I have been working on an update to my Raspberry Pi Chicken Water Heater project recently, replacing the analogue temperature sensors with DS18B20 digital Temperature Sensors. At the same time I have simplified the heater relay circuit, replacing the interposing relays with opto-isolators. The final change has been to scrap the linear sub-regulator in favour of a switch mode device. The gap on board is for a Raspberry Pi battery backup circuit, I have been working on for a while.
To give it all a test before setting up outside I have set it up to monitor the turkey defrost, logging the temperatures and tweeting an update every hour ….