Not strictly EE related: ~1940's electromechanical door chime. - Page 1
Forum section: electronics / general

author: poodyp
author_rank: Regular Contributor
timestamp: December 13, 2012, 09:38:40 am
content: So I'm trying to fix or 'upgrade' my grandparents' old door chime and thought people might be interested in it. It hasn't been used in years, and the wiring in the basement has been trashed. I think the bells started to not strike reliably so my grandfather replaced it with a horrible wireless fake sounding chime.As you can see it's a three bell door chime.A closeup of the label.And here's the guts. The arm is connected to ~24VAC, the big ring is connected to the motor, a nice little shaded pole motor, and the points are to each solenoid. Pressing the front doorbell temporarily energizes the motor, then the arm keeps it energized until it's finished. Pressing the back door just energizes the first bell.Here's a short video of it running.As you can see, the solenoids don't move with the greatest of ease. I think I need some kind of grease or lubricant. I'm not exactly sure what's appropriate in this situation.I'm probably going to replace the motor with a micro so I can customize the chime pattern.

author: saturation
author_rank: Super Contributor
timestamp: December 13, 2012, 12:09:42 pm
content: That's very nice. I would try to repair all the original parts, it seems to be working. If you can disassemble the solenoids, it appears they only need a good cleaning. The charm of such a device is the fact most of its parts are old, intact, and the sounds it makes tends to be unique because of resonance with the old parts [ the slow response of the solenoids, and clicking the motor makes etc.,].

author: SeanB
author_rank: Super Contributor
timestamp: December 13, 2012, 06:07:20 pm
content: Clean the solenoids, and replace the rotten rubber pieces ( neoprene seals and neoprene grommets work well) and then reassemble. The motor gearbox will need a refill of oil or very light grease, and a drop of oil on the oilite bushes of the motor and rotor will make it run easier. Wipe the contacts with a cloth dampened with oil and it will run nicely again.There is a Yahoo group on these chimes I saw recently. You should be able to find it easily.

author: nukie
author_rank: Frequent Contributor
timestamp: December 14, 2012, 01:27:49 am
content: Many thumbs up for trying to repair it, I hope you restore it to its glorious beauty. It's a very nice doorbell whereas nowadays its all the silly tiny speakers. Make a video of it in action when you are done.

author: poodyp
author_rank: Regular Contributor
timestamp: December 14, 2012, 02:27:04 am
content: Unfortunately restoring it to full working order would take more work than I think is safe these days. Some time between now and when my grandfather disconnected the chime itself I think an overzealous electrician essentially destroyed the wiring in the basement. The AC line to the transformer is gone and the wiring to the chime is cut beyond too short.what'sdownstairs. As you can see, wires are gone. I can't get that transformer out as I don't have a screwdriver long enough. I'm not sure where there are two transformers. Both of them are scrap as the wires have been cut.Quote from: SeanB on December 13, 2012, 06:07:20 pmThe solenoids are spotless and they're incredibly simple. Nothing more than a bronze bushing and a coil, I think maybe an iron core on the end.I took some more close up pictures of everything.I'm trying to figure out some safe way to run it while the bells are on it but I don't want to jerry build some unsafe solution.

author: PetrosA
author_rank: Frequent Contributor
timestamp: December 14, 2012, 05:16:32 am
content: Quote from: poodyp on December 14, 2012, 02:27:04 amThis is all 24V, or is there a 24V transformer for the motor and a 16V transformer for the pushbuttons? Basically, these are all safe operating voltages at the output those transformers are capable of. You can splice new leads onto the old doorbell wires if you have to. The splices don't have to be in a box.If it's all 24V, you only need one transformer, but you'll need two wires from that to the motor circuit in addition to the pushbuttons circuit. If it were wired for front and rear doors, you should have one pair from the transformer for the motor plus a three wire or two pairs from the pushbuttons coming out of the wall, and between one to three pairs at the transformer depending on whether they spliced the pushbuttons to the power in the chime or somewhere else. If you'd like to get the system working again, I can help with wiring diagrams if you let me know what's accessible.