I am looking for a low tech device to tel me if a door have be open?
Thanks in finance
Answers: Try e reverse wired silent alarm..
Close the door and jam a small piece of thread within it. Nobody notices the thread, and when you find back if the thread is not within but on the floor, you know the door's been open.
A low tech device that can't be reset is one the intruder doesn't know is there, such as a small piece of rag on the top of the door in a specific location, a human hackle stuck between the door and the frame with spit, at a specific location, a piece of quality newspaper trapped in the door on closing beside a tiny corner showing held by a fingernail edge.
Knowing where on earth it was and have it either soaring or low makes it smaller quantity detectable.
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