Schematics for the H IR Extender

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mad_ady
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Schematics for the H IR Extender

Post by mad_ady » Mon Sep 19, 2016 9:43 am

Hello all,

I'd like to reuse the IR Extender cable that came with my H6400 TV and transform it into an IR blaster to control my AC unit. But, to do this I'd like to understand how it's built (does anyone have a schematic?) and also what voltages/currents I can apply to it to work.

I will be controlling it from a Odroid XU4 which has TTL1.8V logic, but I'll be using a transistor and can feed it from 5V (and probably a max of 100mA).

I'm guessing the limited range when using it to enter the extended service menu is due to the limited current it gets from the headphone jack, right? From what I've read the voltage could vary from 0.3V to 2V, and current should be around 15mA: http://electronics.stackexchange.com/qu ... om-a-phone

Anyone else tried this already?
H6400, firmware 2602.2 downgraded to 2130

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mad_ady
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Re: Schematics for the H IR Extender

Post by mad_ady » Tue Dec 06, 2016 3:42 pm

Seeing that nobody knows this I opened up the IR extender (there is an adhesive tape on the back) and opened the two screws connecting it. If you want to open it yourselves, take care that the screws are quite tight. Inside there are 5 IR leds (connected in parallel), 4 of them in a circular pattern and one central LED. They are powered directly from the cable, no resistors in sight.

Here are some images of the inside of the IR extender and an approximate electrical diagram.

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Now, the problem is identifying the parameters of these IR LEDs - what is their direct voltage drop and their maximum forward current. From various sites online I could gather that the voltage drop for an IR LED is between 1.4-1.6V and the current is around 50mA. Any ideas how I can test these in a controlled fashion in order not to burn the LEDs out?

My plan is to use the extender (which is about 3m in length) to control an AC unit. The IR leds will be around 20-30cm away from the AC unit's receiver.
I'm guessing I won't be needing 50*5=250mA of current, because when using the extender with a PC to enter the service menu, the PC's headphone jack is not outputting more than 20-30mA.
H6400, firmware 2602.2 downgraded to 2130

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mad_ady
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Posts: 244
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Re: Schematics for the H IR Extender

Post by mad_ady » Sun Jun 18, 2017 12:34 pm

Ok, I've managed to use the IR extender to create a "smart" internet-connected AC unit. Details about the hardware/software build are here: https://forum.odroid.com/viewtopic.php?t=26799
H6400, firmware 2602.2 downgraded to 2130

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