[sci.electronics] Ever try linking digital outs from IR receivers?

lairdkb@mentor.cc.purdue.edu (Kyler Laird) (05/05/91)

I just completed an initial test of a project.

I've been using a Radio Shack IR relay that sends IR signals from the
bedroom to the living room.  Here the signal goes to two IR LEDs.  One
is just above the VCR, the other is on the side of the TV pointing towards
the stereo system.  Unfortunately, my S.O. just got some trendy oriental
screens to block off my work area.  This area includes the stereo shelves.

So...I can still control the VCR from the bedroom, but the path from the
TV to the CD player has been blocked by the screens.  I never did like that
arrangement anyway.

So I've decided to go more directly.  I want to have a couple IR receiver/
demodulators in each room send their output to a common IR 'bus'.  This
bus will feed the IR in of the other components.  All signals will be the
demodulated, TTL signals not the 40kHz modulated signals.

So far I've wired a three conductor 1/8" closed circuit phone jack to the
back of the CD player.  Ground, IR out and IR in are connected to it.  Also,
IR out and IR in are bridged when no plug is inserted.

This arrangement allows the CD player to act normally when no plug is inserted,
but when a plug is inserted, it presents the output from its onboard IR
receiver/demodulator, and accepts IR input to the control chip.  (Essentially,
I connected two wires to the path from the IR receiver/demodulator, then cut
the path between them.)

What I want to do now is perform similar operations on the TV and VCR.  Then
I'll connect the IR out from one or more to the IR in of each component.  I
will need at least two IR receiver/demodulators to place their data on the
line (one from each room).  I noticed that there is quite a bit of 40kHz
noise.  Will this be a problem with two on a line?

I can only find one of my RS IR rec/dem modules.  I connected it to the plug
to the CD player.  It works great.  The TV, VCR and CD are all recent Sony
models.  I am hoping that they all use similar IR modules.

Eventually, I hope to run all IR signals through a 6811.  This will allow me
to know from what area the signal originated, and act based on complex logic.

Another potential problem I'm wondering about is what I'll run into if I get
some IR headphones.  It seems obvious that these would operate on a different
carrier frequency.  If not, I'm in trouble.

Any thoughts?  Thanks!

--kyler