You Rang?

We all need a way to ensure callers can gain the attention of the butler prior to admittance (naturally tradespeople use the rear entrance...

We all need a way to ensure callers can gain the attention of the butler prior to admittance (naturally tradespeople use the rear entrance). Typically this need is addressed with the addition of a plastic doorbell push on the outside coupled to either a simple battery powered bell or in those really posh houses a digital chime station with all your favorite olde tyme tunes.

Clearly such simplicity has no place in this project and thus we find ourselves with the challenge of meeting this requirement but in an interesting way.

Firstly to that doorbell push thing - it’s normally a rectangular plastic box, probably black with a white button. Some people opt for B&Q special “antique” brass. It’s also the first tactile point of contact with your house - doesn’t it deserve a little more thought?

An interesting item cropped up in our Favourite Sellers feed on eBay leading to inspiration and the hatching of a cunning plan. The item in question was an emergency stop switch from an old machine. Featuring a cast iron casing and a great big button made of brass and embossed with a big E it was the obvious choice.

Fortunately the button had both push to make and push to break contacts (you need push to make for a doorbell push, push to break would lead to a headache and permanently ringing ears). The downside was that it was big, in all dimensions - this was not something we’d be throwing at the door frame with a bit of sticky tape - this was going to need some workshop time to machine a mounting bracket.

Fix > Connect > Use

The bracket provides a mechanically secure mounting and also allows the push to sit at 45 degrees across the right angle formed between door and wall. With the bell push installed the next search was for an appropriate bell…

Is there such a thing as a “feature” door bell ? It turns out there is; in this case it’s 10kg of explosion proof cast iron, 240v powered factory bell. This is a big proposition BUT had all the correct attributes; unusual, retro/industrial aesthetic and pretty much a guarantee the bloke down the road does not have one.

Mounting the bell required some thinking and in a very similar way to the concerns expressed in the post about the light switch you can go very wrong with what seems like a simple part of the overall project. The issue here is the temptation to simply screw the thing to the wall with whatever is lurking in the SortTainer (other storage solutions with less white and green are available) and walk away. There’s nothing mechanically wrong with this approach, there are four mounting holes and even a puny screw is not going to be challenged holding 10kg mainly in shear… the problem here is one of aesthetics.

Shoulder bolts and washers

This bell would have been bolted or possibly coach screwed to the wall, the visual weight of the bell demanded similarly weighty mountings and this required another visit to the workshop to machine some special shoulder bolts from hex brass stock. These special bolts work in combination with 6mm stainless steel studs in hollow wall fixing (the mounting surface is the American Barn Siding cladding and is 20mm thick with a 20 > 30mm void behind). The finished result makes it appear that the bell is bolted to the wall with large brass bolts.

The other challenge with this project was around safety - unlike most doorbells this one needs a full-fat 240v power supply which introduced the not altogether welcome prospect of sending that in and back out of the wall to the doorbell push. Whilst doing this is not an issue we’d much rather not do it and more to the point we’d prefer not to present 240v in the push just in case.

We looked at two solutions (after discounting just living with 240v to the push); rewind the bell coil(s) to drop the voltage down to that achievable with, for example, two D sized batteries or use some kind of relay to switch the bell. We opted for the latter approach because it allowed us to avoid the need to significantly modify the bell and with solid state relays being very cheap and tolerant of a wide range of switching voltages they seemed the logical approach.

You can see the wiring used (it’s in the prototype stage in the image below) - what this basically allows is the use of the PP3 9-volt battery to switch the 240v live feed to the bell. This means only 9 volts is traveling to the bell push eliminating the concern of presenting 240v to the external push. The observant amongst you may notice that the images of the bell push show earth wiring - this is there for a) just in case scenarios where someone else re-purposes it and b) because it looks better to populate the earth tag.

Prototype, honest

This was a very interesting portfolio project combining all the things we like to do; sourcing of the unusual and unique, re-purposing, machining bespoke components and integrating this into a modern home.