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TV Power Detector Purpose: To know when a TV is on or off. (Or dryer, water heater, lights....) Home Automated Living’s HAL 2000 supports speech recognition therefore entire macros can be carried out with simple phrases. Knowing whether a TV is on or off is useful when creating rules with HAL 2000. For instance if the telephone rings and the living room TV is ON HAL can MUTE that television’s audio. Of course for this capability you will need an IR distribution system. I have created rules in HAL that evaluate all the TV’s in the house. If the doorbell rings any TV that is turned on tunes to the front door camera (Channel 88) for 1 minute then JUMPS back to the channel it was previously on. If you decide to use an intelligent open air microphone system, which has microphones located throughout the house listening for your commands, it will be important to shut off the microphones located near TV’s, and stereos when these devices are on. This is useful if you spouse is watching TV in one room and you want to communicate with HAL in another. I searched for off-the-shelf solutions, but was disappointed to find they were relatively expensive. Since I have 7 televisions in the house I needed a solution that would;
Using a current sensor, universal module and a power cord I solved the problem. I purchased a three conductor extension cord that has three outlets. A grounded extension cord is recommended since you may also have to plug the TV into an AC line noise filter if the TV interferes with the X-10 signals. (Many of my TV’s needed this for reliable X-10 signaling.) An extension cord is used since I didn't want to cut up the TV’s power cord. I found one at Home Depot made by Woods that was ideal, it has a product number of 2865. I searched high and low for an inexpensive current sensor that would work with a power-flash interface module. I found a current sensor made by Cutler Hammer, which is listed on the parts list portion of this web site.
Unfortunately this current switch will not work with the X-10 power-flash interface. I have not tested it but I would assume a CR-8420 would work with the power-flash interface. If anyone finds a inexpensive current sensor that can trip the power-flash interface using this method let me know which one you used and I will post it here.
After making sure the extension cord was NOT plugged in, I simply cut the extension cord in half and trimmed off about two feet of the outer covering of the cord which revealed the three insulated conductors inside. These 3 conductors are HOT, Neutral and ground. I located the HOT conductor, which is connected to the PLUG with the SLIM blade. (Polarized plugs have a fat and slim blade so they can only be plugged in one way.) On the woods brand extension cable shown the BLACK wire is HOT. This HOT wire needs to be wound through the current sensor as many times as possible. I had to be sure to face the current sensor towards the load (TV plug) as illustrated in the picture and made sure to wrap the HOT wire through the sensor as many times as possible. The more times it is wrapped, the more voltage it will provide to trigger the power-flash interface. This is important if the TV is small and doesn’t draw a lot of power. Of all the TV’s in my house there was only one 9-inch TV that wouldn’t trigger the universal module since it didn’t draw enough current. I soldered the 3 wires back to their respected mates using heat shrink and electrical tape to ensure there were no bare wires. Warning: This is high voltage. You can get shocked, electrocuted or KILLED if you don’t take the time to do this properly! I am not responsible for your work.
I cut off the plastic connector on the cutler hammer current sensor. I then connected the Black wire to the Negative (-) connector and connect the White wire to the Positive (+) connector on the power-flash interface. The red wire is not used. I had to set the INPUT to A (Voltage) and the MODE to 3 (Send on and off command) on the power-flash interface. Next I Plugged the power-flash interface and TV into the into the extension cord and plugged the extension cord into the wall. When the TV is turned on the X-10 command will be sent. If the command is not received it is likely that you will have to plug in a noise filter into the extension cord and plug the TV into the noise filter. This is the brown box shown in the picture above. I use the house code "P" then assign a number for each TV that is monitored. I then set up a "sensor" in HAL for each TV that is assigned to the unique X-10 address. For instance I have a "FAMILY ROOM TV" sensor. Now the sensor can be used as a "Trigger Event" to fire a rule or the sensor can be used as "Secondary Condition" to evaluate the on/off status of this sensor.
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Since this article was originally published, it appears that the Cutler Hammer
current sensor is hard to get. I located
an improved current sensor that actually costs less. Instead, use this 
