WARNING : Electricity can be lethal, this work should only be attempted by a licensed electrician
When building my house it never dawned on me that one day my humble doorbell would be anything more than that. The more I started tinkering with my house I realised that given my central cabling design that I would be able to leverage my door bell as another input to take action on. What I started with is nothing more than a standard 8V AC door bell, what I have now is far from it.
At the moment the press of my door bell in certain cases will
– Make the door bell ring (wow)
– Logs the event to a table in a MS SQL database
– Turn on lights in the portico (if it is night)
– Turn on lights leading to the door bell internally (if it is night)
– In the next 6-9 months (money/time pending) it will take your picture/video and attach it to an email.
Bill of Materials
– 1 x 2 AMP 240V AC –> 8V AC transformer ($35 AUD)
– 1 x AC powered door bell ($16 AUD)
– 1 x ELK930 door bell detector ($40 AUD for 3 units)
– 1 x Large electircal junction box ($30 AUD)
– 1 x 2m of 4 core cable (enough to go from the ELK930 to your automation system) ($2 AUD)
– 1 x 40m (enough for your door bell runs) of 2 core cable. ($10 AUD)
– 1 x HPM PE Cell ($60 AUD)
– 2 x Clispal 30PBL 240V push button switches ($26 AUD)
– 2 x X10 two way appliance modules ($75 AUD)
– 1 x 2m of multi core 240V AC cable ($2)
Total Cost = $296
– Soldering Iron
– Screw Driver
– Device to drive X10 modules and read open collector inputs. I am using CSI’s excellent HomeVision Pro
– Drill and drill bits (masonry may be required for brick)
– Pencil / Pen
– Various electrical connectors
Step 1: Run cables for the doorbell
Run adequate cable. All of my cables were run to a central location. This was key in enabling the door bell to be hooked in to my automation system. One cable needs to be ran from the door bell to the garage and another cable needs to be ran from the garage to the momentary switch. I used figure 8 cable as this will be suitable for the current of the door bell.
Step 2: Wire in the doorbell in to the ELK930
Wire in your door bell according to your manufacturers instructions. My wiring is as per below.
Wire in the momentary switches and the ELK930. The ELK930 is a module that pretty much sucks the voltage out of the line and provides an open collector to any alarm / automation system. Put simply it stops voltage being fed in to my Homevision Pro’s mainboard and allows the Homevision Pro to detect the door bell being rung with no voltage being fed in to the unit. This module has been great and very cost effective. It probably could have been replaced with a relay (single port double throw) but would be more expensive.
The door bell is wired in to the ELK930 and the ELK930 is wired in to one of the Homevisions Pro’s input ports.
At this stage the door bell will ring and the input will be pickd up by the Homevision
Step 3: Add in some smarts
Yes the HomeVision Pro knows about my door bell being pressed but it is not doing anything about it (other than flashing an LED). First lets just get it to log the event to a database
Now when the door bell gets pressed the Homevision Pro will call a VB script I wrote which logs the event to a SQL database and gives a timestamp.
So we know when the door bell rings but that’s about it. Le’ts make it even smarter
Step 4: Day or night?
Given we know when the door bell is rung we can now use this event to drive other events in the house. How about for starters turning lights on when the door bell is pressed and it is sufficiently dark outside. That sounds good but we don’t know if it is day or night at the moment. By adding in a photo electric cell we are able to deem day from night. I am using a HPM PE 170 to carry out this task. To simplify the tech talk it is a light sensitive switch. This unit will be used for many other decisions in and around the house. The problem with this HPM unit is that it switches 240V AC. If I fed 240V AC in to my Homevision Pro’s input port it probably wouldn’t end pretty (I would be crying), I need to somehow get rid of all the voltage and turn this in to an open collector input. A relay is what we need here. The 240V AC output from the PE cell will drive the relays coil and power the electromagnet which moves the contacts from NO (Normally Open) to NC (Normally Closed). I am using an Omron L2YN DPDT (Dual Pole Dual Throw) relay, it is an overkill but that is all my friendly electrical wholesaler had in stock on the day of my visit.
Implementing the HPM PE 170 is pretty simple. Find a suitable spot to mount, turn the power off to your power circuit. Run power to the HPM PE170, run the switched power to the coil side of the relay and run the NO/Common to a Homevision Pro’s input port.
There is not much logic to add to the Omron LY2N. The port on the Homevision Pro will either be high or low which represents day and night. I log the time of day and night to a SQL database (may push the data through at some stage to SQL Server Reporting Services to plot the data but it is not required).
Step 5: Add a splash of X10
The aim to integrate in lights requires a means to automatically to power them on and off. I am using X10 as the transport protocol. The Homevision Pro has a built in TW 523 interface that allows duplex X10 transmission. I am interfacing the TW523 with an XTB-IIR from JV Digital Engineering which in turn provides communication to all the X10 appliance modules in the house.
The light switches need to be replaced from the traditional rocker based switches which won’t cope with the automation turning on lights to either momentary or pushbutton switches. I have elected to use Clipsal button 30PBL switches. These switches have a nice blue LED in them. This provides us with a visual inidication to show if a light is on or off.
The challenge for wiring was space, 3 rocker switches were replaced with 3 Clipsal 30PBL’s which are much deeper plus we need to wire in two X10 appliance modules. The original electrician is looping the active in this instance at the switch. I did not change this.
What we began with
Power off working away
Complete, but what a mess, cables to be made safe
All back together with lighs on, tidy and safe
I have set addresses on the modules, we now need to add some logic to the Homevision Pro. The logic below is very straight forward. It simply states. If the door bell is pressed and it is night the two lights turn on for three minutes. Simple.
Now for a demo, for the purpose of this demo I have changed the timer to 1 minute.