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  • Jun 13,2025
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Smart Doorbell Adapter – Module for Standard Wired Doorbells

Turn any wired doorbell into a smart Home Assistant trigger! This PCB uses a D1 Mini and optocoupler to detect the bell press directly from the existing transformer, no additional power needed. Fully isolated and ESPHome-ready—just wire it in and go.

Smart Doorbell Adapter – Module for Standard Wired Doorbells
 
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Tools, APP Software Used etc.

  • EspHome

    fenxiang

  • Home Assistant

    Open Source
    fenxiang

Story

This PCB allows you to convert a standard wired doorbell into a smart device using a D1 Mini (ESP8266) and an optocoupler, without requiring any additional power supply. The built-in bridge rectifier enables operation directly from the doorbell transformer’s AC output (~8 VAC). Once the doorbell is pressed, the module detects the signal and can trigger automations in Home Assistant via ESPHome.

 

📌 Highlights:

✅ No extra power required – uses existing doorbell transformer
✅ Safe signal isolation via optocoupler
✅ D1 Mini (ESP8266) compatible with ESPHome
✅ Compatible with most wired doorbells
✅ Easy installation – just connect transformer and bell wires
✅ Includes schematic and ESPHome config
✅ PCB layout tailored for seamless integration

 

 

📌Full build guide and source files here:

👉 https://smarthomeyourself.de/standard-klingel-smart-machen

 

 

Video


https://youtu.be/RVVDfOkP3Do

 

Code

  • ESPHome Code

    https://smarthomeyourself.de/hc_downloads/klingel_esphome.txt
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License: Attribution-NonCommercial-ShareAlike (CC BY-NC-SA)

Smart Doorbell Adapter – Module for Standard Wired Doorbells

Turn any wired doorbell into a smart Home Assistant trigger! This PCB uses a D1 Mini and optocoupler to detect the bell press directly from the existing transformer, no additional power needed. Fully isolated and ESPHome-ready—just wire it in and go.

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