I have a fish tank and in it - lives many tropical fish - however the other day the plug socket switch the heater was plugged into somehow got knocked off. luckily I noticed the heaters light wasn't on and the water temp hadn't dropped so the fish were safe however I wanted to make a little device to warn me if the mains got turned off somehow without having to wire it to the mains directly.
So here we have a little device that starts beeping if the mains is turned off - obviously this is battery powered but the battery should last a long time because it's very low current draw.
the trim pot on the board adjusts the sensitivity of the antenna which is just a piece of wire than you wrap around the cable you want to monitor.
