Making a telephone ringer

[The Spy Husband]

Apologies if this is has already been asked. I had a search but couldn't find anything.

 

I hate using phone fx and would much rather have a practical ringing phone on stage - ie, press a button offstage to make it ring and it automatically cuts off when the handset is picked up. Our club used to have such a device but it has since gone walkies and no-one seems to know its whereabouts.

 

Anyone have a DIY instruction manual?

[Ynot]

There have indeed been several topics on this...

Try putting 'telephone ringer' into the BR search tool!

[The Spy Husband]

There have indeed been several topics on this...

Try putting 'telephone ringer' into the BR search tool!

 

I did... but nothing!

 

A concurrent post has been automatically merged from this point on.

 

Ah, used the Google one at the top this time. Success!

[tolley1466]

Could you not connect a phone to the theaters network?

I've seen a few theaters with phone sockets near the stage....

[Ynot]

Could you not connect a phone to the theaters network?

I've seen a few theaters with phone sockets near the stage....

 

<sighs>

 

1. Theatre phone network may not have the correct ringing cadence.

2. Can you guarantee that no-one will ring the extension being used when the phone is NOT supposed to be ringing?

3. Can you also guarantee that the person dialling always dials the correct extension number...?

 

That's just off the top of my head!

[TomHoward]

I have not researched the other options suggested but every theatre tech and his dog round this way (as we are based near the BT Labs at Martlesham) seems to have one of those Line Testers from BT which run off a PP3 battery, and they do exactly as you describe - you plug a phone into a socket on the box, press a button and it rings until you cancel it or they pick up.

[Andrew C]

one of those Line Testers from BT which run off a PP3 battery,

That's easy for modern phones, but I doubt that it will drive old bell phones. They need a fair bit of power for the bells.

 

Do they ring in the correct cadence?

[themadhippy]

A quick google finds several options including This.Also in the dim an distant passed maplins did a phone ringer kit,it had a few quirks,like still ringing the phone when lifted,but alowed you to set up whatever ring pattern you required,might be worth given them a call see if they've still got a copy of the circuit diagram.On the subject of using an internal phone network,yep been there done that,however often the ring tone will be different for an internal call,so make sure the phone can receive external calls.If you keep it unplugged up until needed you'll cut back the risk of it being rung by some random miss dial.The "advantage" of using the internal network is you can have a nice little chat with the cast,not that I would ever do that of course.

[TomHoward]

That's easy for modern phones, but I doubt that it will drive old bell phones. They need a fair bit of power for the bells.

 

Do they ring in the correct cadence?

They have step-up transformers in them and basically drink batteries, I've not tried them on anything pre-70s but they do seem to drive a later bell phone okay. They do seem to ring in the correct cadence (if that's what you're referring to).

[boatman]

IIRC, the old standard BT ring tone was 75VAC @ 20Hz with a cadence of 400mSec On, 200mSec Off, 400mSec on & 2Sec off. It shouldn't be too difficult to make a circuit which does that with a couple of 556 timers. Feed the output to a power transistor which in turn drives a step-up transformer and you have your ring tone. I'm sure that Ynot will keep me right.

[Wrighty]

I designed a unit, loosely based on the drive circuitry from the Maplin design (albeit beefed up even more so it'll drive pretty much any phone) but with a PIC microcontroller instead of logic gates and timers to drive it. I've built a couple for people I know who are in the theatre business and I've got one myself which I lend out now and again. It's all properly built on a PCB in a nice ali case and has selectable US/UK ring, with possiblity for others, with firmware changes. It's got a BT socket and an XLR on the back, allowing you use standard BT extensions or mic leads (with appropriate adaptor at the far end) for wiring. Selling price was about £85 from what I remember.

 

If there's a market for these things, I might seriously look at making a batch and getting some panels properly printed.

[The Spy Husband]

If there's a market for these things, I might seriously look at making a batch and getting some panels properly printed.

 

 

That might be an idea. See if I can get the club to cough up some cash for one!

[Malcolm Gordon]

maplins did a phone ringer kit,it had a few quirks,like still ringing the phone when lifted,but alowed you to set up whatever ring pattern you required

I built one of these in 1996 and in my experience the phone stops when off hook if correctly wired with a BT connector. It can be calibrated to give the correct cadence (400ms on, 200ms off, 400ms on, 2 sec off), although the UK/US switch just cuts out the middle 200ms off, rather fast for the US, which is usually 2 sec on, 4 sec off, unless it varies between phone companies. The timing can be recalibrated, however.

 

This page may be of interest for those making their own ringers.

 

The ringer is still very useful when the play calls for a modern phone, but we also have a number of older bell phones, which the Maplin won't drive (as already noted), and the ringer we use (which utilises a BT bell transformer) has to be manually operated in sequence, quite feasible but requires more concentration than "switch on and leave it" (as long as you remember to clear it before the phone is put back on the hook).

 

I would rather not rebuild my unit, but wonder if someone could devise a simple external add-on relay unit, BT plug to BT socket, that would up the current when required to drive an old phone. My electronics design skills aren't up to it, I'm afraid, although I could build someone else's design.

[d_korman]

All you need is a 50V 50W transformer and a push button and ideally a 1A fuse. Connect to the Ring and B lines on the phone - terminals 3 & 5 on modern phones. Nearly all modern phone will ring OK with this drive. Older bell phones will need the gongs adjusting to work at 50Hz - just ring the phone and rotate the gongs to get the best sound. The sound is not quite the same as when using a 20Hz ring signal but in 30 years no one has ever complained.

 

You DON'T want the phone to stop ringing when the handset is lifted, since if the talent does not replace the handset correctly afterwards and the phone has to ring again you are in trouble. It's happened to me more than once. You generate the ring pattern manually and just watch for the handset to be lifted.

[David Duffy]

The ringers I used to make used a PIC chip and had selectable US / AUS (same as UK?) cadence. It had start and stop buttons. When the phone wet off-hook, the ringing was cancelled so was fairly fool proof.

 

I have started an updated board design, but I'm in Australia so that doesn't help the OP I suspect.