My house makes its own decisions about lighting levels based on many things. To improve the accuracy of these decisions, I need more sensitive motion input to my lighting macros than what hawkeye detectors can provide. Increased sensitivity allows me to lower light-out times and eliminate the occasional motion "miss" that hawkeyes are notorious for, ensuring 100% light-on response when someone enters a darkened room. Plus, having unobtrusive ceiling mounted sensors looks much more professional than Hawkeyes with their big "X10 Pro" logos...
My search led me to test many PIR and multi-sensor motion detectors. I finally settled on the Honeywell 997. Like most security oriented detectors, this one features a normally closed relay which opens when motion is detected. Sweet. Just dial up one of the many Hawkeye mods that turn this device into a contact-close sensor and Voila!
Too bad it didn't work. The sensor mods out there replace the Day/Night CDS with a switch/load resistor. Unfortunately, the Hawkeye isn't programmed to instantly react to a change here. In fact, it took about 4 seconds. Way too slow. So, I decided to engineer my own mod targeted at the PIR input to the PIC.
When finished with this little mod, a Hawkeye will instantly react when the connection breaks and will send an X10 on about every 5 seconds until the connection is closed again. This makes it a perfect wireless transmitter for just about any "fail safe" security device you can think of.
Here's how to do it:
Start by removing a 1meg resistor, the CDS cell and the green LED. Here's the locations:
Next, solder a 1K quarter watt pullup resistor between +3 and the anode location of the now removed green LED. This is the PIC's GP0 input and needs to be high to cause code transmission. Here's a pic showing this:
Finally, connect a 2 conductor wire between ground and the GP0 input. Just solder it to the resistor on one side and the convenient ground jumper near where the CDS cell was as shown:
Now notch out the side for the wire to exit:
and Bada Bing: a highly sensitive wireless X10 transmitter for the myriads of fail-safe relay based sensors out there. No more 5 second lag between sensor re-arms either. Every time the contact opens, this "pwn3d" Hawkeye will instantly transmit the programmed House/Unit code.
So how am I using it? Think cost-effective contact based input to HCA or any other HA solution that is compatible with a W800RF32. Check out the post containing a full writeup in the Fortress showcase thread for details. That post is located here.
Enjoy the mod!
Edited by kwilcox, 26 May 2009 - 07:50 PM.