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Need help alerting when car door is opened

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Grashopr

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My wife's vehicle is a high-profile SUV which has been broken into on multiple occasions. We have an alarm on it, and it has been armed, however the placement of the vehicle in relations to our bedroom makes it near impossible to hear when it's going off. I would like ideas on how to build a transmitter circuit that sends a steady signal to another circuit in our house that will operate a buzzer so that I can contact the police when the vehicle's doors are opened. If possible, I'd like it to only operate during certain periods of time (after 11p til 7 am). I am unsure whether using AM, FM or a form of RF signalling would be best, and I"m unsure exactly how to get the signal from the vehicle to the house (I do have an available attic area that is close to the vehicle that I can put any type of receiver antennae in. I have trolled these boards for a while now, and I enjoy reading (and building) some of the designs' I've seen here. However my wireless experience is very VERY little. Any help would be GREATLY appreciated.

The 'hopper
 

Klaus

New Member
Perhaps it might be easier to adapt some kind of remote control rather than trying to build transmitters / receivers from scratch?
Simple model RC controls or garage openers come to mind. These are not very expensive for somebody driving a SUV ;). It should not be hard to modify the switch on these to link into the car door switch circuit via a relay.
On the receiver end you need to wire in a switch to turn on your buzzer.
You'd have to figure out how to power this equipment reliably, and some means to arm the transmitter in the car as you turn on the car alarm.

Have fun doing that, the pox onto all car thieves :evil:
 

Grashopr

New Member
Thanks for the quick help guys, however....the only thing I saw that was remotely helpful on that site was the FM-Radio Controlled Anti-Car-Theft device. This circuit only tells you when the vehicle is being stolen (and I really dont see it's use, as this circuit doesn't tell you it's being stolen until it's a few hundred yards away !!....). I need some way to detect that the doors of the vehicle are opening and make it to where I can ring the doorbell of my house during a certain period of time (say 11p til 8a). I see this as a few different circuit 'zones'...one circuit to act as a timer and 'go high' during certain times of the day. Another circuit to 'go high' whenver the doors of the vehicle are opened (maybe run it off of hte interior light>?) and to stay 'high' for a period of, say, 2 minutes. When both of those are 'high', a third circuit that transmits a signal (up to a hundred yards, dont need to go far), and a 4th circuit to receive the signal and 'short' the doorbell (I could even get a new doorbell and run "2", modifying one for 'only' alarm work. The timing circuit and the door open circuit I'm sure I can do....it's the trans and receive circuits that I"m lost on. Please advise.

The 'hopper
 

Grashopr

New Member
Thanks for the Bump John.....anyone have any ideas at all? Even a part of the circuit? Laying the entire thing out isn't necessary, maybe just some more ideas (like the RC Car idea....I looked into it, but powering hte transmitter without extensivemodifications will require changing batteries often....need something that runs off of the car's battery supply and is 'hideable').

Thanks in Advance
The 'hopper
 

jem

Member
Hi:

Here is my suggestion:

1. Get yourself an RF remote control Tx/Rx pair. For example, check this out: https://www.qkits.com/serv/qkits/diy/pages/QK157.asp. If you wish, you can build your own for less by using their AM transmitter, but then you will have more work to do in the signal encoding/decoding section.

2. For the Tx side, you can power the circuit from the car interior light (as soon as the interior light turns on, the Tx turns on from the same power supply. Might want to use a voltage regulator for the Tx for when the car is running (lots of noise and spikes which can kill the Tx). You might then add a two minute timer (lots of 555 based circuitry floating around).

3. For the Rx (inside your house) simply use a cheap timer from WalMart (no, I do not own WalMart stock!) and simply set it to turn on between the hours you need. When it is ON, it then powers the Rx, which will then ring your doorbell or other alarm. When the timer is OFF, the Tx can transmit all it wants, but the RX will then not be reacting since it is powered off. That way you do not need to mess with Real Time Clocks etc.

Hope this helps
 
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