Doorbell replacement

I would just buy a battery powered bell. The duty cycle of door bells means that a couple of C size (or better still D size) will last a couple of decades without replacement.

Meanwhile, your doorbell transformer (assuming an old iron core device) is consuming power 24/7.

Tim

I thought about this but the problem is that the transformer would need to be disconnected first if I am to use the existing cabling (and stop it consuming power 24/7) and no-one seems to know where it is - not even the electrician. Rather than replace the cable, I would go wireless but this leaves the problem of the redundant transformer.

They’re usually (but not always) situated near your main consumer unit.

Tim

With a bridge rectifier and a capacitor you would get near 6V DC from your 4.5V AC. Is there a 6V DC bell available? Incidentally, many old doorbells were 4.5V DC powered by a type 126 'bell battery' which was three 1.5V cells packaged in a cardboard box with two screw terminals on top.

This is where both electricians looked and there is no sign of it there. After switching off the circuits one by one, I now know it is connected to the downstairs lighting circuit. My concern is whether a transformer that is out of use can responsibly be left in place. Is it likely to be connected via a junction box or could it be connected to a ceiling rose?

That seems to be a different problem from the one you started with. You have a transformer of some age buried somewhere in your ceiling (probably). That seems like a fire risk?

I think it's a continuation of the same problem. I have a broken bell connected to a working power supply. I was going to fit a new bell but this seems so be impossible (as 4.5 V AC bells are not available). I share your concern that leaving a mystery transformer somewhere in the ceiling is a bad idea. Finding it would seem to be the challenge.

I have only encountered one door bell transformer fire.

The transformer was in the loft and left connected to the mains.

Someone got rid of the doorbell push and left the 8V cables twisted together.

Metal detector? Although, as Adam says, they probably don't burst into flames very often.

I'm not sure that it is a problem. A disconnected transformer does not draw any measurable current (Lenz's Law, back emf and all that).

Ours, fitted before we moved here, is conected to a junction box which also feeds the downstairs lights, and is in an almost straight line from the door to the bell.

Is your house stand-alone or one of many of the same design? If the latter then it might be worth asking neighbours if they've got a mains-operated doorbell and, if so, do they know where the transformer is.

Good idea, but the house was built in the 1930s so a lot of retrofitting has taken place. I suspect most of the neighbours will have wireless doorbells.

short it out and play "hunt the buzzing sound"?

They can be relatively small. This one has a nut on one side, for the mains side mounting scheme. And the nut secures the transformer to a metal surface on a panel. That's so the consumer cannot touch mains potential. In previous generations, the mounting scheme was much nicer for the consumer (easier to repair!).

And yes, it hums a bit, suggesting an impedance-protected transformer.

I can always rely on Hammond, to give just a tiny bit more detail. They choose to call it "energy limiting" (when shorted).

I might be able to get a multimeter, onto the two screws. And then see if the AC volts, is in the ballpark value on the rating plate. Usually transformers are "off" with regard to their spec, so don't be alarmed if it said 16V and it was 14V or 18V. The voltage rating, may be measured while the rated current flows, and the open circuit voltage could be higher. On a bell transformer, there might be an even more significant difference (maybe 20V on a

The bell transformer does not absolutely have to go into an obscure spot. There must be some rules as to what is "reasonable".

Paul

Mine's DIN rail mounted, inside the consumer unit

I find that

Honeywell Home E2640

is listed at a nominal 8 Volts, but the specs say 5-8 Volts AC.

Give it a try, see if it rings? Five to eight pounds...

Thomas Prufer

I have a doorbell transformer. Mine is alongside the consumer unit and there is a switch to interrupt the power input to it. My transformer has output wiring options of 3V, 5V and 8V.

If you have a similar transformer, then you would perhaps be able to change the output wiring to 8V. If it is powered via the lighting circuit and it isn't near the consumer unit, then it's next most logical position is close to the doorbell unit or to the bell push by the front door. Have a look around those locations.

If you want to reuse your existing wiring unchanged, my suggestion is to have a look round jumble sales, collectors fares, car boot sales etc, because older doorbells (with a clapper hitting a bell) were commonly wired to a 4.5V (old style doorbell battery) or 6V (Lantern) battery and would be adaptable to being powered by your transformer instead of using their internal battery. The older style bells would not be bothered by AC or DC power.

If you are prepared to take a gamble, this item

More expensive but less of a gamble are:

Finally although you say the existing one is falling apart, is it possible to refurbish it?

And to lighten the mood, how about this alternative?