The need for the a Chicken water heater arose last winter when we were going away during some really cold weather. Going away for a couple of days in warmer w
eather is not problem as the food and water will last at least 4 days, however in the winter there is always a risk that the water will freeze leaving the poor things wit
h nothing to drink. The solution was to use a 40W light bulb to provide just enough heat to keep the water above freezing. Last year I just ran the power back to the house and manually turned it on an off as needed.
For this year I wanted to automatet
he whole thing, initially I was just planning to use a Pic but my design consultant ‘suggested’ I use a Rpi and base it on a safe 12V supply.
The heat source was easy a two 22W car brake lamps, the rest took a bit longer…
Part 2 – Interfacing to the Rpi
Having looked at the available interface boards I decided the world needed a really simple analogue interface / control board for the Rpi. A bit of development later the IOpi was born, offering the two 8bit analogue inputs and two volt free digital outputs. All controlled directly from the GPIO. no special serial interface drivers needed just your basic RPi.GPIO. – to see if there is interest in commercialising the IOpi I plan to run a Kick-Starter early in the new year
The prototype IOpi can be seen mounted on top of the Rpi, in the middle are a pair of higher power relays for controlling the power to the lamps with a 12-5v home brew PSU on the right.
The great thing about using an Rpi rather than my original Pic based plan is that I could sit comfortably in the house and develop [play with] the Python code.
Part 3 – The 12 V PSU
The downside of going for 12V is that I needed a quite chunky
DC supply, looking on Ebay I discovered that the work of LED ceiling lights has created a market for really good value 12V switch-mode PSUs, less that £15 later I had an 8A 12V supply.
Part 4 – The SoftwareTo be continued