I hope I'm on the appropriate site.

Does anyone know what this thing is?

It has a mini mono plug. The white square is slippery..but it is not covering double-sided tape. A white LED did not light up when I plugged it into a mic input on my PC. I thought there were little holes and it might be a mic but they are small indentations, not holes.


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  • \$\begingroup\$ Could be anything, but maybe a piezo mic? \$\endgroup\$ – Wesley Lee Mar 23 '19 at 19:16
  • \$\begingroup\$ When I plugged it into a PC I tried to record with it...but nothing. And why the LED? \$\endgroup\$ – Steve Wellens Mar 23 '19 at 19:21
  • 2
    \$\begingroup\$ I've seen similar things before used to put remote photodiodes on a remote-operated device. I have one on an HDMI splitter and it uses the same connector. I can't say for sure, but I'm guessing the LED is a photodiode (or an LED being used as a photodiode) and this is meant to be plugged into one very specific device and nothing else. A picture showing the "LED" might be a good idea, by the way. \$\endgroup\$ – Hearth Mar 23 '19 at 19:23
  • \$\begingroup\$ The bottom picture includes the LED. Maybe I should have angled the shot. \$\endgroup\$ – Steve Wellens Mar 23 '19 at 20:42

That's an infrared transmitter for extenders or control systems. That plastic chunk with the IR LED gets glued on a device like TV or Blu-Ray player so that it shines on the device's IR receiver.

  • \$\begingroup\$ Thanks! I guess I can throw it in my junk cables box. \$\endgroup\$ – Steve Wellens Mar 23 '19 at 20:43

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