How to test infra-red LEDs

[Yorkie]

A tip that might come in handy if a remote control for a TV, DVD etc seems not to be working. We can't see the infra red light from the LED so can't tell if it is lighting up, but a digital camera can see it. If you point the remote into the camera lens and press the button on the remote while looking through into the camera screen, you'll see that the LED lights up (if of course it's not a dud!).

I learned of when a friend wanted to put a pinhole camera in a blue-tit box to view and record what was going on inside. He asked me to make up a board with several infra-red diodes so that he could illuminate the inside of the box to enable the camera to record the activities. Like us, the birds can't see the infra red, but the camera can, so the presense of intra red doesn't disturb the birds. By looking at the LEDs through my digital camera viewfinder when testing the wired up board with the LEDs on it, I was able to confirm that the LEDs were lighting up.

[tiv48]

an other way of testing ir remote controles is to use a mw radio tune to a quiet part of the band hould remote about 2" away and you will hear the pulses
rob t

[Steve_P]

Have you got an old Camcorder? You can see it....

Cheers,

Steve P.

[Mark Hennessy]

Most modern consumer cameras and camcorders have IR filters built into them, but if you're lucky, the IR LED will be fairly "broadband" in its spectrum. Of course, broadcast cameras with 3 sensors and high quality filtering don't respond awfully well.

IR cameras are used in virtual sets to track the position of the broadcast cameras so that the graphics engine generating the background can update this as the camera moves around. The fact that broadcast cameras don't respond to IR is a distinct advantage here...

[Alistair D]

Mobile phone cameras are very good for this probably because they do not have much IR filtering.

Al

[pwdrive]

The infra red always used to work with the video cameras back in the eighties, it used to be our standard test in the TV workshop.

Lawrence

[Paula A]

Phone cameras.. never seen one fail to see the ir leds.. and very often the laser beam effect as well.

I believe it was LLJ who gave us this trick at the end of the 70's