ELK 930 and SkybellHD

[automan7832]

I have a bit of a unique situation that has me pulling my hair out. I have a Skybell HD video doorbell that I need to trigger an ELK 930 in order for a Euro Style chime to be activated. The chime itself is very simple, the 16v line connects to terminals to power the device, then a doorbell is wired in-series on two separate terminals. When the door-bell button loop is closed, it completes the circuit and the bell rings. However, I am unable to wire the doorbell like you normally would through the chime terminals due to the Skybell needing constant power which makes the chime constantly ring. The goal is to have the Skybell powered by the transformer through the 930 terminals, and when pressed, the 930 will close its' contact thus triggering the chime. The problem is, the Skybell doesn't create the 900ma trigger to activate the 930. I am have had this issue in a few customers homes since these chimes seem to be becoming more popular. 
 
 
Any suggestions? I figure you could use a resistor to help increase the Skybell current draw but I am getting a little out of my depth...
 
 
The chime being used is a Zamel DNT-222

 

[RAL]

The 930 senses current flow, but isn't meant to create a load that draws current by itself.  I think you've figured that part out.
 
What you need is a resistor that replaces the load that the chime would normally create - something that will draw a bit over 900mA.
 
Assuming you have a 16V transformer,  a 15 ohm resistor should do the trick.  Just wire it in series with the transformer, Skybell and 930, as if the resistor were the chime.
 
To be on the safe side, you should use a high power resistor of 25W or more. Should the doorbell ever get stuck in the "on"position, it's going to generate a good amount of heat.  A smaller wattage resistor would burn out.
 
https://www.amazon.com/dp/B015Z18EO2
 
How do you plan on having the 930 trigger the Zamell chime?  The 930 has an open collector output, which may not be compatible with the chime.  I don't know what the chime's input circuitry looks like, but to be safe, you could use the 930 to trigger an Elk 924 relay, which in turn could activate the chime.

 

[automan7832]

Correct, I am using 16V to power everything. I gave it another go with the exact resistor you mentioned (happened to have a big pack of them) and no dice. 
 
My thought was to use the open collector input to close the doorbell terminal on the back of the chime, thus causing it to ring. This electronics on the chime are pretty simple....power in, then the button terminal completes the circuit. When I short the open collector input, the chime rings so perhaps it's not staying shorted long enough. 
 
How would you suggest I wire the 924 in conjunction with the 930?

 

[RAL]

If the Zarnell chime runs on 16VAC, it may not be happy with an open collector output trying to drive its input.  The open collector output only passes DC current, and not AC.
 
The Elk 924 relay needs 12VDC to power it, so you'll need a 12VDC wall wart, unless you already have 12VDC available elsewhere.  The 924 doesn't draw much current, so any wall wart that can deliver 100mA or more will do. 
 
The 930 output pulls to ground when the doorbell button is pressed.  So the circuit requires a pullup resistor to hold the output high.  This gets connected to the -T input of the 924 so that the relay will close when the 930's output goes low.   The value of the pullup resistor isn't too critical.   It needs to be greater than 500 ohms, and can be as large as 2400 ohms.   Current is low, so a 1/4W resistor should be fine.
 
Here's a diagram of how to hook it up.

 

[automan7832]

Am I supposed to wire the skybell in-series with the same resistor as before correct? I tried the way that you described with the skybell wired in-series, as before, and it was constantly ringing the chime. Any ideas as to what I'm doing wrong? I even played around with different resistors a bit and had the same issue. 
 
Also, the Zamel chime accepts 16vAC, then converts it to dc so the chime motor and door bell button contacts are all DC. With that in mind, I would think that simply wiring everything per your first response would work...especially since shorting the "out and neg" causes the Zamel chime to ring. Am I on the wrong train of thought there? It's almost like it's just not drawing enough current to trigger the 930...
 
Thanks for all your help. 

 

[RAL]

Here's a  more complete diagram of what I envisioned.  I've shown two AC transformers, one for the Skybell and one for the actual chime.  I don't know how much power your chime requires in terms of Volt-Amps, but it's possible that between the load resistor on the Elk 930 input, and the chime itself, that a small transformer would be overloaded.  The load resistor requires about 17VA.
 
If you have it wired this way, and it doesn't work, here are some things to check:
 
Make sure you have the 930 output connected to the -T (minus T) input on the 924 and not the +T input.
 
Make sure you're using the N/O output of the 924 to the chime, and not the N/C output.
 
If the chime is ringing constantly, disconnect the Skybell and see if the chime stops.  Then, short the two wires momentarily and see if the chime rings.  If so, then it would seem that the 930 and 924 are wired properly and working properly.  
 
My conclusion then would be that the Skybell draws more power when idle (i.e. when the button is not pressed) than the 930 can tolerate.  A way to deal with this might be to split the power path through two resistors, one that the 930 monitors, and a second one that bypasses the 930.  The trick will be figuring out if there are resistor values that will allow that to work.
 
