Hello everyone! I currently have 6 feet of LED's that I'd like to run through my Arduino UNO. I understand that I will need an alternate power source, but I was hoping to look for a diagram and the parts I will need in order to do this? If I am no mistaken, this will only need one pin? Thanks everyone!
Hi and welcome.
It all depends...
What's important is not so much the length of the led string (although that can become a factor with longer strings) but how many leds, the specification of those leds and how they are wired.
Did you/will you make the string or buy it? Give us links to the products.
The number of pins needed depends on the type of leds and what you want to be able to do with them. Colour control, individual control etc.
Paul
PaulRB:
Hi and welcome.It all depends...
What's important is not so much the length of the led string (although that can become a factor with longer strings) but how many leds, the specification of those leds and how they are wired.
Did you/will you make the string or buy it? Give us links to the products.
The number of pins needed depends on the type of leds and what you want to be able to do with them. Colour control, individual control etc.
Paul
Thanks! You guys are all very friendly and patient here!
I purchased some LED's similar to these:
I just need to be able to make them flash when instructed by the Arduino! The LED's are all I have right now.
Thanks!
OK, so those leds need a 12V supply. You can run the Arduino off that same supply because its barrel connector (assuming you get an Uno) can take that voltage. This supply needs to be regulated, or switch-mode. If you have what you think might be a suitable supply because it says 12V on it, use a multimeter to measure the voltage of it's output when there is nothing else connected. If it measures 12V, fine. An unregulated supply will measure considerably higher, e.g. 15~20V when no "load" is connected.
Next think about current. The eBay page has almost no useful information, and this is typical of many eBay vendors. Is seems to say there are 15 leds on a 12" strip, which seems to indicate there would be 90 in a 6' strip. That seems an unusual number, they generally come in 30 or 60 leds per metre. You had better count the leds on your strip. The eBay page also says nothing about the current requirements. 20mA per led is usually a good guess. This would make it around 1.8A in total, so look for at least a 2A supply. The Arduino's power requirements will probably be only around 50mA.
To switch the current you need a transistor. (You could do it with a relay, but they click and wear out and don't allow you to fade the strip.) I would recommend a power-FET (Field Effect Transistor) with a Logic-Level Gate, in a TO-220 style package. The most common type is probably IRL520 which looks like this
There are other models available. The IRL520 has max voltage of 100V and max current of 10A, so plenty for what you need, and it has that important logic-level-gate which means it can be controlled directly by an Arduino output. It would be a good idea to put a 10K resistor between the gate and the 5V output from the Arduino, to stop the transistor getting hot in the couple of seconds it takes for the Arduino to boot.