Remote door lock status indicator

This is a follow on from Hippo's "Key with lock status indicator" idea.

Ever gone to bed and then worried if you've locked the garage or the shed ? Did you lock the back door after you let your cat out to prowl around, crapping in other people's gardens, killing <SQUELCH ... end of anti-cat rant>.

What you need is a lock status inidcator system. Very similar to an existing wireless burglar alarm, next to each lock is a small transciever unit. A sensor (reed relay or microswitch) is fitted inside the striker plate of the lock. Whenever the bolt moves in or out of the striker plate, the transmitter sends an "open" or "closed" signal to the central monitoring unit. The CMU has individual LEDs for each lock, and a big coloured panel which shows green for "all secure" and red for "at least one door not locked". The CMU would for preference be installed next to the normal final exit door from the building to give the user status indication as they left. Intruder alarms will generally detect if a door is not closed, but won't detect if a door is not locked.

A remote reperater could be installed in a bedroom etc. for peace of mind during the hours of darkness.

The idea of a wireless system is that it would be very quick and easy to retrofit. A cabled system would no doubt be cheaper to make, but more expensive and disruptive to install, especially if monitoring outbuildings etc.

This is NOT an intruder alarm per se, although the functionality could be easily built into existing alarm designs.