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IR Emitter Polarity Test

joelwjoelw Junior MemberPosts: 175
A good test for IR emitter polarity is to use your DMM (Digital Multi-Meter) in diode check mode.

With the IR emitter wires disconnected from the control system, connect the DMM leads to the IR emitter wires. If you don't see around 1.5V, flip the leads.

Red = Signal
Black = Ground

The reason this works is that an IR emitter is just a light emitting diode (LED) in the infrared spectrum.


  • John GonzalesJohn Gonzales Junior Member Posts: 609
    Can also use continuity on your DMM or ohmmeter, if polarity is correct then continuity reads near 0 ohms, if polarity is incorrect then continuity reads open or infinite. Fluke DMM's actually beep in their diode test mode to let you know that diode is good and polarity is good. Also, another quick test is to use a tone generator with continuity function if a meter isn't handy. Most field installers will have this with/near them all the time. Set toner to Continuity, and touch leads of the IR emitter. The toner's light will light up on correct polarity, and will not light up on incorrect polarity.

  • VLCNCRZRVLCNCRZR Senior member Posts: 216
    Another handy test for IR...

    An easy quick check to see if your emitter is sending anything is to use your
    cell phone camera to watch the emitter.

    Dont forget, the human eye cannot see IR wavelengths, but a cameras pickup
    device is sensitive to IR and shows it very well.
  • jjamesjjames Just another dude Posts: 2,906
    Hmm . . . so are you guys noticing the change in polarity with recent AMX IR emitters? Like I said in another post, our installer (who's been installing AMX for quite some time) is noticing they're backwards now. I sit at a computer all day - so I wouldn't know from personal experience, but that's the word I'm getting.

    Regardless, this shouldn't be a problem - not sure why AMX (or the manufacturer) would all of a sudden change polarities. Certainly something we should haven't to test for. That'd almost be like . . . hmm, are pins 2 & 3 on the NIs transmit/recieve or recieve/transmit this time? Just something we shouldn't have to deal with.
  • NMarkRobertsNMarkRoberts Junior Member Posts: 455
    VLCNCRZR wrote:
    An easy quick check to see if your emitter is sending anything is to use your cell phone camera

    Yeah, digicams too, but they don't seem to work on IR emitters, just on the regular remotes - ?
  • joelwjoelw Junior Member Posts: 175
    What also works if you don't have an IR sensitive camera handy, or a Radio Shack IR card (waste o' $), is the inductive amp from a toner set.

    Listen anywhere on the wire, from output to emitter. It makes a very distinctive sound when IR data is being generated.
  • DHawthorneDHawthorne Old Timer Posts: 4,584
    They are starting to make digital cameras with a built-in IR filter because they give a "wet T-shirt" effect sometimes if you take a picture of a woman not wearing a bra and has a relatively thin blouse. Though there are times you might like this effect, it won't do for family gatherings, and I imagine the camera companies get complaints (to say nothing of the pervs deliberately using this to "peep").
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