Simple wireless window-open detector

[Tim Streater]

We've got a couple or three windows that we've got a bad habit of opening, forgetting about, and then going out. I'm looking for a simple system consisting of a sensor on the offending windows, which transmits to a receiver I'd locate near the front door. (We've got another system, IR-based, for general security but it doesn't do the windows.)

On the receiver I just need a row of LEDs to indicate which window is open - nothing more fancy than that, no hooters, alarms, or anything else.

Any suggestions? I can't get google to provide anything sensible.

[Tim Watts]

Tricky. There are Z-Wave devices but I suspect you will not like the cost.

You're right in that there should be a very simple device that transmits a simple coded pulse every 10 minutes or so - but I am not aware of it.

[Tim Streater]

This ought to be a market opportunity, but the devices that show up on Amazon either seem to be things that hoot when you open the window (but describe themselves as wireless, f*ck knows why) or seem to be part of a bigger system.

[Dave Liquorice]

Does it *have* to wireless? Ordinary alarm reed switch and magnet, two wires back to the display unit, resistor, LED and only one battery. I have sneaky feeling that would have LED on = window closed so use green LEDs not RED. B-) Simples, reliables.

[Brian Gaff]

No not seen anything wireless I have to say. I'm sure something could be molished up out of bits though it might not look very pretty. Brian

[Brian Gaff]

The design spec could be a 555 timer which switches on the transmitter each on a slightly different frequency, for a while each few minutes, this could only come on or go off if the window is open.

No real need for a sophisticated system. However this also coule be achieved with some of the older radio control kits that used to be sold, which used pulse width modulation for the various controls as I recall. Bet its all digital now. The other source of coding could be some of the chips used in ir remote controls of course. However all of these require delving into the guts of how the things work, and although this info is around, it seems not to be on the web under easily searchable headings. Brian

[Brian Gaff]

Yes this has been done by me when i could see, but he did say wireless. The other issue here is that window cleaners tend to push them shut but of course cannot latch them so it may look closed but without the handle lock it is easy to just pull open with a small tool from the outside.

Brian

[Syd Rumpo]

You need to get into the habit of checking. A note on the door handle saying, "Have you checked the windows?" could help.

Cheers

[Capitol]

Consider a CCTV video sender. About £14 each. They output a video signal on any one of 4 channels, You will need a psu to drive them, and need to supply a 0,7V signal to drive the input. I haven't thought this through completely, so you might get away with the car versions, which are much cheaper but doesn't have channel select AIUI. Just a thought.

Another thought, wireless pir detectors.

[Tim Streater]

We keep saying that and we keep forgetting.

Seems a bit overblown :-)

pir? How would they help? I'm not interested in preventing scrote ingress with this, I just want a simple device I can check as we leave the house. If an LED is lit, it tells me which window I've left open, I go and shut it. Simples.

[Capitol]

They can detect an IR source led being present.

[Harry Bloomfield]

Brian Gaff a écrit :

If they are modern security DG units, with a handle to lock the window into the sides of the frame, the metal brackets that the locking tongues move into when locked, could be used. There is no circuit path between the metal brackets, unless the window is both closed, and locked.

The same methods can be used on most modern security doors, apart from it cannot detect whether the actual key has been turned to complete the locking process.

I cannot think of an obvious, easy way to make them wireless, but the window transmitter would need some power anyway. Much easier to use wires and telephone multi-pair might do or alarm multi- pair cable. No electronics involved, just a few green LED's in a box at the door - when all lit, all windows are closed and locked.

[spuorgelgoog]

A transistor or two in the circuit would provide a LED off = window closed.

Owain

[Harry Bloomfield]

A PIR would only be triggered by a change in what it was viewing. If a window were left open and an LED lit up, then there would be no noticeable change to trigger it.

[Harry Bloomfield]

[e-mail] a écrit :

LIT, via a closed circuit, is a better and more reliable indication. A row of lit green LED's proves all are closed. A row of un-lit LED's could mean - LED's have failed, the power has failed, the circuit has a break in it somewhere, which is the much more likely fault.

[Adrian Caspersz]

Not a row of LEDs, but how about Key finders?

There was the old whistle to find key chain thing

2 x Whistle Key Finder Flashing Beeping Remote Lost Keyfinder Locator

Ye could wire some one along side a magnet / reed switch to cut the sounder when window closed, so that on leaving the house ye could whistle.... nah, scrap that - individual unit discrimination would be poor and ye might annoy the neighbours.

So maybe this thing adapted, with no need to whistle.

5 in1 Anti-Lost Electronic Remote Wireless Key Locator Finder Receiver Alarm UK

[Andrew]

Multi-sensor attaches to any door or window and detects movement (of door or window).

[Syd Rumpo]

Good idea. Wireless doorbells might be better, with a reed switch in series with the battery connection, wired so the batteries are connected when the window's closed - fail safe. On the way out, press the bell pushes to hear if the windows are closed.

Cheers

[Harry Bloomfield]

He is not trying to detect movement, but rather open or closed window and presumably locked.

[Tim Streater]

Yes, except that locked doesn't matter. If I close the window that suffices, you can't (easily) jemmy a uPVC window. We made sure we got windows with all the security bolts etc that engage when the window is shut.