As a solution to the "doorbell problem", I opted for the following components:
- one Xanura SAX15 potential free actor/interface
- three SH10 X10 remote chimes
One can connect the SAX15 to the existing doorbell circuit and plug the SH10's (one or more) into any power outlet, wherever the doorbell should be audible. Basically, the SAX15 sends a [unitcode] ON over the powerline if the doorbell button is pressed and sends a [unitcode] OFF when the doorbell button is released. The SH10's with unitcode [unitcode] sound their chime when they receive the [unitcode] ON command.
Benefits of this solution:
- Existing circuit stays, so there'll always be a working doorbell.
- Wired communication between actor and doorbell with no possible interference from neighbors (if X10 filters are installed, that is

- Additional doorbell(s) will work, independent of a PC with home automation software being switched on.
- If switched on, home automation software can easily register the doorbell event.
Of course there are many other solutions, such as the ones mentioned in http://www.domoticaforum.eu/topic.asp?TOPIC_ID=340, but I prefered the PC independent, wired approach.
So far, so good. However...
The SH10 turns out to be quite a strange device. It is not only a remote chime, but also a siren for X10 alarm systems. The manual is not very clear on the workings of this device (see http://www.waakzaamwonen.nl/catalog/red ... 2Fsh10.pdf), but what I found out is that the first time an SH10 receives an ON command, it sounds a doorbell sound (rather loud, but hey, some PUR-foam should solve that

However, if it receives another ON command, it sounds its siren (100 dB - which is very loud any very unpleasant) for about 10 seconds! Unless you first send it an OFF command. In that case, it will again sound its doorbell sound on the next ON command.
Because the SAX15 sends both an ON and OFF command, this theoretically shouldn't pose a problem. But what currently happens, is that sometimes one or more of the SH10's don't receive or register the [unitcode] OFF command sent by the SAX15 and will sound their siren when the doorbell is pressed a second or third time (as often happens when people become impatient - such as the TPG postmen

I can assure you, this is not a comforting situation and it does not help to increase the acceptance of home automation within my house

I don't think it has to do with interference/noise on the powerline. I have a three phase installation with filters (Xanura SFX40) on every phase and an active coupler/repeater (Xanura FKX) in place, as well as AFX2 filters to cut off all "heavy machinery" such as the dishwasher, laserprinter, etc. Furthermore, the CTX35 picks up the signals from the SAX15 without any problems.
I rather think it's some kind of timing problem within the SH10 that causes it to not register the OFF command? Or could it have to do with the fact that I'm using a three phase installation? The SH10 manual specifically states that the SH10 should be on the same phase as the actor. That's not the case in my house for all SH10's, but then again, also the SH10 that is on the same phase as the SAX15 sometimes sounds its siren. Or could the FKX repeater be the problem? Maybe it transmits the ON command twice as part of the repeater function?
Anyway, what I'd like to know: is the SH10 just one of those X10 devices to stay away from? Or could it work in my setup? Is it possible to disable the siren?
An alternative would be the SC546 X10 chime (only!) module, but as far as I know this device is not available on the European (230V) market.
Another thing I noticed is that if you press the doorbell for only a very short time, the SAX15 only seems to send a [unitcode] OFF command (at least that is what my CTX35 says) and thus only the original doorbell will sound (as no SH10 will respond), but that at least doesn't scare the hell out of me every time somebody rings the doorbell

Thanks in advance for any suugestions you may have! If I can't find a solution, I'm afraid I'll have to return all SH10's... (The SAX15 will stay though.)
Best wishes,
Lennart