uln2803 ground?

[ingre_dients]

Hi, if I have a ULN2803A connected to an outside power source, do I need to have the ground go to the arduino as well? I've been using it this way and it works fine, but it occurred to me that it may not be needed. Or is it a good idea?

The voltage going through the ULN2803 is 13volts.

Thank you.

[franklin97355]

Yes, you need the grounds connected between all the devices you are using. That's how the signals get back to their respective components.

[ingre_dients]

Ok, so using 3 ULN2803s I should have all 3 grounds connect to the arduino ground and the ground of the 13V power supply? Could I connect all 3 grounds and arduino ground together, then have them all go to ground of the supply - - or does it not matter how they are connected. ie, all together is fine?

Thanks, I don't know much about this, so thanks a lot for your comments.

[ingre_dients]

Oh, I see now, you mean the 5 volts the pins are sending to the ULNs need to go back to the arduino.. of course. Sorry, that makes a lot of sense. But if they are all connected together, how does the arduino 5 volts know to go back to the arduino (and not the ground of the 13v) Sorry, another basic question.

[ingre_dients]

Excuse the barrage of questions, but the arduino has 3 grounds, does it matter if I connect all 3 ulns to one?

[adafruit_support_bill]

does it matter if I connect all 3 ulns to one?

Not a problem.

[ingre_dients]

and I can connect the ulns to the 13v ground as well - all together?

[adafruit_support_bill]

All of your grounds should be connected together.

[ingre_dients]

Thanks a lot, I thought so, I will do that. Glad we are on "common ground"

[ingre_dients]

Is there any difference between the 3 ground pins? Any would work?
Sorry if your last answer was referring to this already.

[adafruit_support_bill]

They are all interconnected by the ground-plane on the board.

[ingre_dients]

Ok, thanks a lot.

[philba]

spammer. got me once.

Edit on 8/25/2012: First off, this doesn't look like something I would say in response to the questions posed. You can look at my other postings to see that's not my style. It's been a really long time since that post but I seem to recall some actual spam that was posted to a number of threads. I believe the mods then removed the spamming user which caused their posts to go away, making for the situation we have here. Sorry if you felt that was aimed at you, I don't believe it was.

[ingre_dients]

Philba,

I'd really like you to explain why you called me a spammer.

What caused you to do this?

I am an artist and am not associated with any company. Do you think I was trying to sell my sculptures to you on the sly?

I find it very offensive and embarrassing that you would call me this on this public forum - without a shred of reasoning. If you want to make this forum into a place of 'insiders' and 'outsiders' well then you've done that. I didn't know what spammer meant for a long time, but it was enough to make me stay away from the forum for a long time - being very offended.

I would appreciate it if you would take back that false accusation. and explain how you could so irresponsibly post a label like that on me on this public forum.

I understand that spammers are a disgusting group of people and make us loose faith in each other. But unfounded horrible accusations are equally as bad - and cause just as much harm.

[adafruit]

ingre_dients

we do not believe philba was replying to your post, he/she could have been replying to a spammer post that was later removed. we'll follow up with philba over email and ask. we have a positive, supportive great community here

feel free to email us: support@adafruit.com

we'll update this post shortly too.

update: hey ingre_dients, check out the edited post - it's all good

thanks,
adafruit support, phil