If this has a better place to be, feel free to move it. My Dad must sleep with pressurized oxygen, c-pap, and a sealed mask. Without it, he may stop breathing, permanently. His fear is that during a power failure, he might not wake to remove the mask. I put his fears to rest with this home built device. If you rely on power when you sleep, you are encouraged to copy this. (This is my design, and there is no patent. ) alarm is turned off by unplugging DC or restoring AC only. It can not be turned off by mistake. I started with a car alarm speaker. And cut down the bell to just insert into a 4" PVC scheadual 40 and sealed it in place, facing out. I cut a PVC soil cap (black and flat) to mount the AC outlet and power cords (one ac one 12vt DC with car jack) Mounted inside the tube is a 115vt relay that is wired to drop out when the AC fails to connect DC by default.(AC holds the circuit open). Plug the DC into any 12vt power source, (in this case, a large flashlight that is also available for use during the power failure). Plug in breathing equipment through the alarm. No DC power is used, unless alarm goes off. This alarm will wake the neighbors! It can be muted, by standing on end or adding a cap, but it will still wake you well beyond the abilities of any alarm clock. I added a side handle for ease of carry and packing, and to prevent rolling about. Cut tube length to minimum size needed, and slip on soil cap without glue. (This allows for repair or fuze replacement as needed)
