Need Infrared LED expert Opinion...

[Jim Flanagan]

Hello..
I would like to build an infrared repeater device for my home theatre
setup. My big screen TV has an output on the back for the use of adding
additional, hardwired, IR led emmitter cables (Although I plan on
building an interface so that many IR emitters could be attached and not
'tax' that TV's ability to drive the LEDS). These individual cables
would be routed to the various components and attached directly near the
IR receiver window. My question, is their enough IR energy from a
generic RED led to activate the IR receiver(s) since the proximity of
the led emitter is so close? If so, would I need to drive the red leds
with an abundance of current?

Your help is appreciated.

Jim

 

[Rich Grise]

On Mon, 03 Jan 2005 18:56:21 +0000, Jim Flanagan wrote:

Hello..
I would like to build an infrared repeater device for my home theatre
setup. My big screen TV has an output on the back for the use of adding
additional, hardwired, IR led emmitter cables (Although I plan on
building an interface so that many IR emitters could be attached and not
'tax' that TV's ability to drive the LEDS). These individual cables
would be routed to the various components and attached directly near the
IR receiver window. My question, is their enough IR energy from a
generic RED led to activate the IR receiver(s) since the proximity of
the led emitter is so close?

No.

If so, would I need to drive the red leds
with an abundance of current?

Why not just use IR LEDs?

Your help is appreciated.

You're welcome.

Good Luck!
Rich

 

[John Woodgate]

I read in sci.electronics.design that Jim Flanagan
<jflan@tampabay.rr.com> wrote (in <pzgCd.175938$8G4.106801@tornado.tampa
bay.rr.com&gt about 'Need Infrared LED expert Opinion...', on Mon, 3 Jan
2005:

My question, is their enough IR energy from a
generic RED led to activate the IR receiver(s) since the proximity of
the led emitter is so close? If so, would I need to drive the red leds
with an abundance of current?

You can easily get proper IR LEDs. Do you need to use red ones for some
secondary reason?
--
Regards, John Woodgate, OOO - Own Opinions Only.
The good news is that nothing is compulsory.
The bad news is that everything is prohibited.
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk

 

[Jim Flanagan]

John Woodgate wrote:

I read in sci.electronics.design that Jim Flanagan
jflan@tampabay.rr.com> wrote (in <pzgCd.175938$8G4.106801@tornado.tampa
bay.rr.com&gt about 'Need Infrared LED expert Opinion...', on Mon, 3 Jan
2005:

My question, is their enough IR energy from a
generic RED led to activate the IR receiver(s) since the proximity of
the led emitter is so close? If so, would I need to drive the red leds
with an abundance of current?


You can easily get proper IR LEDs. Do you need to use red ones for some
secondary reason?
Yes.. I surely realize that. I should have mentioned that I have a

'bushel' of regular red leds and simply didn't want to wait for delivery
of the IR versions.

Jim

 

[nospam]

Jim Flanagan <jflan@tampabay.rr.com> wrote:

My question, is their enough IR energy from a
generic RED led to activate the IR receiver(s) since the proximity of
the led emitter is so close? If so, would I need to drive the red leds
with an abundance of current?

There will be sod all IR energy from a red LED so the question should
probably be how good (or bad) are the IR filters on the receivers.

Check out a datasheet for a BPW34F which is a cheap photodiode with built
in IR filter. It shows zero % response below 760nm. The 'coldest' red LEDs
are about 700nm. I haven't seen a spectrum for such a LED but I guess
between the LED and the filter you will be about 10,000:1 down on an IR
LED.

If you have a 'cold' red LED and poke it right next to the receiver there
is some chance it will work.