Roll your own pressure alarm brainstorm session

Something like this switch probably would work.
http://www.grainger.com/Grainger/DWYER- ... itch-4FTN9
Works from about 0.3 cm H2O to 4.0 cm H2O, enough to detect operation, won't blow apart until about 100 cm H2O, way beyond our machines (us blowing apart). $39 but there are probably cheaper ones on the market too.

-tim wrote:I can get cheap door alarms at the local $2 shop that could be hooked to switch with a lever arm to the bag that archangle suggested.

If you're talking about the battery powered stand alone burglar alarm stuff, that definitely has some possibilities. Some of them even have the "enter a code" function that could help for the "turn it off in your sleep" crowd. Plus remote keypads to make you actually get out of bed.

archangle wrote: Plus remote keypads to make you actually get out of bed.

I'll be watching and waiting for that one.

Washing machines have switches in them that detect when the water level is high enough in the tank. the hose that comes out of the switch is about the same size as an oxygen hoses.

As the tank fills with water the water starts to go up the tube, increasing the pressure and eventually shutting off power to the valve that lets the water in.

here is one: http://www.partselect.com/PS269790-GE-W ... Switch.htm

the screw on the bottom adjusts the pressure level for shut off IIRC. Also some of these have multiple levels of sensors (small medium and large loads).

run a wire from a battery to one end of the contacts on the switch, run a wire from the switch to a buzzer, and from the other terminal of the buzzer back to the battery. If adjusted correctly, it will sound when you hook it up but when the cpap kicks in it should be quiet.

Yes, this unit costs some money, however I bet you could find a dead washing machine to take apart on craigslist for free.

One concern I have with this approach is pulses of pressure. If you sneeze, cough, breath in quickly the pressure in the hose may take a negative spike. this could give you a split second alarm unless you figured out a way to buffer the changes. Maybe an empty sealed 5 gallon bucket with a hose going in and out or a coffee straw in the line to limit the flow.

Of course this could lead to your death and my being sued by your relatives.. So forget I said anything

you are at your own risk and I have not tried this. Personally if the cpap machine is not working, I snore and my wife wakes me up !