Nest Hello - Doorbell Chime With Integrated Transformer UK (220-240V AC - 16V AC)




Introduction: Nest Hello - Doorbell Chime With Integrated Transformer UK (220-240V AC - 16V AC)

Hope my instructables save you some pain...

I wanted to install a Nest Hello doorbell at home, a gizmo that runs on 16V-24V AC. The standard doorbell chimes with integrated transformers currently available in the UK feed 8V to the doorbell push button, so are no good for Nest Hello.

After searching online in UK and European sites without success, I decided to make my own.

This instructable shows what I used and how I put it together, to help others that want to do the same.

DISCLAIMER: if you decide to follow these instructions, you do this at your own risk! Please be responsible and work with safety in mind!

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The Chime:

First thing to find was a wired door chime that works within the same voltage range as the Nest Hello and has enough space in the casing to fit the transformer and the Nest connector.

The only compatible chimes I could find in the UK are from the Friedland range by Honeywell, as they work in the 8V-16V AC range.

From the Friedland range that work with upto 16V~ power input, I chose the Freedland D117 Ding Dong chime by Honeywell (see photo). This can be powered by 4 "C" size batteries (so loads of free space in the case), or by an external transformer with outputs between 8V and 16V, has a modern, minimal and simple design, that would suit most homes, and the cover is flat, so maximises inside space. Funny enough, the inside of the chime looks identical to the one shown on the official Nest Hello installation video, so probably a good choice.

I bought mine on Amazon, that had the lowest price I could find.


The transformer:

As Maplin is no longer around (big loss), the obvious choice was to search online for a 240V AC to 16V AC transformer. After looking for a while, I found a generic plugin one on ebay that seemed to fit the requirements (see second photo) and was posted as compatible with Freedland chimes and Nest Hello (link).

In case the posting is gone when you read this, the ebay seller was tssukcom , their ebay shop is called EZ Security Solutions (link) and the posting title was 16V AC Transformer UK 3 Pin Plug (Nest/Friedland Compatible)


Tools and other stuff:

You will also need:

  • A normal black pencil
  • Some bits of mains wire (I only used one brown and one blue bit about 15 cm long
  • Some small wire connectors (see photos) - the ones I got came on a strip of 12. I only used 3, as I soldered together some of the wire joints (more compact than connectors)
  • Insulating heat-shrink tubing or insulating tape
  • Wire-cutting pliers
  • Screwdrivers (one medium flat one, one small flat one, and one phillips)
  • A dremmel tool with a small cutting disk - ALTERNATIVE: you could also use a stanley knife(harder work)
  • A soldering iron - ALTERNATIVE: more small wire connectors
  • Thin cable ties (I used 3, worth having some more just in case)


Step 3: Getting Rid of the Transformer Case & Extending Wires

For the transformer to fit in the chime case, I had to get rid of the plug-in plastick box it came in. This needs to be done with care, to avoid damaging the internal bits you will use.


The transformer plastic casing is welded shut, so I decided to chop it open. I used the dremmel tool with the slim cutting disk (second photo) and cut through the plastic weld on all 4 corners. I then slipped the medium size flat screwdriver in the gap I just cut and twisted it to split the case open (be gentle). Idid this on all 4 sides.


I then checked which wire was connected to the neutral terminal of the plug, cut it as close to the terminal as possible using the pliers, and marked it as N (as both input wires on the transformer are blue). Then I cut the wire connected to the other terminal and freed the transformer from the case. See third & fourth photos showing the resulting item.

I then soldered the short strip of mains blue wire to the neutral wire in the transformer and soldered the short strip of mains brown mains wire to the other input wire on the transformer . You can use connectors instead of soldering, but be conscious that this will be bulkier and you will be adding more stuff to fit in the (tight) chime casing.

I then insulated the soldered joints with heat shrink tubing (you can use insulating tape instead).

For now, leave the free ends of the blue/brown mains cables with no connectors.

I then cut the transformer output cables (black / black with white line) as close to the plastic piece that prevents the cable from braking when going into the plugin black transformer case.

I then separated them and added an extension using a bit of the same cable, roughly 15cm long. I again soldered the joint and insulated it with heat shrink tubing. Doing that should hopefully give you enough flexibility to connect them to the chime and/or the cables coming from the door bell push button to suit your home's set up. You can chop any excess when connecting the chime for testing.

Step 4: Preparing the Chime Casing

Pull open the chime cover. the second photo shows what you'll see.

ATTENTION: While you work in the chime, try not to mess up the bells (the 2 metal strips on the sides, that make the ding dong noise when hit) or their mountings.

Pull out the battery connectors from both battery compartments, as you won't need them when the transformer is installed (see second and third photos).

Note that the chime is upside down on all pictures.

