Ringing the bells

[royalbox]

Hello,
I read some information at britishtelephones.com about how the bell ringer works (I'm sure you already know!) which states: "Most of the world uses frequencies between 20 and 40 Hz" and "The voltage at the subscribers end ... could be between 40 and 150 Volts".

On a micro controller it's quite easy to produce a sine wave of, say, 30Hz oscillating between 0 and somewhere below 5V. I'm wondering if it would be relatively simple to convert that to the higher voltage required to make a bell set ring. I assume it would be between a negative and positive voltage (-50V to +50V perhaps?). Or perhaps it would be simpler to just have the micro controller output +5V for on and 0V for off but I suspect that the circuit would become more complex.

I know you can get those little ringer devices, someone is selling them on UK ebay for about £20 each.

If it could be done with just a few readily available and relatively cheap parts I'd like have a go, though I'm an electronics novice. Any electronics person here have any ideas if this is doable?

Thanks for any help.

[Owain]

It's basically just a 100 volt line audio amplifier running into a 4k - 1k load (albeit rather inductive).

[TelePlay]

     Regular Member Post

I read some information at britishtelephones.com about how the bell ringer works (I'm sure you already know!) which states: "Most of the world uses frequencies between 20 and 40 Hz" and "The voltage at the subscribers end ... could be between 40 and 150 Volts".

I know you can get those little ringer devices, someone is selling them on UK ebay for about £20 each.

I and others have used these DSine ring generators which work well using one, or two in parralles 23A type 12 VDC batteries.

     https://www.ebay.com/itm/New-2PCS-RINGING-GENERATOR-PCR-SIN03V12F20-C-Power-Dsine-3W-12VDC-TO-70V-20Hz/252566429110

They ship out of Israel to world wide locations and sell in quantity of 2 to keep the cost per each after shipping down. The prices of these has increased over the past 5 years but they are worth it if you want to ring a phone off of a very small battery. Batteries last a long time and are quite inexpensive. Using one of these vs the time, effort and cost of designing a building an equivalent ring generator to me makes a lot more sense, unless creativity is the motivation.

The batteries are same size as a AA battery except only about 2/3rds the length.

     https://www.ebay.com/itm/5-Pcs-23A-A23-E23A-GP23A-MN21-12V-Alkaline-Battery-FRESH/192670858169

23A battery holders are readily available and inexpensive

     https://www.ebay.com/itm/5Pcs-23A-A23-Battery-12V-Clip-Holder-Box-Case-Black/253940131100

And a lot cheaper of you order them from China, with a 2-3 week delivery time.

Using one of these versus the time, effort and cost of designing a building an equivalent ring generator to me makes a lot more sense to me unless, of course, it's being done with creativity is the motivation.

The one I made is documented in detail including images of the battery showing their size relative to a phone and the generators is at this link:

     http://www.classicrotaryphones.com/forum/index.php?topic=13838.msg144697#msg144697





I've gotten to the point in my life where I take the best/easiest/fastest way to do something rather than reinvent the wheel and these DSine ring generators are one of the best telephone "tools" I every purchased for testing ringers and making phones ring on stage during theatrical plays. Much smaller to haul around than a Panasonic 616.

[Jim Stettler]

The black magic ring generator is similar. They will make them for frequency ringers as well.
I thought about using  a ring relay to trigger a black magic freq. generator. to ring frequency ringers.
Sandman sells a modular ring relay

http://www.sandman.com/wizard.html#CID2L

http://www.camblab.com/datashts/lr12.pdf

camblab is a member but they haven't posted since August 2017

[royalbox]

Thanks chaps. I mentioned in my post about those ringer generators. We spoke about them before Teleplay in another thread where I was talking about using a phone as a countdown timer. I've been working on this (just for my own interest) and got to a stage where I just need to make the phone ring for it to work.

The fact is, I'm in the UK and those ringers are sold on ebay here singly for £23 delivered (nearly $30). Too much as soon as you start to want 2 or 3. There can't be much in them at that size but they've been 'potted' so you can't see!

I was just asking on the off chance that someone had already posted a circuit for doing this somewhere. My electronics knowledge is not great.

