Announcement

Collapse
No announcement yet.

Tip: getting a "trigger out" signal from a TV

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Tip: getting a "trigger out" signal from a TV

    I like having the TV serve as the trigger for all the other home theater equipment being turned on, since the TV is in the room, and when you press the remote, you can easily see if it's on or off.

    Our TV -- a Panasonic plasma -- like nearly all TV's, does not have a 12 volt trigger output. However, like most modern TV's, it *does* have a USB port (actually two). The USB ports are powered only when the TV is on.

    And, USB ports provide a 5V power for its connected devices.

    So, the trick/tip is to get a USB breakout terminal block. If you go to ebay, and type in USB breakout terminal block, you can find a variety of different ones. This way, you get a 5V trigger out signal, which you can use in a variety of different ways.

    For example, you can hook it up to a 5V relay to close a contact, which you can detect using readily available Z-Wave and other equipment. HomeSeer's ADIO device I believe can read the 5V signal directly (but don't quote me on that). And once you get the signal detected, you can of course do anything you want!

    The USB breakout terminal blocks are five bucks. A very cost effective solution.

    #2
    Here's a picture of my bench test. I'm having it close a relay, and will be detecting the relay closure (all the voltage detectors I could find typically go >9 v, and USB is 5, hence the relay).
    Attached Files

    Comment


      #3
      Originally posted by mikedr View Post
      Here's a picture of my bench test. I'm having it close a relay, and will be detecting the relay closure (all the voltage detectors I could find typically go >9 v, and USB is 5, hence the relay).
      Looks like it will work. Be sure and use a diode or some other means of clamping the reverse voltage as the field in the relay coil collapses (flyback), or you may take out the USB supply. Granted, the TV's output is probably protected, but some sort of protection is advisable. An opto isolator is the best bet.

      Comment


        #4
        Originally posted by rprade View Post
        Looks like it will work. Be sure and use a diode or some other means of clamping the reverse voltage as the field in the relay coil collapses (flyback), or you may take out the USB supply. Granted, the TV's output is probably protected, but some sort of protection is advisable. An opto isolator is the best bet.
        Do you think a detector circuit would offer this? I'm using this thing, which automatically sends an rs232 command to our receiver to turn it on.

        http://www.hallresearch.com/page/HR-4P

        Comment


          #5
          Originally posted by mikedr View Post
          Do you think a detector circuit would offer this? I'm using this thing, which automatically sends an rs232 command to our receiver to turn it on.

          http://www.hallresearch.com/page/HR-4P
          If you are just going to use the 5V as a pull-up to the I/O of the module and skip the relay, it will be fine. It is only the reverse EMF of a relay coil that can cause problems.

          Comment


            #6
            Originally posted by mikedr View Post
            I like having the TV serve as the trigger for all the other home theater equipment being turned on, since the TV is in the room, and when you press the remote, you can easily see if it's on or off.

            Our TV -- a Panasonic plasma -- like nearly all TV's, does not have a 12 volt trigger output. However, like most modern TV's, it *does* have a USB port (actually two). The USB ports are powered only when the TV is on.

            And, USB ports provide a 5V power for its connected devices.

            So, the trick/tip is to get a USB breakout terminal block. If you go to ebay, and type in USB breakout terminal block, you can find a variety of different ones. This way, you get a 5V trigger out signal, which you can use in a variety of different ways.

            For example, you can hook it up to a 5V relay to close a contact, which you can detect using readily available Z-Wave and other equipment. HomeSeer's ADIO device I believe can read the 5V signal directly (but don't quote me on that). And once you get the signal detected, you can of course do anything you want!

            The USB breakout terminal blocks are five bucks. A very cost effective solution.
            Does it have a network connection? Is it DLNA capable? If so, you can use the MediaController PI, which has a trigger when a DLNA compatible device comes on-line or goes off-line.

            Dirk

            Comment


              #7
              Originally posted by rprade View Post
              Looks like it will work. Be sure and use a diode or some other means of clamping the reverse voltage as the field in the relay coil collapses (flyback), or you may take out the USB supply. Granted, the TV's output is probably protected, but some sort of protection is advisable. An opto isolator is the best bet.
              I owe you a beer. I did research on this as a result of your post, and had no idea that there was such I think as back EMF, and that a simple 50 cent diode wired in parallel with the relay inputs could ensure it wouldn't fry anything.

              We are indeed using a relay, which will be hooked up to the contact closure detector of the Hall Research box I referenced in another post. The reason why is that the Hall Research box to do a pull up based on a voltage input needs a voltage of 9-24V, and USB is only 5. But I can set up the box to instead detect contact closure, hence the little 5V relay.

              Comment


                #8
                Originally posted by dcorsus View Post
                Does it have a network connection? Is it DLNA capable? If so, you can use the MediaController PI, which has a trigger when a DLNA compatible device comes on-line or goes off-line.

                Dirk
                Interesting. It has a network connection. I just googled the TV -- Panasonic p65vt25, an older high end Panny plasma -- and it appears not to be DLNA compliant, however.

                Plus, with that solution, you don't get to play around with fun relays!

                Comment


                  #9
                  Great idea...
                  Hector
                  ____________________________________
                  Win.2003 OS, HS3
                  BLDSC,BLstat,BLRadar,BLRamdom,BLOccupied
                  BLups,BLrain8,HSTouch,Ultrajones Weatherbug,
                  MyTrigger,ACRF2,W800,Zwave
                  AP800,Honeywell Stat

                  Comment


                    #10
                    Or as it's networked you could ping it with Blade or Jon00's network plugins.
                    cheeryfool

                    Comment


                      #11
                      You can also find very inexpensive ~$4 DC/DC convertors on eBay that will do USB (5V) to 12V. Most are designed for solar charging circuits.

                      Comment

                      Working...
                      X