Keeping the Temperature under control...
One of the main things you need to consider is a way to keep their temperature constant. You also need to know what that temperature is. I've been keeping reptiles and amphibians since I was about 12 and have always been astounded how difficult it is to get digital temperature control with multiple cages. So my electronics and programming background came in very handy when I started the original project about 10 years ago to build a device to control the temperature in my cages. This original device consisted of a single chip microprocessor with a 2 X 16 Character LCD display and a numeric switch pad, with a single TRIAC output for controlling the temperature of one cage. That project was very successful and could be used in multiple cages only if the cages were similar sizes (their temperature parameters were therefore similar). In this way I could read the temperature of one cage and all the other cages would track it.
Recently though I decided that I needed to upgrade my reptile temperature control to multiple channels, in other words - multiple temperature sensors, multiple TRIAC channels for the heaters, and all independant of each other. I also wanted to move away from the single chip micro and replace it with a PC running a .NET C# application to do all the grunt work. Heres how I did it:
First, I drew the circuit in an electronics CAD system. Main reason for this was that I eventually wanted to produce printed circuit boards. Then I built a prototype. The prototype actually ended up being my "production" hardware, but anyway thats another story. I did change direction and components a few times during this process, as I figured out the best way to do it using common components. There was also a fair bit of experimentation with the best way to use the available pins of a standard parallel port.
What I ended up with was an easily built 8 channel device connecting to any parallel port of a PC, and a C# program to control it.
If you'd like to know more, send me an email or call me, or Enquire Online