We have a number of telephones in our props. My old group had a (I think it was a) transformer (or at least a gadget) which plugged into a mains socket and made all our phones ring when a button was pushed. The advantage of this was that when the receiver was lifted the phone stopped ringing. Does anyone know where I can get one of these transformer from? Or a kit to build one without having to take out a mortgage. I am told Mappin Electronics used to supply a kit but I spoke to them yesterday and they didn't know what I was talking about. I have moved and my old group is too far away to go back and borrow. Help, please.
Steve

I seem to remember that the voltage for classic telephone ringers is 50V, but can't remember if this is AC or DC. Or indeed I could be wrong!

Hang on a minute.

From: http://faqs.org/faqs/theatre/stagecraft/faq/

In the UK, phones are rung with 50V A.C., at 25Hz. If want to ring a
phone where the clapper oscillates between 2 bells, remove one of the
bells, and run it from a transformer giving 50VAC, 50Hz. If you want to
ring a more modern phone, a lot generate the ring frequency themselves,
which makes it easier. Get hold of a master socket (the type with the
surge arrestor, out of service resistor and a capacitor inside), and
apply 50VAC 50Hz to the terminals A and B, and the phone will sort out
the frequencies itself.

There was a long discussion on the board about this some time ago.
a search may give some results.

I think BT's network used to use 70v at 25Hz for the old bell type,

I use a converter ringer from an old BT manual switchboard, which is basically
a transformer. A Conn Ringer 7a if memory serves me. This gives a 50v output.
I fixed a bell push and a master socket to the case. A telephone extension lead plugs
into the socket an gores the thr phone. I have found that this works well enough for
both bell type and tone ringering telephone. You just have to simulate the ringing
cadence on the bell push.

I think you will find that BT uses 17c/s ringing.

When I worked for the Beeb, my TV studio had a 17C/s generator in a bay to ring the bells in the phones in the studio area. The reason for this wierd arrangement was that in rehearsal and transmission conditions the bells were disconnected and only flashing lights were available for indicating that a call was coming in.

As to voltage, some years ago I installed a couple of ring detectors for a hospital radio service. One detector worked OK while the other refused to detect the ringing voltage. When a meter was put across the line during ringing, one line had about 45vAC while the other was around 30v AC. In other words, ring voltages can vary! However, 50v AC is a good bet.

My last amdram club had a custom built ringer which seemed to produce 25c/s at about 50v, but the actual ring speed (ring - pause - ring) was too slow, so I always ended up doing it manually.

As already pointed out, modern phones produce their own rings by detecting the incoming ringing - it's getting a good ring on a 'true' bell phone that's the problem.

From what I have read on this thread, Uncle Harvey seems to have solved the problem!

Dave from Dumfries.

Ok

I think i was the one that asked about this last time.

Basically in the end we didnt have the electronic skills to do this so we used

http://www.precisiovision.freeuk.com/

and yes I realise its expensive for the average group but we thought it worth it as nearly all our plays use phones and it has paid for itself.

It rings everything from old style bell telephones right upto modern cordless and it stops when you pick it up etc.. anything witha standard BT plug on the end basically

It can produce a Uk style ring or a long US style ring or a short US style ring.

You press the start button once and it rings until it is either picked up or you manually press the stop button (if it is meant to stop ringing before anyone picks up)

No fuss no muss and the service from the guy is superb... answer emails super fast if you have any questions of issues.

But it costs a bit


EDIT - one style of phone we have never tried is an old candlestick one but I dont think they come with bt plugs ... we did use a candlestick phone but we got a repro when we needed it.. still made the bell sound.

Hi,

I have recently built a unit for my drama group. it works with all phones I tried it on, new and old.

Essentialy it consists of a 240v to 2x24v transformer, so it generates 48V AC this is enough to make any uk specified phone ring. I then also rectified (to convert it DC) 1 of the 24v taps and fed it through a long cable (10m) to a switch, so that it switches a 24V automotive relay. this allows it to remotely controlled from the lighting box! it is a bit crude, but does the job. the operater just has to be consistant when pressing the button. It was used in my groups last production just last week, and we used it to sound like a french phone ringing. each country uses a differnet cadence, for example the uk is 2x0.3 sec then a 2 sec gap, then repeated. A frenech ring signal is 2.5sec then a 3.5sec gap which is repeated.

If you would like some more detail contact me off list.

I could build you one at cost price if you are intrested.

I am not sure where you are loacted in the uk, I would consider lending if you are not to far away from me.

let me know.

Ian
First, very, very sorry for not coming back sooner. Two awful excuses, computer problems and then our show. We managed with a doorbell this time. I am a member of the Bungay Theatre Group. You've probably never heard of Bungay, it's as far north as you can get in Suffolk without being in Norfolk.
Your offer of help is greatly appreciated. I think I understand what you are saying but I have a couple of questions and things to check with you. Can we continue this off board?
My email is steve-gwen.doyle@tiscali.co.uk
thanks again Steve