According to the schematic you posted, the LX IR receiver board doesn't have a demodulator. Instead, it is outputting the raw 455 kHz pulse train, modulated by the actual IR command bits. The hockey puck receiver on the other hand outputs only the IR command bits (you can think of this as the difference between an antenna amplifier that outputs a radio signal and an actual tuner that outputs audio, if that sounds more familiar to you).

Apparently the demodulation is done by the processor (IC3 above) further down the line in the LX. I believe you could do that with the Arduino as well (it is much faster than the old microcontroller in the LX), but the ready made libraries won't help you there, they all expect the baseband IR pulse train. What you need is a TSOP7000 receiver chip which is an integrated receiver for the 455 kHz carrier frequency, or the full-fledged B&O receiver/transceiver.

Hmm, even worse then...

but the TSOP7000 and TSOP5700 are both discontinued since long. and even if there are some selling it I would only buy it is someone could recommend from where.

so it will not help me adding the 4resistors and transistor in the signal path 😡

makes me wonder... I read about someone who used a IR from a Beovision 8802 as input to a lintronic box, and connected it where the hockey puck beolink IR receiver normally goes... maybe the older BVs had the demodulation on the same PCB

I put in small orders from these ebay sellers, no problems at all. All delivered fine within reasonable time:

link

link

BeoLignage wrote:

makes me wonder... I read about someone who used a IR from a Beovision 8802 as input to a lintronic box, and connected it where the hockey puck beolink IR receiver normally goes... maybe the older BVs had the demodulation on the same PCB

Some of them probably did, yes. As somebody (Johan?) said in the other thread, these B&O receivers that are constructed from discrete components are a lot more sensitive than the TSOP7000, and we're all used to the comfort of not caring where the remote is pointing at. The LX front-end would therefore be well worth using if the demodulation could be solved. The AVR processor on the Arduino would be plenty fast to do it in software, but probably not fast enough to do this using interrupts like the regular library does; it would need some skilled low level programming.

EDIT: I believe 8802 used the old Mars bar remote controller - it is completely different from Beolink 1000 and uses 30-50 kHz carrier as far as I know.

I've bought from here http://darisus.de/

Right, these units are great for tinkering and figuring stuff out, but I use MCL2 transceivers instead in the final "product". Better reception and a nice looking package.. and they are not that expensive considering that people sell MCL2As for a couple of hundred SEK.

The signal from the transceiver is more or less the same as the demodulated IR signal, so using a TSOP7000 for development is fine.

As Mika says, demodulation is certainly possible on the Arduino, but you wouldn't have time to do much more. Interrupts are too slow, and delay takes too long. What you would have to do is just loop and read the state of the pin as fast as possible and track the changes in state. I don't recommend it.

Get a TSOP for development and an MCL2 transceiver (or puck) for your "product".

/  Johan

The circuit diagram of the LX2802 IR Module shows a simple but complete strait AM receiver for a fixed frequency of 455 KHz  😉

At the left the input filter, then in the middle another filter with an amplifying stage and between the last two transistors the received high frequency signal is rectified and low pass filtered before the last transistor makes a nicer and stronger signal. There's also a feedback to manipulate the gain of the 'HF' amplifier (an AGC function)  🙂

So the module should work with the Arduino program if the module itself is working correct. It might be defect.

An alternative is the Videosensor for the VX5x00 VCR recorder or an MCL2 sensor. Both have the great sensitivity for Infrared signals like the 'puck'.

But as stated before a TSOP7000 or TSOP5700 (the SMD version of the former) might work for testing at the workspace but for the final 'product' a real B&O reciever is worth of it.

RaMaBo wrote:

At the left the input filter, then in the middle another filter with an amplifying stage and between the last two transistors the received high frequency signal is rectified and low pass filtered before the last transistor makes a nicer and stronger signal. There's also a feedback to manipulate the gain of the 'HF' amplifier (an AGC function)  🙂

You are, of course correct - forget my earlier talk about the missing modulator...

Then, perhaps only the signal polarity is reversed to what the Arduino library expects from an integrated receiver?

I think you may be right, Mika. Counting the inverting amplifiers in the circuit it seems that last transistor right before the input is necessary to make it active low (which I think it should be).

Again, correct me if I'm wrong.

/  Johan