DIY Aquarium Monitor

I have just started building this DIY project to plug your aquarium into your PC and get it to monitor and turn things on and off. Hopefully it might give someone some ideas on what can be done fairly simply. My plan is to hook this up to my PC when I am away from home and get it to send me text messages to keep me informed of what is going on with my aquarium(s).

The ultimate goal of the project is to allow the system to monitor temperatures and trigger cooling devices, send txt msgs to me when it detects a problem, monitor water levels (and maybe trigger a "top off pump"), that kind of thing. It could be used to control heaters and lighting too but I'm not sure at the moment if that is something I particularly want it to control. Although I may try them just to see how it could be done. Of course it could be extended also to monitor PH and activate CO2 system etc but that will be a sub-project along the road. I was also thinking of trying to see if it would be cheap enough to build a "wave maker" for marine use that would work out more economical that buying one off the shelf which seem to be quite expensive.

So far I have purchased the build it youself USB card to hook up to the PC and a Digital thermometer which can have an external temperature probe connected and can be wired up to have a min and max temp level that can trigger the USB card. This is what I have been doing so far.

The bare circuit board front and back





The connectors and USB port added



All resistors added



Capacitors and chip mounts added



Transistors, diodes, variable resisters, LEDs and chips added



Soldering job on the back

Remarkably, it all worked when hooked up to the PC and the test rig program running and controlling the USB card.





I will be writing the main controlling software using Borland Delphi once all the components are wired up and working.

The next "mini" stage was to make the thermometer read from a probe as by default it reads the ambient room temp. This is obviously no good for the tank as I don't want to put the whole thing in the water.

This is the thermometer and probe pre-modification.



First off was to remove the built in thyrister which currently controls what temp it is reading (circled in red).



... and connect in the external probe (circled in red). Tested it just by holding the probe between my finger tips to make sure the temp rose. Worked perfectly. At some stage I will calibrate the probe using the inbuilt calibration variable resister (circled in green).



Sorry, Ran out of wire to continue any further at this stage