Do you happen to have an AC clamp-on ammeter?  It would help to know how much current the Skybell draws.
 

 

[automan7832]

The clamp on reader reads .13amps being drawn when only the skybell is wired to the transformer

 

[RAL]

The clamp on reader reads .13amps being drawn when only the skybell is wired to the transformer

 
Ok, that's a good number to know.  It seems low enough that it shouldn't cause the 930 to trigger, since Elk claims it takes 900mA.
 
Did you try the other test I mentioned in my last post, of removing the Skybell and just testing things without it, as if you had a normal doorbell button in the circuit?  That would show whether everything else is working as it should.

 

[automan7832]

Sorry it's been so long since I've taken another crack at this. I really appreciate your help. 
 
I wired everything up again, per your diagram, and I no longer have the constant ringing issue and the skybell powers up as it should. . However, I can still not get the Skybell to trip the 930. With everything hooked up, I short the "out" and "neg" terminals on the 930 and everything works how it should. Does this mean that the resistor in series with the skybell is not large enough?

 

[RAL]

Sorry it's been so long since I've taken another crack at this. I really appreciate your help. 
 
I wired everything up again, per your diagram, and I no longer have the constant ringing issue and the skybell powers up as it should. . However, I can still not get the Skybell to trip the 930. With everything hooked up, I short the "out" and "neg" terminals on the 930 and everything works how it should. Does this mean that the resistor in series with the skybell is not large enough?

 
What happens if you disconnect the Skybell and short the wires together, as if it was just a plain old doorbell button that was being pressed?  With the 15 ohm resistor in there, that should cause the 930 to trip.  If the 930 doesn't trip when you do that, then something isn't right.  It would also be helpful if you can measure the voltage between the NEG and OUT terminals of the 930 when you short the doorbell button wires.

 

[automan7832]

Good news, the doorbell just worked successfully!!
 
When I initially hooked up all of these components I must have done something wrong because the 924 was tripping constantly. I was messing around with resistors of greater values and forgot to remove one of them from the setup when I tested it again last night. I just swapped the higher ohm resistor for the 15 ohm one and it worked like a charm!
 
Now, my question is...do I need to place all of these components in a box or can they sit in the wall cavity by themselves? The wall cavity is uninsulated. 

 

[RAL]

Glad you got it working!  
 
I would put the components in a project box of some sort, rather than just let them dangle in space (what we used to call a cloud circuit).  It would be best to locate the box in a place where it can be accessed easily, even if it mean running some extra wire, rather than leaving it in a wall cavity where no one knows it's there.  I'm not sure if placing it in the wall cavity would violate electrical code.

 

[automan7832]

I have another question for ya.
 
I have a similar install where this application has been necessary, however, the chime is a little different. There is not a separate transformer that powers the chime, but since connecting the chime to 12vDC engages the bell, I tried this exact same wiring but connected one of the chime wires to the 12vDC + terminal and ran the negative side through the COM terminal on the 924, then the N/O to the other wire of the bell. The issue I am having is, when I Press the doorbell button, the 924 buzzes and does not activate the chime. When I remove power to the chime, there is no buzz and the light on the 924 turns on momentarily like it is supposed to. Is there an issue with running power through the 924?

 

[RAL]

The fact that the 924 buzzes makes me think that it is not getting enough power to keep it engaged.  It will pull in initially, but then when the contacts on the 924 close to engage the chime, the 12VDC power supply can't deliver enough current to power both the relay and the chime, so it the 924 drops out, disconnecting the chime.  Once that happens, the relay can get enough power to close again, and the process repeats, creating the buzz.
 
Do you know what the specs are on the chime in terms of the acceptable voltage range and current?   Is this a mechanical chime, or an electronic one?   Often, you will find a power rating in terms of Volt-Amps (VA), such as 10VA.
 
The 12VDC wall wart should also have a power rating.  If you went with a 12V, 100mA wall wart as I mentioned in one of my earlier posts, that is probably much too small.  Even a 1A wall wart might not be enough, depending on the door chime. 
 
If you can find the power requirement for the chime, then we can figure out exactly what you need.

 

[automan7832]

The chime is mechanical. The chime that I am dealing with is very similar to this one: https://picclick.co.uk/Knight-And-Gibbons-London-Servants-Bell-Battery-Operated-153119952514.html
 
I'm not able to find a volt rating on the chime itself. The old power supply for the unit was a 10vdc driver that replaced the batteries. The "wall wart" that I am using is (https://www.altronix.com/products/smp3) on the 12vdc setting. You're right about the buzzing issue, after I utilized a seperate "wall wart" to power the chime only, no more buzzing issue.
 
There are two chime located about 50 feet from each other and all of the wiring goes into one of the chimes with an 18/6 wire connecting the two chimes. When I connect the chime directly into the altronix transformer, the closest bell chimes, but the one 50 feet away does not ( I can see the chime start to engage, but not enough to rock the bell).  Is this just because it is not providing enough amps? Is there a way to find out the electrical rating on the chime if it is not listed?