Looking for first-time advice on setting up an LED strip with light sensor/timer

Hey guys!

I've seen some amazing and awesome things online done with the Arduino, and I was hoping to give it a try! Sorry if this seems like a really excessive project for a beginner; I've been looking for an excuse to buy an Arduino and I've come up with the perfect excuse! Hopefully someone can help me out.

I have a saltwater fish tank which I recently got a new fancy LED light fixture for. The fixture is great, however it doesn't have an option to dim the LEDs throughout the day. Fish and coral can really benefit from having an accurate day/night cycle, and I'm hoping to simulate this in the tank.

One way people do this is add "moon-lighting", which is basically a series of blue actinic LEDs that give a nice blue glowing effect. What I'm hoping to do is have a series of these LEDs that are controlled by the Arduino (18" LED strip I was thinking of found here http://www.ebay.com/itm/Aquarium-440-nm-Actinic-BLUE-Moon-Light-LED-Strip-100-Lumens-Ft-Salt-Water-Reef-/280905559007?pt=LH_DefaultDomain_0&var=&hash=item416746abdf). Even though I could slap the LED strip on a standard plug-in timer and call it a day, I would much rather do something awesome and learn from it!

The light fixture itself is currently on a timer. My idea is to have the blue LEDs turn on as the lights turn off, using a light sensor hooked up to the Arduino. Then program a specific time for the LEDs to turn off. In the morning, I'd like to have a specific time to have the LEDs turn on, then have the light sensor turn them off when it registers the light from the fixture. Hopefully that makes sense!

I've got some good knowledge of computers and soldering, but unfortunately none about programming. I'd love to learn a lot from this project! I'm also not really sure what I would need for this project (at all). If someone could point me towards the model of Arduino as well as the components I should be looking at, I would really appreciate it!

Again, sorry about my newness to all of this. Hopefully this project will help me break my way into the world of Arduino! Thanks for reading!

You know, Your fish tank moon light simulation could easily be done with a tiny solar panel and a PNP transistor but that would operate at 100% brightness during night then shut off during the day, If you want dimming, see this http://arduino.cc/en/Tutorial/Fade

You can setup a clock on arduino and throw the light sensor out of the window

Also, The UNO would be very well fitted for this little project.

That sounds awesome, thanks for your quick reply! Is there any particular package or type of the Uno you would recommend? And also, where could I find the proper solar panel that would work with the Arduino? Any good sources to check out to find out where to get started? Sorry again about the questions; super eager to learn!

You may have not understood me correctly :stuck_out_tongue:

PNP transistors are always conductive unless a current is applied to their gate, Then they stop conducting, Imagine a solar panel outside, Outputting 5~ volts into the transistor's gate, That would close it until the sun goes away, Then the pnp transistor would conduct again, This solution does not have dimming and does not require arduino, It is also the most cost effective in my opinion

But again, You can ditch mother nature and setup a clock on the arduino, You would sync the clock to your country's time, Now say for example, The sun leaves at 7 PM, You can set it so that every time the clock counts to 7 PM, It keeps the LEDs lit till.. For example 6 AM, That would not require no solar panels, You can also implement dimming in whatever way you want, Arduino is the tool, The sky is the limit
Just get UNO R3, http://arduino.cc/en/Main/ArduinoBoardUno
It's as cheap as dirt and is very functional :slight_smile:

(Keep water away from arduino, Arduino never took swimming classes :wink: )


Perhaphs one advantage of the Arduino solution over a solar panel or other daylight detector might be that you could simulate the day/night cycle in the part of the world where the fish live in the wild, as opposed to the cycle where you live. I'm not a fish expert, I don't know if that is important.

Smaller and potentially cheaper than Uno would be Nano 3, Pro Micro or Pro Mini (for Pro Mini you need a usb serial adaptor). All have similar capability to Uno but are more suited to breadboards for prototyping, rather than shields.


A simple ldr which you can mount in the closest window, then you simply amplify the conditions outside and they will fade when going dark outside…

But, I think the best solution is simply to buy a real time clock ic, so you know the time then provide the correct amount of light from the correct part of the world…

These led strips are not that energy intensive, so you could use an npn rated for a couple of amps and pwm to fade the strips in and out…