Elk 930 and Doorbell Transformer

[Superjer2000]

Quick question on something that has me stumped.

I bought an ELK-930 doorbell detector and had planned to wire it up directly to the transformer (Method 1 in the instructions). When looking for the doorbell transformer, I found one hanging off of an outlet by my fuse panel that looks like a regular doorbell transformer but when I tested it, I was getting around 27VAC.

I figured that it couldn't be the doorbell transformer as I was expecting ~16VAC but after looking everywhere else for the transformer, I disconnected one low voltage lead from the transformer and the doorbell went dead. So I found the transformer but as noted it is reading a higher voltage than I was expecting. AFTER A bit more research I realized that this transformer is a tri-mode with 8V, 16V and 24V options. The low voltage leads are connected to the two outer terminals which are for 24V.

The REALLY ODD thing though (bear in mind that I am not an electronics guy) is that when I tested the AC voltage at one of the chimes when the doorbell was being pressed, I read 16V.

So... The transformer in the basement that is powering the chimes reads 27V. When the doorbell button is activated the chime is receiving 16V. I am very confused.

1) The ELK-930 instructions indicate that 24V is the maximum input voltage. Any thoughts on if 27V will be too much?
2) Any ideas why there is a difference in voltage between the basement transformer and the voltage actually getting to the chimes?
3) I was thinking a bit more that it would be nice to have a separate notification for the front and back doors. As I don't have any way to run wire back to the panel from the main floor chime which is the most convenient place to get the front and backdoor doorbell wires, I thought that I could maybe use a wireless sensor that has two hardwire inputs (generally used for magnetic contacts). However, I recognize that the doorbell detector doesn't have a regular "open/"close" output but rather an "open collector output". I'm unsure if I can use that "open collector output" with the wire-terminals on my wireless sensor.

Thank you in advance for any help!

 

[BLH]

Many transformers are rated for a voltage at its loaded current. When the bell is not sounding the load is not there and the transformers output will be higher. When you ring the bell. The transformer is loaded and its voltage drops. So what you are seeing is normal.
 
The ELK930 gets it power to run from the Output Connection to the device it is controlling input circuit. I know mine gets it small power requirements from either a X10 Powerflash or Insteon I/OLincs. You may have to see if your sensors electronics can power the ELK930.
 
The Doorbell circuit uses the doorbells current to activate. At its minimum of 900 mA. The drop on the Input is around 2.43 volts.
I could not see the 24 volt rating in my ELK930 manual. Only thing I saw was the Output could be a maximum of 12 volts at 40mA and the bell current had to be 900mA or more. I don't think you will have any issues with the bell input side of the detector. The output you will have to try and also determine which of the sensors connections is the + side.

 

[pete_c]

Personally I don't think you will have any issues. 
 
Here I use the Elk 930 in combination with the Elk 960 debounce circuit for the doorbell stuff.
 
Thinking that they sell the Elk 930's in 3 packs. 
 
Such that if you purchased a second Elk 930 you could use it for a second and different zone connection on the Elk panel.  Method #2.
 

 

 
I have only one doorbell button.  I would suppose though that I would have to add a second debounce ELK 960 board for a second button.
 
This way though you could make the second  one wireless.  The issue though of debounce remains if you connect the switch to the panel directly unless the wireless switch has a built in debounce circuit.
 
I do still notice doorbell ringers doing a continous press of the doorbell button; but I do hear it inside with the debounce circuit.  I wonder if an outdoor auditory feedback mechanism would help.
 
I had this issue a few years back such that I did add the Elk 960 after the installation of the ELK 930.
 
The two entities (doorbell stuff) and ELK alarm panel stuff are autonomous from each other.  Power driving the two boards comes from the panel.
 
I left the doorbell in place here and upgraded the button to a round LED style button.  I did have some corrosion issues with the older doorbell button initially.  My AC transformer put out more than 16VAC but less than 24VAC. 
 
That said my two Elk Circuits work just fine talking to the Leviton HAI OPII panel.  Its been a few years now and I don't recall the AC transformer value.
 
Earlier issues here related to button debounce timing and event triggers on the panel.  I did notice a sort of contraction relating to fixing a doorbell.
 
IE: shutting off the power at the breaker makes it such that you cannot test the voltages of the the transformer / doorbell buttons live.  That said though you can check the continuity of the circuts while the power is off. 

 

[Superjer2000]

Thank you for the help.  I was unable to get the doorbell detector to work with my wireless transmitter so I settled for having it connected to the transformer in the basement.  So far everything is working great BUT I obviously cannot distinguish between the front door and back door doorbells.  It is VERY rare that the backdoor rings but if it does it is my kids so I would like to know.  I am going to see if I find the wires for the backdoor doorbell and re-route them directly to the Elk.  I would loose the doorbell light but I'm fine with that.
 
Pete_C - that is a VERY interesting solution on using the Elk 960.  Unfortunately, I don't have power at the doorbell chime to run something like that.  With regards to the "debounce" issue, I haven't noticed any problems.  I have a rule set up in my home automation system (Elve) that plays an MP3 file whenever the doorbell button is pressed.  If I hold the button down, the file still only plays once.  If I push it twice quickly the file just restarts.

 

[BraveSirRobbin]

Are you still using the doorbell unit with your system?  If so, you can use a standard door/window magnet sensor and mount it next to the coil that triggers the dinger.   A magnetic field is generated whenever the doorbell button is pressed.  This will provide a contact closure (although a quick one) that might trigger your wireless sensor. I got this idea over the HS forums (pic on a DS10a sensor installed near the coil).   I did this for my doorbell using a DS10a sensor.

 

[Superjer2000]

Are you still using the doorbell unit with your system?  If so, you can use a standard door/window magnet sensor and mount it next to the coil that triggers the dinger.   A magnetic field is generated whenever the doorbell button is pressed.  This will provide a contact closure (although a quick one) that might trigger your wireless sensor. I got this idea over the HS forums (pic on a DS10a sensor installed near the coil).   I did this for my doorbell using a DS10a sensor.

Hey! No sharing brilliant ideas after I already spent $50 on my elk 930!!

I am going to give that a shot. I still have my doorbell chimes up as they provide the draw for the elk930 although I took out the strike plates.