DH905 16V 10VA wired doorbell transformer

What is a Wired Doorbell Transformer?

At a basic level, to understand the role a transformer plays, you simply need to look at the word itself "transformer."  When you have electricity coming into your home, it comes in at 120V.  This is too much voltage to power a simple device like a doorbell, as almost all of them function at 12V or 16V.  So what role does a transformer play?  It transforms the electricity from 120V to 12V, something your low-voltage door chime can handle.

To shop our collection or the most common wired door chime and wired doorbell chime transformers, please visit our doorbell transformer page.  This page features a small chart that details the basic features of each wired doorbell.  Please feel free to call or email us if you need help selecting the right wired doorbell transformer.

How Are they Used in Wired Doorbell Systems?

The typical system is wired like this:  The door chime low-voltage transformer is wired into your home electrical system.  Next, a wired doorbell push button is mounted beside the front door.  There is a bell wire that runs from that push button to the doorbell transformer.  Next, the wired doorbell itself is also wired to the doorbell transformer.  The circuit is closed, but when the front doorbell button is pushed, the electrical circuit is completed, and the doorbell chimes.


Most wired doorbells will use a doorbell transformer to power the system.  There are battery-powered wired doorbells that will use batteries, thus bypassing the need for a transformer, but these systems have some limitations.  Most notably, these types of doorbells (wired battery-powered) don't play well with lighted doorbell buttons because the power draw of the lighted button will quickly drain the batteries. In most cases, you will need a doorbell transformer IF you have or need a wired doorbell, especially if you have a lighted button outside.

There Are a Variety of Other Uses for Doorbell Transformers

A large variety of the products we carry at 1800doorbell.com are low-voltage types of products and operate at 12V.  For example, we carry 12V Strobe Lights that may be used to signal when charged or counters and tickers that work off of 12V.

Doorbell Transformers Play an Important Role with Extend a Chimes


A very popular category of products we carry are known as doorbell extenders, most under the brand name of "extend-a-chime."  These products allow you to extend the listening range of your wired doorbell system by looping into your wired doorbell, transmitting a wireless signal that stimulates a wireless door chime receiver to chime.


The critical element of these types of extenders is the wireless transmitter, such as the LRA-EX1000.  Using the supplied instructions, you simply wire this small transmitter into your existing doorbell transformer.  When the doorbell button is pushed, a wireless signal is created, along with your existing doorbell sound, which is received by an accompanying doorbell receiver.  This allows you to add wireless receivers, both plug-in and battery-operated versions are available, throughout your home.

One of our most popular products is the LH-3050WC which is designed for the hard of hearing who have an existing wired doorbell and have trouble hearing it.  In this kit, a doorbell extender transmitter wires into the user's existing wired doorbell transformer, so that a flashing doorbell receiver with strobe light is signaled.

I Can't Find My Doorbell Transformer - Where is Door Chime Transformers Located?

That's a tough question and there isn't a blanket answer.  It depends on where the electrician, who installed your wired doorbell, put it.  Over the years we have seen some seemingly random places doorbell transformers have been found. When you say "I can't find my doorbell transformer," it is usually, in one of three places.

  • In the garage - look around in the garage when you cannot find your wired doorbell transformer. There sometimes it is mounting near the garage door motor or recessed in a side wall near the circuit breaker box or electrical panel. If you see two wires coming out of the ceiling or wall, trace those wires to see if it leads you to your doorbell transformer.
  • In the attic - similar situation to the garage, sometimes the doorbell transformer is in the attack and mounted to a rafter. This in not very common but when people say I can't find my doorbell transformer and I've looked everywhere, the attic could be a hiding place.
  • In the wall near the wired doorbell - we've seem some situation when you can't find your transformer and it is located underneath the wired chime box (in the foyer for example), recessed into the wall. Take the chime box cover off and remove the chime mechanism from the wall where it could be hiding.

Installing a Doorbell Transformer

The appropriate time for you to install doorbell wiring is when the ceilings and walls are in their preliminary phase of construction or during remodeling. If you are installing a doorbell in your finished house, a wireless doorbell is the best choice for you as you do not need to cut through the walls of your house for the installation of the wiring. Doorbell wiring in new houses is a very easy task.

Wiring for doorbells is of low voltage which uses about 12 volts. The size of the wire is 18-gauge which is called the doorbell wire. With this fact, you can never go wrong in installing the wiring of your doorbell.


In installing the wire of the doorbell, the wire should be run to the back of each buzzer to the so-called doorbell transformer. The wiring of the doorbell requires a doorbell transformer that can be connected to a circuit with 20 volts of power. The doorbell transformer helps in reducing the electric voltage by 12 volts.

Turn Off The Electricity BEFORE You Touch the Transformer!

You have to make sure that the electricity is turned off before wiring your doorbell transformer into the power station. The breaker should also be turned off and tell members of the family about your task. The doorbell transformer has a neutral screw and a hot screw. The one called the hot screw is where the black wire should be connected and the white wire is connected to the screw for the neutral. Through this wiring, power will be provided to the doorbell transformer. A single neutral wire and hot wire will run from the doorbell transformer into the so-called chime box.


The wiring of the doorbell will utilize hotlines which are usually two in number that will run into the doorbell from the box for the chime. If the buzzer is going to control two areas, then the doorbell will have two chimes different from one another for you to determine the right door to open. The wire will connect to the doorbell transformer containing 2 hot screws dedicated to each doorbell.  It will also connect to every doorbell with the use of the 2 hot cables. When the button of the doorbell is pushed, the current of the electricity will be completed by the circuit so that the buzzer will chime.

See the Doorbell Transformers on 1800doorbell.com


For additional information about our wired doorbell and transformers, please feel free to contact us.