So, I'm planning a home automation system based around wireless nodes (MSP430G2553 plus NRF24L01+ module). Part of the motivation for doing this is that the wires carrying 24VAC between the furnace in the basement and the thermostat 2 floors up have broken and it's a terrible pain to fish new wires in a 100 year old house with knob and tube wiring inside the walls.
The PCBs for the nodes are on the way from Elecrow, giving me an opportunity to experiment with the radio modules and start on some other bits and pieces. Here is a simple relay box that will be used to switch the 24VAC line to the furnace contactor. It uses a double coil latching relay bought for some long-forgotten project and is powered by a 8.5 VAC doorbell transformer. The doorbell wires run conveniently adjacent to the furnace control lines in the basement.
I made a hideous mess of soldering to the perfboard, having both omitted to breadboard the circuit and misread the relay datasheet. The saving grace was using 2x turned pin DIP8 sockets to mount the relay. These little project boxes from Rapid are very handy, but slightly too small for this job. They will be perfect for the wireless nodes though. I am hoping the aluminium lids will made great ground planes for the dipole aerials JPN told us about.
