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How To Amplify IR Emitter to Blaster

post #1 of 6
11/24/10 at 6:14am
Thread Starter 
Hi,

In my current set up I have all my AV Equipment in a stairs cupboard and the TVs distributed in the various rooms. I currently have IR from the remotes over CAT6 into the cupboard. However I now need to transmit an IR signal from a HTPC in the cupboard back to the rooms.

The device that emits the IR signal uses a low power IR emitter (USB UIRT 3.5mm emitter). I am again going to use CAT 6 to extend the emitter, however I need the signal at the room to blast like a normal remote to control all TV and other room equipment.

Is there any way to amplify the IR signal and convert to a blaster type? Ideally I would like the solution to be wireless.

Thanks for any advice,

Gary
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post #2 of 6
11/24/10 at 6:23am
What are you using right now to distribute ir from the ir receivers in each room to your equipment? Just splice the pc ir output into that system.
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post #3 of 6
11/25/10 at 2:17am
Thread Starter 
Hi,

Thanks for the quick reply. I'm using a HDMI matrix with built in IR distribution. This receives signals from the rooms and controls equipment in the cupboard. However this system does not blast out the signal or distribute the other way.

I need to come out of the low power emitter (from the USB UIRT) and amplify it so that I can have a blaster in the corner of the room. Can IR signals be amplified in this way?

Thanks,
Gary
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post #4 of 6
11/25/10 at 3:16am
Thread Starter 
Hi,

As a follow up I have come across this amplifier circuit:


Click here to see guide

I'm planning on modifying this so that it has 3 IR LEDs in parallel, reduce the resistance to 8 ohms to compensate and power the circuit from a 9v battery. I can then either place the entire circuit in the corner of the room and extend the cable entering the circuit or perhaps better, extend the cable to the 3 IR LED's and have the circuit in the cupboard.

This hopefully should mean that I can blast IR commands out from the cupboard to the room with all the equipment.

Where it gets confusing is the existing IR distribution in the HDMI matrix will return the signals back to the cupboard

Thanks,
Gary
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post #5 of 6
12/3/10 at 2:09pm
I'm not up enough to say whether the circuit will work. But why don't you just buy a commercial product? I think I've seen such on the websites of several companies. For example have a look at http://www.xantech.com/Infrared/Infrared/IREmitters/ and see if the J-Box or Shelf-Top IR blasters would meet your needs.

Give that you are blasting into the cabinet as well, are you absolutely sure you won't have positive feedback loop causing the Bad Thing (TM) to happen? At least you won't get the screaming wedding-DJ whine. But surely this would cause your system to not work on a continuing basis, or worse.
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post #6 of 6
12/3/10 at 4:43pm
Hi Gazzas,

I don't think you'll run into a problem with a feedback loop if you use your USB-UIRT for both input and output to your HTPC. I believe the USB-UIRT is 'blind' when it's transmitting.

The circuit you provided probably will work, for a while that is. Based on 12V, the 15 ohm current limiting resistor, and a typical IR LED, the transistor would be supplying around 600mA to the LED. The problem is the 2N3904 transistor is only rated at 200mA. It would be better to substitue a higher current 2N2222, which is rated up to about 600mA.

Likewise, adding additional LEDs in parallel and dropping the value of the current limiting resistor is bad for a number of reasons. If you want to triple the output of this circuit, use individual transitors and current limiting resistors for each LED, or, select a higher current handling transistor and use individual current limiting resistors on the cathodes of each LED.

That being said, I think a single IR LED being driven at 600mA would be more powerful than most remote control emitters, and will probably work fine for your needs.

Jonathan
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