Hi, I am currently working on creating an automated LED-strip running on 12V, 2A DC. I am using a grove shield so I have two options to work with:

• The Grove Relay that outputs a 30V 1A DC / 10A 250V AC.
• Directly from a digital output. Giving me PWM option.

I am not very knowledgeable in electric circuits; any advice is appreciated.

The first already isn't an option because it can only handle 1A...

But what do you want to do? Only turn it on/off? Or do you need dimming? Is it indeed 2A of leds? And is it one group? etc You're a bit scarce with details...

This is the LED-strip: http://www.kjell.com/se/sortiment/el-verktyg/belysning/led-lister-led-tejp/flexibel-led-tejp/led-list-300-led-varmvit-5-m-p63899. I am thinking of a dimming function. The lable on the strip says 24W and 3,4 W/m on the page. I don't quite understand what you mean with one group?

With one group I mean do you want the whole strip to do the same or do you want to be able to control individual segments of the strip (cut it in pieces).

3,4W/m gives you 5m x 3,4W/m = 17W. 17W / 12V = 1,4A. That's to much for the 1A of the relay. I don't see the 24W you talk about.

And if you want to be able to dim the strip a relay isn't an option. Just use a logic level N-mosfet to drive the strip.

Alright, MOSFET is a bit out of my knowledgebase but I suppose I would be able to achieve the same with an OP-amp?

So if I understand you correct if the strip is short enought I could power it with just the relay? If i turned down the voltage ofc.

Could you elaborate another thing for me: to dim the light all I have to do is to change the output voltage?

but I suppose I would be able to achieve the same with an OP-amp?

No. An op amp can not delever the current output you need.

to dim the light all I have to do is to change the output voltage?

No you change the duty cycle of a PWM signal switching the LEDs. You can not dim with a relay. http://www.thebox.myzen.co.uk/Tutorial/PWM.html

MOSFET is a bit out of my knowledgebase

Then learn about them or forget this project.

What Mike says. Just google Arduino mosfet or Arduino ledstrip and be greeted with tons of info :) Driving a ledstrip from an Arduino is like the oldest trick in the book nowadays.

Alright, thanks very much guys!