Hello,
I am trying to find a light chase to connect three light boxes. The boxes are set up with LEDs and each has its own transformer. The client would like each light box to illuminate independently for seconds in sequence.
Which Arduino product would be suitable for this application?
Thanks!
If the boxes should not be tempered with or hacked, you should try the power switch tail and control each led box with one such switch. You can't dim the LEDs this way. It's only on/off. Any arduino such as UNO will work.
Using Arduino as a Light Chase
I am trying to find a light chase to connect three light boxes.
No problem! If you can [u]blink[/u] one LED you can blink 3 LEDs in sequence. And of course, you can control something else besides one LED per output.
The boxes are set up with LEDs and each has its own transformer.
If you are going to switch the AC power, you'll need a relay or a solid state relay (or the Power Tail liudr suggested) A relay allows you to control a high voltage & current with a lower voltage, and it provides electrical isolation between the Arduino (and you!) and the lethal voltages.
Solid state relays are easier to use than electro-mechanical relays, but they are more expensive. Get solid state relays that use 5V on the input-side and are rated to control AC voltage & current equal to or greater than your AC load.
If you get a regular electro-mechanical relay you'll probably need a relay driver circuit to boost the current & voltage to the relay coil and you may need to provide 12V for the relay coil. (You can buy relay boards with multiple relays and drivers installed.)
...But before you start, plug the light boxes into a switched power outlet and make sure the LEDs switch on & off quickly and "cleanly" without flickering or anything. Since there is a power supply you didn't build, you can't be sure how it will behave when switched rapidly.
Thanks for all the info! It is very helpful.
I can access the interior of the boxes and wired the LEDs together myself. I just want the lights to blink on and off they do not need to dim.
So it sounds like I can accomplish this with the Arduino Uno, but then I also need the relay - do I plug the relay into the power source, and then plug the Arduino into that, and then the light boxes to the Aurduino? Can I use one relay for all of them or does each light box need a relay? (that seems a little over complicated and expensive). Just trying to figure out the easiest way to make them blink at the desired interval 
Thanks again!
What LEDs do you plan to use?
Relays seem like a great fit for this application but depending on the LEDs there may be other options.
You will need some sort of switch (relay etc.) for each set of LEDs you want to control.
An Arduino can certainly do what you want but so could just about any microcontroller.
Do you want to be able to change the timing of the on and off events? If so what do you want to use as an input device?
I'm using a standard strip of bright white LEDs, each with their own transformer.
I want to set the timing for the lights to a specific interval but don't necessarily need to change it after that. This is the first time I've attempted this so I'm just looking for simplest and most cost effective solution - any advice is very welcome!!!
Thanks
" The boxes are set up with LEDs and each has its own transformer"
Its own transformer, means its own power? What power is needed to turn the box on/off?
If it is just a 5Volt signal, then the arduino can provide that voltage (without a relay).
LKlenow:
I'm using a standard strip of bright white LEDs,
There's no such thing as a "standard strip of bright white LEDs".
It would be good to know how much current the LEDs required.
I think the previously mentioned relays would work. Electromechanical relays will likely require a transistor, a resistor and a diode to interface with an Arduino. Electromechanical are less expensive than solid state relays (SSR). A SSR has several advantages. One is it doesn't require extra parts and can be driven directly by an Arduino. Another advantage of SSRs is they're quiet. SSR don't click when they're turned on and off. SSR often last longer (this has been my experience).
The downside to using SSR is the price. They're generally more expensive than the electromechanical kind.
To switch a AC load, you need to make sure and get a SSR made for AC. SSR are generally made for either AC or DC, not both.
It would be good to know how much current the LEDs will draw so an appropriate relay can be selected.
My guess is something like this relay would work.
You will need one for each group of LEDs you want to control individually.
Post some pictures of the inside of one box.
The LEDs that I'm using are 12v, bright white LED strips, each about 19" long.
I purchased an LED Magician thinking it would be simpler and not require so many additional parts. But the lights are still moving to fast.
Can I use the LED Magician as the relay and then use the Aurdino Uno to better control the lights so that they blink slower?
(The boxes are already installed in the store so unfortunately I don't have any images of them).