It's basically just a 100 volt line audio amplifier running into a 4k - 1k load (albeit rather inductive).

Too vague for my knowledge, sorry. Not sure if you're referring to what's in those little ringers or not.

Thanks again all.

[Owain]

There are some ring generator / oscilllator circuits discussed at
http://www.classicrotaryphones.com/forum/index.php?topic=6141.0

[royalbox]

There are some ring generator / oscilllator circuits discussed at
http://www.classicrotaryphones.com/forum/index.php?topic=6141.0

That's great thanks, I'll go and have a read.

[royalbox]

I've just noticed that you can get the ringers directly from Israel for about £30 for 2, so you are right Teleplay. I was only looking at UK listings before. Not sure whether I'd be clobbered for import duties and VAT though.

[andre_janew]

Would the magneto from and old magneto telephone ring the bells on a more modern telephone?  I'm just wondering if it would work.

[Owain]

Would the magneto from and old magneto telephone ring the bells on a more modern telephone?

Certainly will :-)

[royalbox]

Currently on ebay there are new old stock PCR-SIN01-V12F00A ringer generators being sold in lots of 2 or 10. I bought 2 for $14.65 shipped (£11.63). Don't know if these are any good but I though it worth taking a chance at the price. The lots of 10 are currently $72.14 (without shipping). Thought I'd pass it on.

=============================

EDIT: Link and images added for convenience

     https://www.ebay.com/itm/2x-POWERDSINE-PCR-SIN01-V12F00A-TELEPHONE-RINGER-DMA10-12V-IN-Vout-50Vrms/183044581766

[TelePlay]

     Regular Member Post

Yes, they have and I've never talked about them because they are PC board mounted. They do offer 3 ring frequencies but only 50 VAC out using the same 12 VDC power source.

I've found the more expensive DSine ringers with wire leads a lot easier to use, to attach the wires, than to cut a piece of perf board, mount the chip, wire the circuit and then mount the board (a bit of hot glue on the wired chip works just fine).

Then, of course, I'm not that into electronics so building the board to me would take time and I would never need the two other frequencies offered. I found it very easy to use a few clip leads to make the wired one work (below image).

I think they are lower in price because they don't sell like the wired version. These would work but would take a bit more effort to build into a ring generator device, including switches to select the ring frequency. Would have been nice if the seller would have included an image of the circuit inside the chip, defined the pin out markings.

[royalbox]

I'm okay with soldering so thought it worth given them a try for the price.
I can't find any wiring info online though. I expect that INH is inhibit but not sure whether you connect it high or low. F0 and F1 I suspect control the frequency by connecting them high or low in different combinations. I don't expect them to come with any wiring instructions as they are selling them as old "out of date" stock. It says on it "Date: 0145" which I think means week 45 of 2001 but I might be wrong.

[TelePlay]

     Regular Member Post

I'm okay with soldering so thought it worth given them a try for the price.
I can't find any wiring info online though. I expect that INH is inhibit but not sure whether you connect it high or low. F0 and F1 I suspect control the frequency by connecting them high or low in different combinations. I don't expect them to come with any wiring instructions as they are selling them as old "out of date" stock. It says on it "Date: 0145" which I think means week 45 of 2001 but I might be wrong.

I sent the seller a message asking if he could add the circuit and/or pin out definitions to the listings for send it to me in a message reply. If he posts or sends one, I will attach it to this reply.

The eBay listing says "new, old date code" which is confusing. If the date code is correct and the item is new, then it is NOS. I doubt age makes a difference with these. The fuzzy, off center eBay picture doesn't help either.

If  you don't mind the extra work of building a perf board, then these would be a good deal and selecting the 20 or 25 Hz by hard wire (eliminating a switch) would make it easy to build.

[TelePlay]

     Regular Member Post

The black magic ring generator is similar. They will make them for frequency ringers as well.
I thought about using  a ring relay to trigger a black magic freq. generator. to ring frequency ringers.

camblab is a member but they haven't posted since August 2017

I just found this topic where Camlab posted everything about their Black Magic generator in 2013, at this link:

     http://www.classicrotaryphones.com/forum/index.php?topic=4748.msg96003#msg96003