LED light strip wiring

[Aphra]

Hi,

I am creating an interactive light sculpture with a one colour LED strip. The project for interfacing a RGB light strip is very informative however I do not know how to translate this to my one colour LED strip. I need help with my wiring.

1. Arduino uno board
2. 2x LED strips (cool white, 5m)
3. External power supply
4. I have a relay too (don't know if I need it?)
5. I also have a couple of drivers (don't know if I need them either?)

How do I connect my single colour LED strip safely to my arduino so that I can use it to control whether the lights are on or off? I feel that it is a good idea to run these off their own power supplies rather than that of the arduino so how does the circuit look? Do I need anything to protect my arduino (like my relay?)

Anyhow how does the wiring work as I only have -+ cables from my LED strips?

Do I need these drivers in the circuit or can I just drive using arduino? Do I need to use the relay somehow?

I would really appreciate some help! I'm quite stuck right now! please,

Thanks

[adafruit_support_bill]

We sell several different types of led strip. We can help you if you tell us which Adafruit product you purchased.

[Aphra]

it was this one https://www.adafruit.com/products/887

[adafruit_support_bill]

It is best to use a separate power supply. Do you just need On/Off control? Or do you need to dim them also?

For on/off control you can use the relay, or a MOSFET. The MOSFET is also capable of dimming the strip if you connect it to one of the PWM pins on the Arduino.
The first wiring diagram in the tutorial is the one to use. But you will have just one color instead of 3. Connect the '+' wire to 12v and the '-' wire to the MOSFET as in the diagram.

[Aphra]

Thanks, for your response, I think I understand a bit better now. I still have a couple of questions though:

1. If I am using an external power supply for my leds how do I calculate which sort I need? E.g. how many amps (can you suggest one thats suitable?)
2. How does the external power supply fit into the the circuit as seen in the diagram? My + from my power supply goes to my + on my leds but where does my - from my power supply go?
3. Do I not need a driver?
4. I actually do want to be able to dim my lights actually I want to be able to fade them in, how do i go about doing this? How does the circuit change?

Thanks so much for your help.

[adafruit_support_bill]

1. You will need approximately 1.2A per meter to drive them at full brightness. This would be a good choice to drive them.
2. The positive terminal goes to the '+' on the led strip. The negative terminal connects to the Arduino ground.
3. The MOSFET is your driver. The strip has the appropriate current limiting for a 12v supply built in.
4. To dim the strip, you just need to connect the MOSFET gate to one of the PWM pins (3, 5, 6, 9, 10, 11) as shown in the circuit diagram. Brightness is controlled in your code by calling "analogWrite()"

[robertsgg]

I'm working on a project similar to this. Could you give me the part number of a MOSFET that would be appropriate in this situation (driven directly from the Arduino)?
Thanks

[adafruit_support_bill]

Could you give me the part number of a MOSFET that would be appropriate in this situation (driven directly from the Arduino)?

These work nicely: https://www.adafruit.com/products/355

[Aphra]

Hi there,

Thanks so much for your response I have got my leds all hooked up now and they are working great!

Thankyou again,

Aphra