The likes of which I am totally unfamiliar with. Still, HOW is the TS measuring the voltage?

Just with a voltmeter where BUS/BUS enters his flat... of course he can only see the DC offset...

 

If you are trying to sense whether the main circuit breaker is off, why are you using the doorbell? Why not use any outlet in your house and sense the mains voltage with a relay?

its a building with multiple flats... i cant do that.

 

Just with a voltmeter where BUS/BUS enters his flat... of course he can only see the DC offset...

yes thats how i did it, using Voltmeter on Bus/bus , and it was set to DC.

Well but even its proprietary etc, why one optoled which consumes almost nothing might be an issue?

Thanks

 

Well but even its proprietary etc, why one optoled which consumes almost nothing might be an issue?

Its not what it consumes that's the issue... its what effect it has on the signalling on the wire - and, since that 30v will be reversing even though you can't see that, what effect that might have on the opto.

 

30v will be reversing even though you can't see that, what effect that might have on the opto.

you mean change the polarity?

so basically i cant do anything ... ?

manual says, see below, but i have no clue what are SA,GND... when i measured it there was no voltage.

 

The way to determine the presence of activity on a digital line with an unknown data format and protocol, would be with a lightly coupled audio monitor. Digital data bursts will be obvious as noise, total silence will imply no activity because of no supply power. THAT would be my suggestion. This is a scheme similar to that used for sensing abandoned computer wiring in large rental space office buildings.

 

The way to determine the presence of activity on a digital line with an unknown data format and protocol, would be with a lightly coupled audio monitor. Digital data bursts will be obvious as noise, total silence will imply no activity because of no supply power. THAT would be my suggestion. This is a scheme similar to that used for sensing abandoned computer wiring in large rental space office buildings.

Easy to say, tricky to implement and test remotely with no test equipment. To transmit colour images to several stations from a few remotes would require bus speeds of several Mbps. Given this is almost certainly going to be a twisted pair, EM coupling will be difficult especially if the signal is shaped to minimise EMI, so that leaves direct capacitive coupling at a terminal. You can bet the first service engineer that turns up and see's evidence of tampering will hit the roof... If they haven't detected it beforehand .. we have no way of knowing if the system monitors SNR etc over time...

 

Hello,
Both Bus/bus connectors are connected each with twister pair - ie two wires.

 

Hello,
Both Bus/bus connectors are connected each with twister pair - ie two wires.

OK, and unshielded twisted pair cable does not seem like it would be carrying fast video, if it were common style twisted pair..

 

OK, and unshielded twisted pair cable does not seem like it would be carrying fast video, if it were common style twisted pair..

CAT5 cable is unshielded twisted pair and is good for 10Mbps over surprisingly long distances. BT, Virgin and other run multi-Mbps signalling for broadband services over unshielded TP for years, much of which is some pretty old rubbish cabling. I get 385Mbps with a 3% error rate broadband over copper from the exchange about 1.2km away. As an aside, VM were outside this am pulling fibre to the home, in a few weeks I'll be upgraded to 500Mbps over fibre and 1 or 10Gbps if I want to pay a little/lot more.

 

CAT5 cable is unshielded twisted pair and is good for 10Mbps over surprisingly long distances. BT, Virgin and other run multi-Mbps signalling for broadband services over unshielded TP for years, much of which is some pretty old rubbish cabling. I get 385Mbps with a 3% error rate broadband over copper from the exchange about 1.2km away. As an aside, VM were outside this am pulling fibre to the home, in a few weeks I'll be upgraded to 500Mbps over fibre and 1 or 10Gbps if I want to pay a little/lot more.

OK,Irving makes a valid point. My error! BUT CAT5 is certainly a very special case of STP cable. We need a more detailed description of what the TS is actually dealing with. Otherwise there is guessing .

 

@MisterBill2 what details are on your mind? thx

 

There seems to be no power feed in that connector. Is there another connector?

Why don’t you post a link to the entire manual you quoted? You had us believing before that there were only two wires connected. That led to false inferences. And we still don’t have the whole story.

 

hello
these is all what is there.

https://forum.allaboutcircuits.com/threads/how-to-sense-small-current-on-dc-line.208608/post-2008244

that one is in my flat
https://www.golmar.es/products/art-4-g2-plus

and attached photo how it is connected

 

And there are no other connections?

Interesting. I don’t see where power is coming from. I guess it has to be the bus lines, if there is no other connection.

 

@BobTPH @MisterBill2 G2+ protocol appears to be a proprietary 2-wire multidrop power and communications bus for linking various security cameras, video feeds and alarm equipment together, similar to RS485 or CANBus, featuring 30v DC power-over-line and differential signalling, with 75ohm end-of line (EoL) termination.

As you can see from the above picture, it uses normal phone-line style twisted pair. What is surprising is the fact that there are two pairs here, which would imply this is not the EoL, yet the termination resistor is enabled. The 'normal' characteristic impedance of a phone-line twisted pair is around 150ohms, so it may be they run two pairs in parallel for resilience or, maybe, to reduce line resistance to minimise the voltage drop from the source node.

 

Hello,
i have doorbell which is connected on some main / central wire (communication bus non-polarized?). I measured the input and it shows 30V DC, as the cables are pretty thin i assume there will be low current.

Is it possible use some circuit that can send signal to some other circuit with a relay assuming if the doorbell is working there is (30V) the relay is on,
in case there is no electricity the relay gets disconnected.

I am not sure if such an module can be used with Jumber set to low volt. Ie not sure if signal can be from doorbell wire even the module will be powered by completely different 12V external PSU.

https://dratek.cz/docs/produkty/1/1927/1700475986s_1700646270s_1476828250s.pdf

Thanks

I think you can take a look at this Adjustable DC Current Sensor Switch. https://www.amazon.com/Adjustable-Current-Flameproof-Sensing-Normally/dp/B09NZ98X63

 

OK, the unknowing and uneducated here - - - but what's going on with SA and GND? Is there any kind of signal there? According to the posted document there should be 12V @ 50mA (MAX). Can you get any kind of reading there? If so - and again, "unknowing and uneducated" if there's power there should be something readable there. If power goes down - no power. No ? ? ? A simple LED showing an active circuit would indicate the system is live. If it goes down so would the LED. No LED, no power. But I'm speaking way over my head on this one. Only offering food for thought.

 

SA is a secondary output that, if I read it right, activates when the doorbell is pressed, to enable other sounders, lights, etc. for people with disabilities eg blind/deaf. Its normally off, so no use here.

 

no use here.

OK.
What about GND and any of the other lines? Can they be used without causing interferences?