How to activate existing doorbell sound on knock?

I’d like to have my doorbell activated when someone knocks on the door. I figure it would be simple to add the SmartThings multi-sensor on the door. But what device can I wire into my existing doorbell to activate it? I don’t want it to be some other doorbell sound… I want it to actually activate my normal doorbell. Best place would be to wire it in by the sound box and not outside by the button. Is this possible?

I don’t know why it is that some people ignore the doorbell button and decide to knock instead. I want to hear the doorbell everytime.

I suppose it could get annoying if the multi-sensor sets off the doorbell every time I open the door. So perhaps some other ingenuity needs to also happen. Like if the sensor detected a double knock instead of a door slam as different events. Any ideas to actually make this happen only on a door knock and not when the door is unlocked and opened or slammed close?

I’ve moved this into projects because it has both a hardware and a software component.

The knock recognition should be easy to set up, it’s been done many times in the past. You trigger based on vibration detection. The problem is it’s not very reliable in some homes, it just depends on the architecture. At some locations, for example, a passing car vibrates the door enough to set it off. But you can certainly try that part.

The more complicated part is that your existing doorbell may be a momentary switch that completes your existing circuit. If it is that kind of doorbell, then there’s a physical break at that point, and you can’t trigger the chime unless the break is closed.

But there are other kinds of doorbells where the button itself won’t matter if you add a smart device to the chime, past the point where the button is connected.

And there are still others which already have a connection point on the chime To add a second buzzer, and those are very easy to work with.

It just depends on where the physical breaks in the circuit are and how they are wired. It’s possible that you will have to re-wire the existing doorbell button‘s connection to the existing chime in order to create a spot where you can add your secondary control.

So we will probably need pictures of the wiring that connects the button to the chime, and of the chime’s board. But I will leave that to the maker types in the community to discuss further.

For discussion of detecting the knock, just search the forums for “knock.“

So there are three separate parts to your project:

  1. selection and placement of the device to detect the knock

  2. selection and placement of a different device to allow the system to make your existing doorbell chime sound

  3. Setting up an automation to allow detection of the knock to trigger the chime

.1) will depend very much on your local architecture as far as how reliable it is.

.2) depends on how your current button is wired. Your project may require re-wiring the existing button’s connection to the chime. And it may be hard or easy. It just depends on the existing wiring.

.3) should be easy. :sunglasses:

I’m just tagging a few people who like this kind of project in case they have any ideas.

@ogiewon @johnconstantelo @anon36505037 @lmosenko @Darwin @jnewbury2280


Also, I forgot to ask: what country are you in and which version of the mobile app are you using (smartthings classic or “smartthings (Samsung connect)“) ?

You could also use a different method to detect the presence of a person at your front door, instead of “listening” or “feeling” for a knock. You could use a motion detector, for example. Or possible a beam sensor device. Or a smart doorbell. That way your doorbell could activate upon the approach of a person, versus waiting for them to knock or press the doorbell.

Personally, I have a Ring Doorbell at my front door. When a user walks up, the Ring sends a ‘motion’ event which is used to trigger an Amazon Alexa Routine (no SmartThings used at all!) The Alexa Routine then causes my Amazon Echo device to say “Someone is at the front door.” This allows us to know someone is coming before they press the doorbell or knock. You could also use the Ring Doorbell events within SmartThings, to cause an automation to run which could activate your existing doorbell, assuming it uses a simple dry contact closure (i.e. a button.)


I live in Florida. I have a 3rd Gen ST hub, but I use both new and classic apps on Android. I also have Lutron Pro 2 Bridge and Lutron switches/dimmers.

My doorbell is a Nutone KB-10 which uses a transformer that I think is between 12 and 24 volts AC. It has two chime hookups and I’m only using the Front door chime. The Rear door chime is single tone. I could wire something up to the Rear door chime which is not used. But because of how it works I think I could wire in parallel with the front door button…that way when either is triggered the Front door double chime is heard from the doorbell box.

This Nutone KB-10 seems to be a pretty popular doorbell to have. If you search for this model you’ll see pictures of it and it has a wiring diagram right on it when you take the decorative cover off. You’ll notice 3 hookups. Center hookup for the Transformer and then Right and Left hookups for the Front Door and Rear Door. All it takes is a split second button press to activate the chime. It doesn’t need to be held down. Actually holding it down is bad because the chime plunger gets stuck and then it doesn’t fully chime till you release.

I already have a Ring connected to my Front door (wired into my Nutone chime box). This way the Ring actually gets power from the Nutone transformer and it also rings my chime box. The idea of using Ring motion sensor is interesting as a trigger but often there are things that happen on motion which I would not want the doorbell to sound. I already have a SmartThings motion sensor at the front door to turn on the front door light on motion and I’ve noticed that critters turn the light on in the middle of the night (raccoons, possums, cats…etc). So I don’t want to do this project with a motion sensor. I much prefer the sensor be a knock sensor. I’ve tested the Samsung SmartThings multi-sensor (new version) and it works for detecting vibration on door knock when the sensor is on the inside of the door and you knock on the outside. So my door is good to pick up knocks.

In this project I see two challenges:

1 - What device to use to activate the momentary close circuit to activate the door chime box?

2 - Is the Samsung SmartThings Multi-sensor the right device to detect knocks or is there a better device that detects and discerns knocks versus just a vibration? Because I don’t want it to get triggered if I unlock the door and open it or if I slam the door close. There needs to be a way to discern a knock versus any other action. Perhaps cleaver programming can allow the simple multi-sensor to work.

Automation programming may be easy or maybe not. It all depends on how we detect knocks versus other activity. Maybe the solution is cleaver programming and/or additional sensors, or the solution is smarter knock sensor and then simple programming.

1 Like

This link has a pretty good explanation and pictures of the Nutone KB-10 and different wiring possibilities. Although they never seem to put two buttons in parallel as I suggested.

1 Like

If you have the Schlage BE469 lock installed, it has a special Alert mode with an adjustable sensitivity. With the highest level of sensitivity it can detect a knock on the door and chimes the lock (it’s got a loud chime / 85db siren built into it). The neat thing is that it only chimes when the locked is locked, so when you unlock the door to open it, it wont’ chime (which is what you had wanted).

The lock reports triggers over Z-Wave which can be captured by a DTH so it can be used to trigger other alarms, chimes etc, however if I remember correctly it only reports Tamper and Forced entry triggers and not the Alert triggers, so if you’re okay with the build in Chime it’ll meet your needs.