Western Electric ringer as doorbell

[5415551212]

Hello all,

I'm trying to convert the ringer of a Western Electric ca 1970 to a door chime. I'm an experienced electrician but phone systems are an outlier of my knowledge.

In short, I'm simply looking to trigger the bells as simply as possible using existing house doorbell wiring. I understand the signal should be roughly 90VAC, 20Hz. I've tried briefly applying straight 120V and 24V (both utility 60Hz) directly to the ringer coils and through the phone's network capacitor. I get no mechanical response at all. I would expect at least some movement of the clapper.

The ringer coils ohms seem okay at 1k black-slate, 2.6 red-red/slate. The A-K cap reads out of spec at about 1.2uF.

I don't care about voice signal or even a "ring-ring" pattern--simply that the bells ring while the door button is depressed. I'm just looking to repurpose this piece of my history.
Thanks in advance for any help

Thats a cool project are you keeping the ringer in the phone and the phone is a display piece that rings?
If you want to be undisturbed you'd just leave the phone off hook I love it.
If you like most have unused phone wiring in your house, you could wire up your ring generator / relay wiring so that it hits all the old phone jacks in your house, just run the doorbell wire out to your garage or wherever the old network interface device (NID) was, put your relay there, unhook the tel co line and wire in your relay controlled ring generator.
Then you could simply add other phones if you needed more door bells. Or move the phone to another room and plug it in to a phone jack in that room etc.

[5415551212]

Out of further curiosity: Is there a way to get different ring patterns, say for what would be L1 and L2 (now front door and back door)?

I think PowerDsine are labeled as having 17/20/25 Hz outputs,
at least the older units were.

There would be pins or headers inside, labled F0 and F1 or Freq
These pins are used to control the frequency, they're CMOS 5V input buffers,
So if you did some soldering you could extend them ( and +5v ) out of the unit to a relay contact on a ice-cube relay, like a 4 pole with NC/NO contacts.
the ice cube relay would be activated by the back door button, use 2 poles for the 12V and 2 poles to set the ring frequency.
When the back door button is pressed it takes the 5V input butter and either shorts it or opens it as you configure.

Where  0v = '0' and 5V = '1'
the truth table is something like
0,0 = 50Hz
0,1 = 16.7Hz
1,0 = 25Hz
1,1 = 20Hz

So you could have different doors have a different frequency, like 16.7Hz for back door, 25Hz front door.

[TelePlay]

I think PowerDsine are labeled as having 17/20/25 Hz outputs,
at least the older units were.

Yes, some are. I did some research. Seems there are 4 different DSine generators out there.

There are 3 board mounted types

12VDCin 50VACout at 17/20/25 Hz
24VDCin 50VACout at 17/20/25 Hz
12VDCin 70VACout at 20Hz

There is one pigtail wired type

12VDCin 70VACout at 20Hz

There may be others, this is what I found quickly today.

[rotaryclub]

Knowing that results are rarer than questions on this forum [and in life], I'd like to share my success with the phone ringer to door chime project.
I chose my battles--taking the easy path with a DSine ring module from thEbay and a 12VDC wallwart but spicing it up with different ring times for front and back doors.

Thanks to all who helped.

[5415551212]

Knowing that results are rarer than questions on this forum [and in life], I'd like to share my success with the phone ringer to door chime project.
I chose my battles--taking the easy path with a DSine ring module from thEbay and a 12VDC wallwart but spicing it up with different ring times for front and back doors.

Thanks to all who helped.

Glad to see it worked, if you want to clean up that cord we recently had a thread with neat trick for cleaning them:
https://www.classicrotaryphones.com/forum/index.php?topic=28929.0
been meaning to do it myself.

[rotaryclub]

BTW--one more slap in the face...

I'm still not sure if I prefer hanging it with the cover off. I mounted it through pre-existing holes in the bottom plate. Then I remembered that the cover screws in through the bottom. 
I didn't have a great solution for keeping the handset on vertically anyway and ended-up going back to bridged wiring so the ringer was active off-hook.

[Dave F]

BTW--one more slap in the face...

I'm still not sure if I prefer hanging it with the cover off. I mounted it through pre-existing holes in the bottom plate. Then I remembered that the cover screws in through the bottom. 
I didn't have a great solution for keeping the handset on vertically anyway and ended-up going back to bridged wiring so the ringer was active off-hook.

Not to be a meddler but ... 

This problem would be avoided if you used a 554 (wall phone) instead of a 500 set!

DF

[5415551212]

Yeah looks like you mounted it where the door chime was, If you don't have any landline service and you have old abandoned landline wiring, I would just patch the ring generator into the house phone wiring, then you could put that 500 set on a desk like a regular phone. You could probably ring up to 3 phones off that ring generator.

[rotaryclub]

Gheez, I get ribbed on an electrical forum for not using a rectifier and filter cap and jibed on this one for not having a wall-mount model! 

I like the idea, @5415551212, of setting it up like a regular desk phone. Having thought about it, though, the places in the house with an old block or RJ11 jack aren't great locations for a doorbell. I like to have plausible deniability of being at home!

[5415551212]

Gheez, I get ribbed on an electrical forum for not using a rectifier and filter cap...

Were they suggesting using a the existing 16 VACbell transformer?
 LOL
That would be a creating a DIY linear supply, the reason why not a rectifier and filter off the existing bell transformer is the same reason we don't use the classic "linear" supply for hardly anything anymore.
Old linear supplies do run at 50/60 Hz off a transformer like a door bell transformer, and thats lots of iron and copper to avoid saturation and heating.
Linear regulation wastes (Vin - Vout) * Iout as heat.
Using 16 VAC to make a regulated 12 V DC with a linear regulator is inherently lossy because the rectified DC is around 20-21 V, the linear supply would be about 58.8% efficient.
A classic "linear" supply is basically:

• Transformer (mains 60 Hz) steps voltage down
• Bridge rectifier makes DC
• Big electrolytic caps smooth it
• Linear regulator (or just series pass element) holds the output steady by burning off extra voltage as heat

A switch mode power supply (SMPS) AKA light weight 12V wall wart, which you likely used, does regulation by first converting to DC then rapidly switching energy into an inductor/transformer and then averaging/filtering it. So efficiency is probably above 90%

Switching regulation wastes little energy because the "pass device" is either fully ON or fully OFF.
A transistor used as a switch has:

very low voltage drop when ON (so low conduction loss)

near zero current when OFF (so low off-state loss)
SMPS supplies have some switching losses during transitions, but modern MOSFETs keep those small.

SMPS then can use a much higher frequency transformer (no huge 60hz bell xfromer to saturate).
In an SMPS, the mains is rectified first, then switched at tens to hundreds of kHz (or higher), so the transformer/inductors can be much smaller and often have lower loss for a given output power (and you can design them for the exact operating point).

Also your overload and short circuit protection are probably built into a North American "Class 2" power supply, with a linear you'd need a 1A fuse.

In the -48V telcom world we have been upgrading to SMPS where we can for decades.
Cheers
Stephen

[rotaryclub]

The electrical forum is great. About half suggested off-the-shelf kinds of solutions and half theorized iron and copper paths. Part of me did want to stay old-school, but I ultimately wanted the project "done"...with future modifications possible!
I'm well familiar with SMPS, but mostly in the realm of 480V motor drives and starters. This has been a good foray into this system.

In the -48V telcom world

I often forget, until I occasionally deal with it the field, that + can be grounded too!