Smart Doorbell Setup with Elcom HT 802/803 and Shelly Uni

General
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Hey everyone, I wanted to share my recent experience setting up a smart doorbell system in my apartment. It’s been a fun project, and I hope my journey can help others who might be tackling a similar setup!

I live in a multi-family home, and my doorbell system is an Elcom HT 802/803. Since I’m renting, I wanted to keep the installation as non-invasive as possible. After some research, I decided to use a Shelly Uni to integrate the doorbell into my smart home ecosystem. The goal was to trigger a HomeKit event whenever someone rings the bell.

Here’s what I did:

  1. Understanding the Doorbell Wiring: I started by testing the doorbell’s wiring with a multimeter. I found that there was a constant voltage, which changed slightly when the button was pressed. This indicated that the doorbell system was active and ready for integration.

  2. Identifying the Right Cables: I discovered that the Anschlussklemmen 6.1/5.1 terminals were meant for external devices like a bell. I connected two wires (brown and white) to these terminals. Interestingly, when I measured the voltage, I found 0V in standby mode and 0.785V DC when the bell was pressed.

  3. Introducing the Shelly Uni: Since the Shelly Uni requires at least 2.2V DC to detect a signal, the 0.785V from the doorbell wasn’t enough. To solve this, I considered using a non-inverting operational amplifier to boost the voltage to 12V. This would allow the Shelly Uni to detect the signal reliably.

  4. Testing the Setup: I powered the operational amplifier with an external power supply to avoid drawing current directly from the doorbell system. This setup worked perfectly, and the Shelly Uni was able to detect the doorbell signal. I then integrated the Shelly Uni into my HomeKit setup, ensuring that a HomeKit event was triggered every time someone pressed the doorbell.

  5. Final Thoughts: This project was a great learning experience. It combined my knowledge of electronics with my interest in smart home automation. I’m happy with how everything turned out, and I’m excited to expand my smart home setup further!

If anyone has questions about this setup or suggestions for improvement, I’d love to hear from you. Happy tinkering! :rocket: