A new idea?


Active Member
I was just trying to think of a cheap (of course!) and easy way (Of course again) to monitor when and who's car was home and away.

I have a motion sensor in my car that helps to know if it is home or away, but I wanted something a bit more accurate, as to if the car is leaving or arriving home, not just when motion was detected.

I had a bit of a revelation, and don't recall ever seeing an approach like this. So I figgured I would run it by a few of you and get some feedback, on the feasibility.

I have a W800, as many of the users here do. I was trying to think of a way to make use of that, as I have a pretty good antenna on it, and get very good range with it.

Next was the preverbial "light bulb" that went off. Couldnt a simple door/window sensor ( DS10a ) from X10 be used? My thought was to have a 12v relay that would switch closed when the car was on, and open when it was off. This realy could then be tied into the door/window sensors contacts.

Once that was done, when the "on command" was seen by HomeSeer, have it simply set a virtual device to "on". This would remain on until an off command was received. Then when the car is turned off, the command would then go to HS and again update that virtual device.

With this new device, you could tell who's car left, and at what time. You could also tell who's car, and when it returned home.

This seems SO simple, and I was wondering if anyone knows of any downfalls to this approach. I know the door/window sensors will report their status after a long period of time just to ensure the status is correct, but this shouldnt be a problem at all when the car was away.

So is this really something we have all overlooked up till now, has it been suggested before, or it just won't work for some reason??

If this will work, it would be less than $15 to monitor each car's activity. ($11 for the DS10a from Automated Outlet, and $3-4 or so for the relay)

Also thought of a new tagline
"WTF is usually bad for WAF." :p
Treetop, I did see that quite some time ago, and was thinking about doing it. I am not that good with a soldering iron, and, welll.... just look at the parts list for that project!

555 IC Timer $0.27

CD 4001 Quad NOR Gate $0.29

CD 4011 Quad NAND Gate $0.29

CD 4020 Binary Counter $0.49

LM 317 Voltage Regulator $0.45

Heat Sink Mounting Kit for LM317 Regulator $3.95

Heat Sink for LM317 Regulator $0.39

2n3904 Transistor $0.09

1N4005 Diode $0.04 (3 each)

4PDT 12 V Coil Relay $6.95

SPST 9 V Coil Relay $2.29

1.6K Resistor $0.99

270 Ohm Resistor $0.99

200K Resistor $0.99

56K Resistor $0.99

0.01 uF Capacitor $0.06

0.1 uF Capacitor $0.15 (2 each)

10uF Capacitor $0.06

330uF Capacitor $0.13

Fuse Holders $0.79 (2 each)

0.5 Amp Fuse $0.20 (2 each)

14-Pin IC Socket $.08 (2 each)

16-Pin IC Socket $.09

8-Pin IC Socket $0.25

PC "Bread-board" $3.29

Palm Pad Remote $5.99

Shew! As usual BSR has put together a fantastic tutorial. It's just a bit beyond my capabilities. (Somehow I go from 8 fingers and 2 thumbs, to 10 thumbs whenever I pick up a soldering iron :p )

With what I described above, the only thing neccessary would be to hook a relay to a 12v wire that becomes live when the ignition is turned on and ground the other terminal. Then simply wire the relay to the DS10A's input. Would take all of maybe 5 minutes. Another nice feature is you could run the 2 wires from the relay to wherever you wanted to place the DS10a, and the DS10a is still completely sealed, and quite compact.

One additional feature, is I have 2 friends with X10 setups here that I visit quite often. As the DS10a's are secutity devices that have to be paired with the system to work. Thus, I dont have to worry about turning something on or off when I go over to their house and visit, when I either start or turn off the my car hehehe :p

I just ordered a 3-for-1 deal on the DS10a's at X10 tonight to give it a try.
1) I am able to monitor if the car is leaving or arriving using some intelligent scripting, all using a single motion sensor :p
2) There is a hack to turn a motion sensor dusk sensor into a 'contact closure' type switch, so you could hook up the relay to that as well.

The DS10's will work, it's just that the W800RF is a requirement now, so you won't be able to process the car status using an Ocelot or other hardware controller.

Of course, the best solution is a Carpc with GPS, so it knows exactly where you are going :p I am actually working on software right now which can trigger events based GPS location.
So Dan will your home PC know where your car is or will the X10 signal originate from the car? So when I'm at this location send a "I'm home" signal type scenario?
electron said:
The DS10's will work, it's just that the W800RF is a requirement now, so you won't be able to process the car status using an Ocelot or other hardware controller.
The price you pay for this great stability that you Ocelot guys always talk about - limited support for other (new) hardware. :p
Well it's not just the Ocelot, I am also talking about the Elk, HAI, and other popular hardware controllers. Even the MR26A can't receive this signals :p I personally don't have this problem, but figured I would bring it up in case other people are looking at this thread and want to do the same thing.

What you are proposing should work, but only one signal would be sent (at least I believe this is true) with the DSA10 when the ignition was turned on or off. It is a little different from my car monitor because I will broadcast a signal as the car is pulling in the driveway. Also, my off signal is sent multiple times in a 15 second period so its sure to be received by the MR26a (or W800). Also, the car needs to be on for over five minutes in order for the off signal to be sent (just in case the car stalls immediately or you are having trouble starting it in the morning). Plus, you don't need a W800 to use it.

I do agree though that this method it not for everyone as it does require soldering skills. The main reason I posted this How-to was because I wanted something like this for my system and when I proposed this methodology, I got a lot of requests as to the details and following requests for schematics, etc...

I would be happy to try to hack the DSA10 if someone wanted to send me one, but I don't have a W800 (just use my trusty MR26a here). Will anything else pick up the DSA10 (RR501 plugin receiver or something like that)?

Anyway, I will help how ever I can!

Good luck,

As for BSR's design, I just wish we could establish a "universal standard mobile housecode" that all these mobile transmitters would use. With the range I get from my V572, I'm concerned about unintended macro triggering as other HA enthusiasts' cars drive by and "ping" my house. :p
Like the idea and love electrons idea about using gps even more because i know a few of the details such as automatically connecting to hot spots and updating your home pc with cordinates when the internet is available.

The way I am doing it is very easy but 'NOT' cheap. I am using the RFID system. Its cheaper than it should be because peter has been sending us free stuff all the time to test for him. So our $600 dollar investment just became worth it IMO because he is being nice and hooking us up every now and then.

Good luck with your project
i've taken a lazy approach to this. i have ds10a's in all the cars. the sensors check in about every 58 minutes. whenever one of the sensors doesn't check in (60 minute timeout), my system assumes the car is out. after the car is back, the sensor will check in as normal & the system will mark the car as home. this means, worst case, it takes the system about 60 minutes to know a car is home or away, average case is about 30 minutes. this is good enough for my needs right now and required minimal effort :p

the ds10a's are 3 for $19.99 @ x10.com
One advantage of the DS10a setup is that the codes are more unique, so if you drive by someone elses house, it probably won't trigger anything.
anybody know how to modify the ds10a so it reports in more frequently? is there a 555 timer or something like that in it? i rechecked my logs & the sensors report in about every 54 minutes. i'd like to halve that down to 27 minutes for the sensors in my car.
I would just get a relay, and tap the brakelight wire, since you usually hit the breaks right before you turn the car off (I have my motion sensors aimed at the brake pedal, and works great), or when you turn it back on.