Place the transformer in the battery compartment of the chime case that has the big round hole, with the cables pointing to the outside edge of the case (see fourth photo).

Make sure that the transformer metal core is inside the 4 slots shown in the second photo and that there is some plastic left between the slots and the metal core.

With the pencil, trace around the metal core of the transformer, drawing it's shape on the chime case.

Step 5: Attaching the Transformer

Using the dremmel tool, cut a hole on the chime case following the pencil line. STAY AWAY FROM THE 4 SLOTS! (see 1st photo)

Test fit the transformer and fine tune the hole if necessary until the metal core fits in it. You may need to trim some plastic protrusions on the case to make the transformer sit flush over the chime case bottom.

Feed the cable tie through one of the slots from the back of the case over the metal core and back into other slot, attach on the back of the case (lot's of space there, not enough in the front).

Repeat on the other side. (see third photo for reference).

Tie the 2cable ties with a third one, to avoid them coming off the sides. Make sure the square joint is above the core, or the cover won't close. This cable tie can be loose (just keeps the others in place). See fourth photo for reference.

Step 6: Test the Chime

Note on first photo that I have fed the mains brown and blue cables to the back of the case through the oval hole. I also attahecd cable connectors on the ends of them (second photo).

Note on the first photo that the transformer output cables run upwards one on each side of the transformer.

Cut the mains power, and replace your previous chime with this one. Connect it to mains using the other end of the cable connectors (brown wire to brown wire and blue wire to blue wire).

Feed the cables coming from the door bell push button from the back to the front of the chime case, using the most convenient hole for your home's cable set up.

Connect the transformer output and the cables from the push button as per the circuit on the third photo (2-cable connection to the F and T connectors on the chime, the circuit diagram is a photo of the back of the chime retail box).

Switch on the mains.

NOTE: If the transformer hums loudly, one of your connections is not tight enough or clean enough. Cut off the mains and check all connections. Repeat until the transformer is quiet when powered.

Test the chime with the push button.

If it works normally (ding dong), you are ready to install your Nest Hello. Follow the isntructions on the Nest Hello app (not the ones in the video), selecting the version for a 2 wire connection.

If after installing and powering the Nest Hello the transformer hums loudly, one of your connections is not tight enough or clean enough. Cut off the mains and check all connections. Repeat until the transformer is quiet when powered (in my case it was the cablesconnected to the Nest Hello that were causing the humming - I had to clip a bit the wires that conecct to the Nest Hello and peel a fresh bit of wire for the connection, to stop the humming).

Hope this is helpful - GOOD LUCK!

Step 7: My Final Photos

The above photos show the working finished product in my home, after installing the Nest Hello.

They are for illustration purposes only, as your home's push button wiring set up may be different from mine.

If you are connecting the chime on it's own (i.e. no Nest components) as per the wiring diagram on the prior step, and works ok when testing it, then install the Nest Hello following the instructions in the Nest app (the ones AFTER the video) for a 2 wire installation.

As you can see, the nest wireless conector (round white bit at the top) fits snuggly in the other battery compartment, and the cover snaps on with no issues, covering everything.

Final set up is all tidily contained in the chime case.

Good louck with yours!




NOTE THAT THE CHIME IS FITTED TO THE WALL UPSIDE DOWN USING THE SLOTTED HOLES (had no choice, as the transformer is on the way of the regular fitting screw holes), AND THE CHIME TERMINALS ARE HENCE ALSO UPSIDE DOWN. I had to trim some plastic on the side of the slotted holes for the screws to fit flush.

1 Person Made This Project!


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15 Discussions


Question 18 days ago


I am trying to connect the wires the doorbell itself works and sends notifications to my phone but I just can't make the bell ring.
When I look at these photos I also don't see how the cables run, and with the scheme i also tried but remains the same.
Can some assist me, or tell me where i find the video :-)


Reply 3 months ago

Glad it was useful!


6 months ago

Hi All,

I wanted to give an update. I had been using my setup without issues for around 6-8 months. The Chime box when touched was always warm where the transformer was based and also where the Chime Connector was, but there were not any issues.

Then one day, I came home after a morning out, and returned to the Chime box making a horrible loud buzzing sound. I smelt burning, could see some smoke and when I touched the Chime box, it was VERY HOT and had melted somewhat.

Obviously I immediately isolated the circuit / turned is off; disconnected all the wires. Upon professional advice from a Nest Engineer and also a separate Qualified Electrician, I came to learn that with my setup, there was always a high risk of malfunction. The root cause of the issue was that the transformer was not a recommended transformer (recommended on the Nest site), which most probably caused the Chime Connector to malfunction.

I have young kids, therefore I cannot take any risks; this could have happened whilst we were sleeping. I have since got a recommended transformer (recommended on the Nest site), and Transformer housing, then had it fitted professionally. The Transformer doesn't look ideal outside of the chime box, but not as bad as I thought it'd look either. At least I can now sleep at night knowing it's fitted professionally.

