Help me hack my DoorPhone system

[robolo]

I have a doorphone system setup for my front doorbell. There is a remote door unit which includes the pushbutton as well as speaker/mic. When the button is pushed the main doorphone unit rings the house telephones and you can pick up any telephone to converse with the person at the door. It also has call waiting feature so if you are talking to someone at the front door and the phone rings you will hear it and similarly if you are on the phone and the doorbell rings you can hear that as well through the handpiece.

It accomplishes this by having the phone line from the house demarc enter the main doorphone unit first and then go to the rest of the house telephone distribution.

Now here is my problem, my wife hates the distinctive ring of the doorphone. We have the system connected to our ELK so when the doorbell rings we get a nice Westminster chime sound through all the speakers. What I want to do is silence the phone ringing signal but still open the phone line for communication to the front door. In other words notification that someone is at the door would be by the existing ELK chimes but you could still pick up the phone to communicate when the doorbell rings. Basically it requires eliminating the ring signal generated from the main doorphone unit.

I was all ready to place a diode bridge across the outgoing doorphone phone lines but then I realized that there was no way to do this externally without blocking ring signal for all telephone calls. Remember the phone line goes through this device prior to distribution throughout the house.

I have some photos of the circuit board attached. I am willing and able to connect up a diode bride to the existing circuit or cannibalize it any other way that someone could recommend. I was also wondering if that large capacitor might be somehow involved in generating the higher voltage for the ring signal.

If you are wondering....I did contact the manufacturer who was not interested in helping me and advised that disabling the ring signal was not possible. Also the unit is now a few years old and the warrantee is expired so i am not worried about voiding anything

I have my soldering iron ready.......

 

[robolo]

Top of circuit board

 

[robolo]

Middle of circuit board

 

[robolo]

bottom of circuit board

 

[CollinR]

I was all ready to place a diode bridge across the outgoing doorphone phone lines but then I realized that there was no way to do this externally without blocking ring signal for all telephone calls. Remember the phone line goes through this device prior to distribution throughout the house.

I dunno if you have thought about this but it should actually go demarc>alarm>doorphone>handsets. Otherwise all you have to do is hit the doorphone button to bypass the alarm comms.

I can't help much on your problem though, I'll think about it some.

 

[robolo]

What was the brand of the doorphone?

It is Quantometrix

What cadence (ring pattern) does the doorphone use that you hate?

The cadance is not the issue. Just the fact it is ringing is a pain since we now have an alternative announcement. The phone will continue to ring for about 60 seconds if not picked up. We do not like the ringing going on when you know who is at the door and just want to open it.

What switches/settings/options are available on the doorphone unit?

Just on/off. No other options on the unit. There is a doorbell out contact that I am using to trigger the ELK.

Maybe you can modify device by finding where the ring generator is fed to the phones to make them ring. If you can cut this connection the audio functions should still work OK and outside calls will continue to ring.

That is exactly what I am asked for help with. Hopefully the pictures will allow someone to identify where the ring generator is located. I'm wondering if the big capacitor by the transformer might be associated with the generation of ring voltage spike but I don't know.

You would then need to find a different way to trigger the Elk, either with a a set of contacts from the door controller (if it has one) or by using the ring generator to trigger a relay designed to operate from telephone ring voltage.

Not a problem as the unit has a doorbell contact that I am currently using to trigger the ELK chime

*** Also Collin is correct that the wiring should hit the alarm panel RJ31 before going to the Doorphone unit.

I actually do have it set up that way just didn't include that bit of information. Sorry for the confusion.

Thanks for the help
Robert

 

[upstatemike]

I tried to edit my other post with an idea but the formatting wouldn't come out right and I had to delete it. Is the big transformer part of the power supply or is it actually creating a 20Hz ring voltage to ring the phones?

Maybe trace to where a double pole relay is switching the house phones from the phone line to the door box audio circuit. Then look for a place where a 20Hz ring voltage might be inserted, perhaps coupled through a capaitor. If you can figure out where the ring voltage comes from, the circuit can be disables or disconnected without disrupting the voice circuit.

Another idea would be to put a discriminating ring box on the line that directs the output of the door unit based on the ring pattern. (Often used with fax machines). Could be tricky to make sure the door audio still gets to the phones after the ring has been switched though.

 

[robolo]

I tried to edit my other post with an idea but the formatting wouldn't come out right and I had to delete it. Is the big transformer part of the power supply or is it actually creating a 20Hz ring voltage to ring the phones?

Mike,
I think the transformer is for the power supply because the unit takes 120v input.

 

[upstatemike]

Does the doorbell contact on the unit operate in sync with the ringing it generates for the phones? I'm thinking a circuit that shunts the ring voltage but only while the doorbel contact is active... that way it won't affect the ringing voltage from the telco line.

 

[robolo]

Does the doorbell contact on the unit operate in sync with the ringing it generates for the phones? I'm thinking a circuit that shunts the ring voltage but only while the doorbel contact is active... that way it won't affect the ringing voltage from the telco line.

Yes it does.. every time the phone starts ringing the doorbell goes off.

I like the idea you are suggesting Mike. Are you thinking of a bridge diode circuit with a relay that is triggered by the doorbell? I think that would actually work very well. Can you help with designing the cirucit?

 

[upstatemike]

Does the doorbell contact on the unit operate in sync with the ringing it generates for the phones? I'm thinking a circuit that shunts the ring voltage but only while the doorbel contact is active... that way it won't affect the ringing voltage from the telco line.

Yes it does.. every time the phone starts ringing the doorbell goes off.

I like the idea you are suggesting Mike. Are you thinking of a bridge diode circuit with a relay that is triggered by the doorbell? I think that would actually work very well. Can you help with designing the cirucit?

I am not sure what you are referring to by "bridge diode" but I was thinking of using the relay to put a capacitor across the phone line. This would short out the AC ring voltage but not the DC talk voltage so it would kill the ring signal to the phones. Probably something around 10 microfarad at 100 working volts. Might need to put a small resistor in series with the capacitor to protect the ring generator on the doorphone unit although it probably already has some sort of protection against shorts on the wires to the phones.

 

[robolo]

Upstate,
This was what I was referring to as the diode circuit. I have these parts currently. Just not sure how I would trigger this with a relay. This was from www.hometoys.com web site

If you work odd hours, need to work uninterrupted, or just want to take a nap without being disturbed -- this is the gadget for you. This device ,wired in series to your phone line, will block the ring signal to all devices down-line. You don't have to go to each phone and turn off the ringer but you will still be able to make outgoing calls. Triggered by an appliance module, It gives you remote-control silence.

The silencer consists of a DPDT relay with a 120v coil and 4 1N4003 diodes wired as shown below. Attach an AC power cord to the relay coil and plug it into an appliance module. Turning the module on will silence phones and an answering machine will not "hear" the ring (I block the machine also because mine is very noisy and will wake me up). Phone connections are your choice. I used a modular plug and outlet because I'm an apartment dweller, but a homeowner could hardwire to a terminal block.

EDIT: Oh wait, I can use ELK to open and close a relay like they are showing above using the same rule that is now in place to initiate the door chime.

That would be a neat solution. I am only concerned that it may not open the relay quick enough to disable the start of the ring. I will have to put it together and see.