I wanted to generate events when someone pressed my door bell. I looked around and couldn't find any Z-Wave enabled ring bells so I decided to buy this the LightwaveRF Secure LW2301 Plug-in Wireless Door Chime which I used with the RFXCOM plugin and the RFXCOM USB Transceiver. Setup was easy and it worked OK with Indigo but the ringer base kept ignoring the remote chime every time the mains went off at my home so I had to power off/on the unit again to "re-sync" it which was very annoying. Eventually I hooked it to my computer UPS to avoid that problem but it shouldn't really do like that. But what made this unit useless is that with some months of use the remote chime push button became unreliable and eventually it wouldn't work even if you pushed really hard. Clearly not well made so I decided to avoid buying the same crappy door chime again.
I looked again for Z-Wave enabled ring bells but stillcouldn't find any. I found this article in Vesternet which showed how to convert an old school 6V wired bell chime using a relay and a Fibaro Door/Window module. This looked interesting but I wanted to integrate with a more fancy door bell. I then found this post which got very close to what I wanted to do. There were a couple of things that I didn't like though. The post used a battery powered door bell and I wanted a mains powered one. On the other side the circuit shown on that post connects the Fibaro Door/Window sensor with the door bell into a single circuit connecting both batteries. I checked with someone who knows about electronics and he said this could lead to the battery getting discharged faster.
I went on to research how I could Z-Wave enable a standard door bell. Using the idea from the second post I bought this £12.99 wireless door bell unit which has an LED on both the push button and the base. Taking the idea from the Vesternet post I tried to find a relay that could be activated when the bell rang and the LED flashed but unfortunately the LEDs on this unit work a very low voltage (<1v) so I couldn't find relays for such low voltage. I checked again with my friend and he suggested using an optocoupler. This is basically a relay that gets activated by light. They can be very sensitive and best of things you can keep the the two circuits separate which makes it a lot safer. I found a cheap optocoupler in Amazon UK for less than £ 3 which had the right specifications. The final piece was a DIP8 to SOP* adapter pcb (like this one) which I bought off eBay for less than £ 2. So in similar fashion to the above posts I connected the optocoupler to the LED of the push button unit and then the output of the optocoupler to the sensor of the Fibaro Door/Window sensor. Here is a video showing how it works. Below there are some pictures showing the connections in the push button unit. The red and blue cables are connected to the anode and a cathode of the push button LED. The two white cables go to the Fibaro Door/Window sensor. The events trigger almost immediately and it's extremely reliable so I am very happy with the solution. Should I need to replace the bell unit again I can either buy the same ringer again or any other ringer which has an LED incorporated.
With this idea you can make any LED in any device in your house Z-Wave enabled!