Smart doorbell done differently

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1

Noticed a number of projects to make your old-fashioned doorbell smart, but typically these use relais so when your component fails, your bell stops working alltogether. Therefore I took a different approach:

  • I am using a bell transformer which creates a 8V AC, when the knob is pressed, this will ring the bell
  • I take the 8V AC for the ringer - where this 8V will be there only when the bell is ringing. Then use a diode rectifier, a condensor, some resistors and a zener diode to transform this into a 3.3V pulse which is put on an ESP-01s on its Rx pin. Works flawlessly!

Below the scheme and the yaml.

doorbell-detector-schema-en
doorbell-detector-schema-en2968×1500 388 KB

esphome:
  name: doorbell-detector
  friendly_name: Doorbell

esp8266:
  board: esp01_1m   # adjust to your ESP-01S variant (e.g. esp01_1m or esp02)

# Wifi settings (use secrets.yaml, never hardcode passwords)
wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password

logger:
  # logger only transmits on TX, RX is not used by the logger
  # once GPIO3 below is declared as a gpio pin, it's free to use as a digital input

api:
  encryption:
    key: !secret api_encryption_key

ota:
  platform: esphome
  password: !secret ota_password

binary_sensor:
  - platform: gpio
    pin:
      number: GPIO3      # = RX pin, not a boot-strapping pin, safe to use after the one-time flash
      mode:
        input: true      # no internal pull-up/pulldown: R3 on the schematic already handles that
      inverted: false     # HIGH when the doorbell is pressed (as in this circuit)
    name: "Doorbell Pressed"   # ESPHome slugifies this into entity_id binary_sensor.doorbell_pressed
    id: doorbell_pressed        # internal ESPHome reference (for lambdas/automations within this yaml)
    device_class: sound            # gives an on/off display instead of open/closed
    filters:
      - delayed_on: 20ms   # small debounce margin (in addition to C2 on the schematic)
      - delayed_off: 50ms
    on_press:
      - logger.log: "Doorbell pressed!"

  - platform: status
    name: "Doorbell Connected"
    entity_category: diagnostic

sensor:
  - platform: wifi_signal
    name: "Doorbell WiFi Signal"
    update_interval: 60s
    entity_category: diagnostic

  - platform: uptime
    name: "Doorbell Uptime"
    update_interval: 60s
    entity_category: diagnostic

text_sensor:
  - platform: wifi_info
    ip_address:
      name: "Doorbell IP Address"
      entity_category: diagnostic
    ssid:
      name: "Doorbell WiFi SSID"
      entity_category: diagnostic

  - platform: version
    name: "Doorbell ESPHome Version"
    entity_category: diagnostic
2

Post a picture of the device please.

3

While an esp-01s is cheap and may be considered disposable, I would feel better with using an optocoupler (pc814/ pc817, with a resistor (~330 Ohm for 8 VAC) matching your input voltage (and maybe a diode, e.g. 1n4148) here.

But, there are many ways to skin a cat (I used a zigbee based water sensor (running from batteries for over two years already) as dry contact with a reed contact tacked to the traditional bell/ gong coil - why, because the location around the bell doesn’t easily give me an option to power an esp8266/ esp8285), your approach will work as well.

4

In my setup I have the optocoupler replacing the reed switch of a 433mhz if a battery operated door sensor. So far 18 months on AAA. Couldnt get reed to work reliably with the coil.

5

Here is a picture of the device.

IMG3962
IMG39621920×2560 944 KB

I also looked at the optocoupler option, but since the transformer is a safe device, that is not really necessary. And with the zener diode the voltage on the ESP will always be 3.3V, so this will not ruin the ESP..

6

Why not using a AC relay parallel to the ringer?

7

Using an AC relay paralel to the ringer sounds like shooting a mosquito with a cannon to me…

8

There are also little mosquito cannons :wink: