RE: RE: IR Transmitter boards.

[BROUGHTON NICK <nick.broughton@xxxxxxx>]

Doh...

Thanks Keith.

I hadn't thought of that one, despite getting a feedback loop when
they were on the workbench!  I plan to test it all, in location,
before doing any soldering anyway, but maybe it's time for a rethink.

Hmm, could I use a transistor in the 'client' module to 'disconnect'
the IR LED when the TSOP's output pin goes low?

Regards


-----Original Message-----
From: keith.doxey [mailto:keith.doxey@xxxxxxx]
Sent: 23 November 2000 15:15
To: 'ukha_d@xxxxxxx'
Subject: RE: [ukha_d] IR Transmitter boards.


Nick,

There is potentially a serious flaw with your idea if I read it
correctly.

Driving multiple LED's is easily accomplished using extra transistors
to
buffer the signal. The "problem" with your idea is that of having
the
IR
LED's in close proximity to the TSOP.

When first switched on everything would be fine.
When the first IR signal is received ALL the LED's would transmit and
be
picked up by the adjacent sensors which would tell the transmitter to
drive
the LED's.

At best you would probably have an unstable and unreliable system, at
worst
it could permanently transmit IR which would ultimately lead to the
demise
of your IR LED's and also jam any IR transmissions you were trying to
send.

Two Way IR is basically a no-no(Duplex). Bi-directional IR is OK
(Half
duplex)
You need to ensure that recievers are disabled when IR is being
transmitted
from the same location.

I would try a mockup BEFORE a full blown installation just incase it
isnt
going to work.

Depending on how the IR modules were constructed you may be OK if the

transmitted IR doesnt get picked up by the receiver but I felt I
ought to
make you aware of a potential pitfall.

Keith

-----Original Message-----
From: BROUGHTON NICK [mailto:nick.broughton@xxxxxxx]

My current plan (it's been changing about once a day, the last few
days) is
to put the 'transmitter' at node 0.  The resistor and zener for the
TSOP
would also be there.
12V would be supplied directly to the 'transmitter'.
Then I would use CAT5 and send one pair for IR LED, one pair for
visible
LED
(confirmation), one pair for TSOP output and one pair for 5V supply
to
'client' modules.  These modules would simply contain 2 LED's and one
TSOP
and (probably) an RJ45 socket, making them suitable for receive,
transmit
or
both.


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