A-Bus IR LED flicker

I was thinking about getting a Squeezebox2. I have a curiosity question: Are you using it through a Russound 'local source' wallplate, or do you have it connected directly to the A-H484? If it's the latter, do you control it via IR through the keypads? Is it convenient to use when you can't see the display?

Thanks.

Thanks for your response. After covering the IR sensor with my finger, the LED continued to flicker. Alas, I'm afraid I'm not inclined to solder a capacitor across the terminals... A followup question for you - do you think the flicker could have resulted from the CAT5 wire touching electrical wiring inside the walls of the house? Bob

I have the Squeezebox connected directly to the AH484 hub. Works great tucked away in the basement. For me, the key is using my laptop (via wireless), which is almost always running (usually from the kitchen), to control the song/station selection. Of course I can use it from any ABus-enabled room in the house. As for the remote, yes, I've been able to use it to cycle through my playlists - and yes, I'm doing that blindly. Works pretty well after you've setup playlists based on internet radio stations or your MP3 collection. Hope this helps Bob

Dave, No fluorescent light or sunlight. I tried this at night, with a dark room. Bob

Your finger will not block all IR. Your body also emits IR.

Crosstalk from 60Hz is an unlikely culprit.

Is there a fluorescent light or sunlight source near the sensor?

"Bob N" wrote:

Possibly a little stray voltage across the LED light. If you had a multimeter you could check the potential across the led.

Most LEDs operate on a 1v - 3 v dc supply.

Or it could be receiving some extra IR into the sensor and indicating that. To check this, put your finger over the IR receiver window (usually little tinted window) and see if the LED still flickers.

To fix the DC issue, you could solder a capacitor across the terminals, making sure to get the polarity correct and using a cap like a 470uF 25v. This will filter the voltage turning the LED on.

To fix the second, you will need to locate what is generating the extra IR and move it, or fix it.

Everything emits IR. But that won't affect your IR controlled equipment.

Waitaminute...we need a tech timeout.

We emit far-IR radiation, but this sensor is looking for near-IR light. Very different things, very far apart on the spectrum. A remote control sensor cannot ever detect IR radiation. Otherwise PIR motion sensors and IR receivers would be the same, and they're not.

-John O

Pulse meters that slip over your finger use IR in the 900-925 nanometer range. They transmit the IR through the finger and receive it on the other side. Surges in blood flow modulate the IR at your pulse rate. Consumer IR uses 940 nanometer IR. A finger is not the best choice to block 940nm IR although it will attenuate it. Even black plastic may not block CIR.

We emit IR in the 8-14 micron range but, as I understand it, it's the optical filtering used that determines what wavelength an IR detector responds to rather than the detector itself. I have no idea (and suspect you have none either) about the specs of the filter/detector used in this application. I assume (as you have) that it's designed for consumer IR but I don't know how it may be affected by extremely near far-IR. Again, I don't think a finger is the best choice for a filter.

Vishay has a good white paper on interference sources for their Consumer IR receivers.

C>> Your finger will not block all IR. Your body also emits IR.

A few months ago I was digging around the websites of manufacturers for IR receiver devices, both near-IR sensors and pyroelectrics, and I didn't get that impression. They seemed proud of their out-of-intended-band rejection specs. The narrower the detected band, the better. Maybe the A-Bus receiver is a POS that detects anything, though, who knows. Bottom line for me, if a CIR is going to detect 8-14 micron IR, it's defective, and impressively so.

So anyway, a finger might be what, -20 dB? That should work to block nuisance interference that slips by a filter.

-John O

Covered it with black tape...no dice. Still flickering.

You might be surprised by...

Will do...thanx

Connections are solid. Called Russound. They quickly responded that the CAT5 is very likely picking up some 'stray voltage' on the way up to the bedroom. A consultation with their engineer, and the suggestion is to try to attach a ferrite bead to the wiring at either end... I'm up for anything (beats ripping the wall open), so off I go to Radio Shack.

That detector isn't responding to far-IR, it's very likely responding within its rated near-IR range.

The nichrome is emitting visible light too, and in between visible and far IR is.....near-IR light. It's no secret that incandescent lamps emit some IR light, which this experiment is clearly proving. A Wratten #87 filter between the wire and sensor will remove 99.9% of the visible and near-IR, making conclusions possible.

Who's the prof at Beloit...he needs a tweak. :-)

-John O

Apparently there's no way to test this because nothing stops IR light, and the sensors detect everything. :-P

Seriously though, there's something going on inside the module, or coming in through the Cat5. Make sure the Cat5 connections are solid, especially ground. Then call Russound and see what they suggest.

-John O

Well. I tried the ferrite beads. No change in the flicker. This is nuts. Back to Russound to see if they have any other ideas.

If the unit is still in warranty give me a call. I'll get you a replacement piece from Russound.

Thanks very much Robert. I'll contact you directly.