All the best in however you decide to fit, but had to tell my story so you have all the details before making your own choice.



Reply 6 months ago

I am sorry to hear you had problems with your set up, and I fully endorse your recommendation for safety. One year after installation, my hardware is still going strong with no issues. I fully endorse your recommendation for safety.
With regards to what you have been told with regards to "recommended" transformers, as far as I can tell, there were never any transformer or chime models recommended on the Nest website, at least for UK customers. Be careful on what people that charge you to install what is sold as a DYI set up product, as they are likely to try to protect their business. The Nest Hello doorbell was obviously developed for US standards, and launched in UK without taking into consideration the much lower voltage output of all chimes with integrated bells sold in the UK, and the difficulty of finding a chime that works with their doorbell voltage working range.
The Nest website has been decommissioned a couple of months ago, and moved into the Google Store, site that no longer provides a quick link to support on Nest products, making it even more difficult to find any support or recommendations from what is now called "Google Nest", and in which I still can see no recommended transformers or chimes.
The Nest customer support is near non-existent, or at least was until a couple of months ago, when I gave up trying to get some answers from them on Nest Hello issues on the Nest App for IOS.
Because of the lack of support from their side, I no longer recommend this doorbell to friends - I point them to Ring instead.
Hopefully Google will improve Nest customer support, as part of their recent push to further integrate Nest products to their main hardware offering, but so far I have seen no improvement on customer support, just integration of the Nest hardware sales into their store.


11 months ago

I followed these instructions and have got so far but am now stuck. I’m hoping someone can make a suggestion that might help me move forward. Forgetting the nest component for the time being. I have the transformer connected to 240v on one side and the other wires going to button and chime. So still a simple normal doorbell circuit. The transformer is silent and all connections clean and tight. When the button is pushed the door bell chimes :-) However during the button pushing process under the noise of the door chime there is a horrible loud bussing noise coming from the chime itself.. its more of a buzz / rattle than a hum. When the button is let go everything is fine. The noise is only present when power is flowing to the chime.

I’ve tried cutting the push button out the loop and wired the transformer into F and T directly and used turning the fuse board on / off in the house to activate the circuit. I get the same noise.. please has anyone got any thoughts to help me along?


Reply 8 months ago

This sounds similar to what I have, all wired up fine with no buzz or hum but when the doorbell is pressed it isn't a ding dong but a dinggggg dong. It's as if the solenoid (or whatever it's called) is vibrating against one side of the chime rather than a single strike, only affects one side of the chime so it's as if it vibrates on 'ding' then hits the 'dong' as expected. Everything works fine other than this and has done for months now.


Question 1 year ago on Introduction

Brilliant post, I'm glad I came across it. I have a question for you - after some time using your setup, have you had any issues or concerns with how it all works? For example, have there been any outages? Does the transformer make a humming noise? Does the transformer get hot?

If you had to do it again, would you use the same approach or do something else?

I think these answers would really help me, and hopefully others who read your post too.


Reply 11 months ago

All still works well. I like the clean look of integrated transformer, instead of having another box on the side. If there is still not a chime with an integrated 16V transformer out there, I'd do the same.


Reply 1 year ago

All still working, no issues. There are no chimes with integrated transformers at that voltage yet, and can get no recommendations from Nest, so would probably do the same...


Question 12 months ago on Introduction


I really appreciate you making the time to post this advice!

Do you think this transformer will work? with the Nest Hello. I'm not sure about the dimensions.


Reply 12 months ago

Looks like output is 12V... so unfortunately not good.

Nest Hello needs 16 to 24V AC


1 year ago

I would not be encouraging non-professionals to play around with the internals of a transformer - one crossed or un-insulated wire and you could risk electrocution or fire.
Just keep the transformer external to the doorbell. For my install I drilled a hole through the wall to my garage to so the transformer could be kept out of sight.
FYI, I first wired my doorbell without the Nest the same as the diagram on the right in this attached picture.

then followed the Nest App instructions for a two wire install (even though there are three terminals connected). This re-routes the wires on terminals F and T through the supplied Nest adaptor. This seems to be working well for me.


Question 1 year ago on Step 4

great instructions

I used a separate transformer

not clear on your final picture how you wired

I followed the instructions that came with the ding dong

wired the nest hello to 0 and 1

Transformer to 1 and 3

all works, slight buzz - checked all connectors

But if I turn on chime in nest and activate, chime buzzes loudly afterwards and chime connector gets hot

How did you attach your wires?



Reply 1 year ago

There are 2 wiring schematics in the back of the box. I used the 2 wires to chime version ( see photo above), then followed the instructions for a 2 wired connection in the Nest app. The ones AFTER the video...