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how to make a simple Theft alert door alarm, using DC Motor Subscribe! California Gov. Gavin Newsom sues Fox News for $787 ...

When placed against a door on the floor, this nifty security device will blare a loud alarm if someone attempts to open the door. 15.99 13% OFF $ 13.99 at Amazon ...

The alarm station needs to stay plugged in, but there's a backup battery that lasts about 8 hours in case of a power outage. This Wi-Fi Door Alarm System is available on Amazon for $59.99. Blink ...

Eufy’s five-piece alarm kit serves as an introduction to a brand that also sells a wide range of additional smart security products. These include indoor and outdoor cameras, a more powerful hub ...

This article was originally published with the title “ Detonating Door and Window Alarm ” in Scientific American Magazine Vol. 8 No. 8 (November 1852), p. 60 doi:10.1038 ...