Hello all, This subject probably been addressed before, but darned if I can find it. Anyway, I have put together a wireless telemetry receiver consisting of an Uno and LCD connected to an APC220 wireless transceiver. Everything works great. Now, as phase 2, I want to set it up such that it runs on an AC transformer when utility power is available, and switches to battery backup when utility power fails. Additionally, I want it to be able to send a signal to the uno that will allow it to switch to a power-saver mode. I have researched mux chips, but am now more confused than ever. Is there a relatively painless way to accomplish this? Thanks in advance!