BEST OVERALL: YoLink LoRa Smart Window Door Sensors. ↓ Jump to Review. BEST BANG FOR THE BUCK: GE Personal Security Window and Door Alarm. ↓ Jump to Review. UPGRADE PICK: Ring Alarm 5-Piece ...

Economical circuit of an electronic alarm, notifies you when your door or window is open, is presented here. This circuit wired around the Quad 2-input NAND Schmitt trigger IC 4093 (IC1) can be ...

Now, instead of having an alarm that sounds as soon as the door is open, ... Only in my case it’s not the cat leaving the front door open, but the kids. Report comment. Reply.

The alarm in Figure 1 detects an open refrigerator or freezer door by means of a magnetic proximity switch that’s available from Radio Shack as an intrusion-alarm-system component. The circuit allows ...

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 6% OFF $ 14.99 at Amazon ...

Each $80 device, used to open and close garage doors and control home security alarms and smart power plugs, employs the same easy-to-find universal password to communicate with Nexx servers.