Check inside the breaker box; check for a box behind the chimes; check the basement.

Depending on how much you want to trace the wires, Amazon and others have "Circuit Tracker and Circuit Breaker Finders" that are available in several price ranges. Some have to have the power removed and some don't. I have used several different units and have had pretty good results.

Yeah one time I re-wired a house where the doorbell transformer was located on the hall light box. Previously just laying there. I mounted it to the box properly and it created a slight hum into the walls from the attachment vibration. The lady made me move it, for free ):

I would think yours in the basement or panel by the way you have already traced it. Is the basement finished? Many un-permitted basement finishes from d-i-y's or careless handymen will have the transformer buried up in the ceiling with no way to get to it.

Many un-permitted basement finishes from d-i-y's or careless handymen will have the transformer buried up in the ceiling with no way to get to it.

Yup, true. That was exactly the case with one of my houses. When the previous owner sheetrocked the "rec room" in the basement, he covered up the door bell transformer as well as the main water supply shutoff valve.

Here in British Columbia the standard place for the transformer, if not on a spare knockout in the electrical panel is in the furnace/mechanical room, being unfinished walls, you will find it attached to a knockout on the light switch, furnace switch or maybe attached to the mechanical room light jbox.

Look all round for those brown lvt wires, you'll find them.

I still can't find it, not in the panel, traced the wires, don't have a basement, house built on a slab. Time for a wireless bell. I do think it was buried in a previous remodel by a previous owner.

Same here Slab on grade home. Doorbell transformer is right
next to the Furnace.

HTH
Chris

The area around the furnace was the first place I looked, the bell wires do not go into the area.

lol you could be right about it being buried....is there a problem with the current one? Like I said the other thing to look for is whether it's attached to any exposed lighting "octagonal" box, which is common too (I install alarm systems and we use transformers similar to bell ones, and often place them on the same box (usually adding an extender) the bell transformer's on.

If the basement was finished later, it might be attached to a light or outlet that was there.

If it's faulty you might be able to abandon the wires to the original transformer (but if it's faulty it could become a hazard, and should be dealt with) - I think code here in BC says the transformer must be visible and accessible, but if it got built into a wall it might be possible to replace if you can remove the junction box and replace it with a 'remodel' box, you could attach a new transformer to it - again you might be breaking the rules. If it's attached to an outlet that's drywalled over, by removing the outlet covers and using a good flashlight, you may be able to spot the wires and connecting ring for the transformer that way.

The rules might permit you to put a transformer in a suitable box at a suitable height in the attic, (not sure about this) and connect it to an existing lighting circuit.

I know you've looked but I have to say it's bizarre that it's not located in the furnace/mechanical room or hanging off the breaker box, if it's not in those two areas or perhaps a cupboard under the stairs, I wonder if it was wired or remodelled to code at all.

Cut as many circuits as you can off and walk around the area where you think the transformer is with an AM radio and listen for the buzzing to change tones. The transformer has to be powered up though.

If there is a problem with the present one just install a new one and run some new wires as needed.

It would be better to find it and remove power but that may require opening every outlet to look for the 120 V feed.

I would like to install another transformer, not sure how to hook it to the button. Do I run a new wire and splice into where the present wire goes down into the wall where the front door button is? Do I then go from the button to the transformer then to the chimes? Should I go to one chime, then from that chime to the other? If the transformer I can't find is left in place is that a fire hazard?

Sometimes the trans is in/behind the bell itself.

Went to install the wireless chime and guess what the transformer was in a box behind the downstairs chime.

I am having trouble finding the transformer for the doorbell. My house has a crawl space & no attic. I am trying to get an alarm set up but need this info for the alarm doorbell. No such luck in finding it. Idk what I am going to do. An Electrician was here and couldn't fInd it either. I might not be able to have the system installed after all. Why do they hide these things? 3 of us were looking & no such luck.

The door bell transformer often also supplies the furnace thermostat. Trace the wires from the room thermostat or the low voltage control wires from the furnace. If you have a basement, the usual place is on a joist or sitting on a main support beam for the house.

Thank you pjb999 found transformer in furnace room "attached to a knockout on the light switch"

I have a transformer on the side of my furnace it has a switch & fuse going to it. Then it goes thru a humility control for the furnace. It is a Clare furnace, made in Canada & out business now. The fuse is a 10 amp.

Is this my door bell transformer? The description is similar to that jemdandy.

Because of its location, my first guess is that it is for the thermostat, but easy to confirm: disconnect one of the wires shown in your photo and still if your bell still works!

Or, (second thought), it could be used for both!