I don’t need my doorbell to recognize faces, archive every delivery driver’s bad day, or worse, ask me for a monthly subscription. I just need to know someone pressed it while I’m wearing headphones or if I’m out of the house. But replacing a perfectly functional doorbell with a Ring for that one feature felt overkill, not to mention it would pile on yet another subscription.

So I gave my cheap wired doorbell an ESP32, taught it to report rings to Home Assistant, and let an automation ping my phone. The bell still works exactly as before, with or without Wi-Fi, and nothing new is pointed at my front door.

Know which doorbell you own before you wire anything

Transformer or straight mains, and a shake test that tells you which

There are two major kinds of doorbells you’ll find in most homes. Some have a transformer that feeds the chime 16 to 24 volts, and others, like mine, run straight off 230V mains. The button at the door switches live power to the chime, and that’s the whole circuit. Based on what kind of doorbell you have, your approach and how the bell interfaces with the ESP32 is going to differ. A circuit copied from a low-voltage tutorial won’t just fail here, it’ll likely destroy the ESP32 and potentially anything touching it.

The simplest way to find out what bell you have is to just shake the box. If shaking it produces a faint ding, and holding the button gives a ding, a steady buzz, then a dong on release, you’ve got an electromechanical chime. The good news is that all you need is a 50 cent reed switch sensor to get your ESP32 to know when the bell is ringing. The bad news is that it’s going to take quite a bit of trial and error to figure out where to place it.

The no-wiring trick that sounded too good to work

A fifty-cent reed switch, a lot of button presses, and a one-centimeter reality check

A reed switch never touches the doorbell circuit itself. The coil’s electromagnetic field closes it, the ESP32 reads the closure, and the original wiring stays exactly as it was. I used a standard MC-38 door sensor, the kind sold by the dozen for alarm kits, and held it against every face of the casing while pressing the doorbell button. But that approach didn’t work.

Turns out, the circuit only has a range of about a centimeter. Door sensors are deliberately insensitive so a stray fridge magnet doesn’t trip an alarm, and a chime coil’s leakage field fades rather quickly through air and plastic. The trick only works if the reed sits against the coil itself, which means opening the box.

Opening a 230V box without becoming a cautionary tale

Breaker off, tester out, cover on before you test anything

Before you start taking apart your bell, it’s best to switch off the breaker, not just the button, and confirm both chime terminals are inactive with a tester. Then check that neither stays live with the button released. Plenty of homes switch neutral instead of live, leaving the chime permanently energized and teaching you a quick and painful lesson in working with AC power.

I placed the reed against the end of the coil’s bobbin, long side parallel to the plunger’s travel, clear of the terminals, plunger, and tone bars. Then I closed the casing, plugged it back in, and tested. Putting the cover back again before testing might seem cumbersome, but it’s how you keep a DIY project from turning into an obituary. You might need a few tries to get the placement right, so patience is key here.

Once it triggers reliably, glue it in place or use double-sided tape for secure attachment, and sleeve the thin sensor cables until they’re out of the bell’s enclosure. If any of this makes you uneasy, feel free to call an electrician.

One ring, not a hundred notifications

Filters, a cooldown, and an Android that keeps napping on your alerts

On the software side, ESPHome takes care of the firmware with just a few lines of basic YAML. All you need is a GPIO binary sensor with the internal pull-up enabled and inverted set to true, so a closed reed reads as on. Wire the reed between that GPIO and ground, power the board over USB, and adopt it in Home Assistant through the ESPHome integration.

One thing that matters a lot here is filtering. Because the coil runs on AC, its field collapses 100 times a second, and the reed chatters for as long as the button is held. Adding a short delayed_on filter ignores stray blips, and delayed_off holds the sensor on across the gaps, both of which ESPHome provides as standard binary sensor filters. I’d also recommend adding an automation cooldown so an impatient visitor triggers one alert, not a dozen.

An automation triggered when the sensor turns on sends a notification to my phone through the Home Assistant Companion app. On Android, check the notification channel’s priority, or battery optimization might sit on your alert while the phone idles. Also, if you’re outside or otherwise not connected to your home network, you’ll have to have remote access to your Home Assistant via something like Home Assistant Cloud, Tailscale, or other remote access solution.

A dumb doorbell with just enough smarts

Ring can keep its subscription and its cameras

My doorbell still doesn’t know who’s outside, can’t stream video, and has never once asked me to upgrade to a premium plan. And that’s the point. It does the one job it always did, plus the one it never had, and the chime keeps ringing, whether my Wi-Fi, Home Assistant server, or patience for YAML exist or not.

All it took was a cheap door sensor I already had lying around, an ESP32, and one slightly terrifying encounter inside a 230V box. Ring can keep its subscription and its cameras. I just needed to stop missing deliveries with my headphones on.