Arduino Forum

Using Arduino => General Electronics => Topic started by: A4kash on Jan 06, 2013, 06:20 pm

Title: connecting two common ground on the breadboard to one on arduino?
Post by: A4kash on Jan 06, 2013, 06:20 pm
Since i am a newbie,i have a problem regarding joining two common ground on the board.In this case the first led is connected to ground and some pin no. but the 2nd and third led,their anodes are connected to the pin nos. on the arduino board but their cathode is just left on the ground rail on the breadboard.What i am confused is can we connect these two ground from 2nd and 3rd led with the 1st led?
Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: codlink on Jan 06, 2013, 07:53 pm
All grounds should be connected.
Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: larryd on Jan 06, 2013, 08:01 pm
To start with, draw a schematic diagram of the circuit you are talking about. This helps to visualize whats happening.

For review: http://www.kpsec.freeuk.com/components/led.htm (http://www.kpsec.freeuk.com/components/led.htm) &
http://www.kpsec.freeuk.com/symbol.htm (http://www.kpsec.freeuk.com/symbol.htm)


Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: Docedison on Jan 06, 2013, 08:46 pm
Great Links... Both good stuff.

Bob
Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: fungus on Jan 06, 2013, 10:15 pm

All grounds should be connected.


No, all grounds MUST be connected.
Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: codlink on Jan 07, 2013, 12:37 am

No, all grounds MUST be connected.


lol, true, but can think of instances where you shouldn't, but that's for another discussion.. 

Like Larry said, we need a schematic of your setup to help in more detail.
Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: A4kash on Jan 08, 2013, 01:36 am
here ground fromarduino is not connected with the grounds from two leds...
Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: larryd on Jan 08, 2013, 01:58 am
I am having some trouble understanding.
The cathodes of all the LEDS can share a common ground point on a breadboard.
Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: A4kash on Jan 08, 2013, 09:35 am
Even without connecting common ground it worked and i am wondering how this circuit worked!!!Having problem in it....
Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: fungus on Jan 08, 2013, 10:00 am

Even without connecting common ground it worked and i am wondering how this circuit worked!!!Having problem in it....


Grab a multimeter and you can measure the difference between the grounds. Maybe you got lucky and it wasn't enough difference to burn out your LEDs or Arduino.

But don't depend on it. One day the magic smoke WILL come out of your components if you don't use common ground.

Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: A4kash on Jan 08, 2013, 01:00 pm
And this one didn't even worked at all....
Title: Re: connecting two common ground on the breadboard to one on arduino?
Post by: A4kash on Jan 08, 2013, 01:07 pm
and this was the circuit....