msg said:
That was my initial (internal) reaction to that suggestion until I
suspected
that the respondent meant to check for digital circuit RFI which the remote
may radiate and be detected by the radio (sometimes FM works better for
high clock frequency circuits, and certainly a shortwave radio would permit
tuning to a sweet spot to listen to digital noise as the various buttons
are pushed).
I will try it with various remotes and report the results; to be useful,
the noise patterns would need to map well to button presses.
*AND* be radically different if the IR LED is faulty. That *may* be the
case if its open circuit, but if its gone short, I'd not expect much
change. At best its a quick way of checking the RC isn't totally brain
dead.
I always favoured an IR photodiode mounted in a BNC plug with a black
rubber shroud (off a large croc clip and cut to length) to exclude
ambient light. It used to live on the 3rd channel input of the scope
when I was doing TV work. Nice clear pulse signal as the scope's
1M/30pF integrated the ~40KHz carrier so easy to check the different
buttons gave different signals.
For a rough function check I'm sure most of us know that IR is visible
on most mono and some colour video cameras so just point it at the
shop's CCTV and press the buttons. If using an unfamiliar camera try a
known good RC first to confirm the camera can see IR.