx7man
author_rank: Regular Contributor
timestamp: August 02, 2019, 01:15:38 am
content: really love the "No Compromise" "ETC" label on the one ground leg