The idea here is to build a system that will do various functions such as turn on and off lights, pumps, and various aquarium stuff depending on time of day, whether something is high or low or some type of internal or external event.
To do this, you need some sort of “smarts.” In my case, I selected an Arduino “Clone” to be those “smarts.”
Some people call the Arduino a computer, and some call it a controller while others refer to it as a PIC controller. I’ll let you decide what you it is, I’ll just use it and call it a computer from here on out. :)
I selected a model 2560 because of all the different I/O (Input/Output) options it has, as this project has many sensors it has to monitor along with 20 relays to control “things” with. Eighteen AC control relays and two DC control relays. (I certainly hope that’s enough! :) Since I am going to need to connect a bunch of ‘stuff’ to the computer, I bought what they call a “Sensor Shield” for the computer. This is a little circuit board that has all the I/O pins situated on the top of it and when it connects to the computer, it covers the entire top of the computer, thus the “shield” part.
The computer needs to know what time it is if it is going to turn on and off the aquarium lights. To do that I got the little DS-1302 real time clock accessory to wire up to it. Now it will know if it is morning, afternoon, evening or night time.
I decided on using 19 inch rack mount equipment for the aquarium electronics. The main reason for this was the simplicity of mounting and unmounting the gear should it be required. It also tucks nicely in the top right side of the aquarium cabinet as well. So, sense I am using rack gear, it simply made sense to also mount the computer in a rack mount case as well. To house the computer, I had some old Blonder Tongue ZDM-8 TV demodulators laying around that seemed just the right size to put the computer in. So I commissioned one for this purpose.When I opened the case, to my surprise, there was a cool little power supply with 5 volts, 12 volts and 33 volts already for me to use. I really don’t see any use for the 33 volts, but the 12 volt defiantly will be used and since the computer is a 5 volt model maybe I’ll find a use for the 5 volts from the case power supply as well.
One other cool thing that I discovered with the demodulator case was that it already had circuit board standoffs tapped and stamped right into the floor of the case. I also found that the front of the actual case was separate from the faceplate, making it easier to work on without garfing up the faceplate. A trip to my local Radio Shack produced a couple of nice five and a half by two and three quarter inch perfboard that sits perfectly in the case.