Making a phone ring - Community Theatre

[winkydink]

I am involved with my local community theatre.

A stage manager who knows that I dabble in vintage phones asked me a question that I could not answer, so I figured I would try to consult some experts on this forum.

She wanted to know if I could hook up a phone on stage so that the phone would actually ring.  I told her I didn't know how, but I would try to find out if it was feasable.

Is there a way to do this within the limited [i.e. low cost/no cost] budget constraints of a community theatre ?

Thanks in advance

[twocvbloke]

When I was helping out at a small theatre (The Little Theatre, Colne, Lancs, er, UK!!!), they had a box that they used for ringing phones, all it was inside was a mains to lower voltage transformer (never measured what voltage), and the phones (GPO 746) used were wired with only the bell circuit connected, and the bells adjusted so they rang on 50Hz rather than their normal 25Hz...

And the whole lot was controlled with a couple of buttons (2 connection points, for either the phones or for a doorbell), and someone had to push the buttons manually to get the right ring cadence...

Another option would be a linesman phone, with a built-in ring generator, they can be obtained relatively cheaply and work well, and usually put out the right ringer frequency too so standard unmolested phones can be used. If their budget can't stretch to that, maybe offering the use of one from your collection (if you already have one, or can purchase one) may help them, just make sure to slap a sticker on it with "Property of ..., Tel. xxx-xxxx", community theatres like people who donate the use of useful things like that...

[TelePlay]

You can google "telephone ring generator circuit" and pick from many schematics from simple to complex if you want to give that a try. Getting 30HZ and 90 VAC is the trick.

You can also look for a Tellabs unit which puts out a constant 30 HZ at 90 VAC which you can hook to a phone and ring it by manually closing a switch in the line ( http://www.ebay.com/itm/390392030274 ). They vary in price over time on eBay. There is a smaller unit that is used, I think, with 1A2 systems that will also put out 30 HZ at 90 VAC

A WE 118A Frequency Generator will do the same thing, if you can find one
( http://www.classicrotaryphones.com/forum/index.php?topic=7026.msg79650#msg79650 ).

If you want to have two phone be able to call each other, a POTS simulator is needed but I see they are really expensive on eBay right now.

I paid a lot less for both my 3 ( http://www.ebay.com/itm/320776933853 )

and 5 ( http://www.ebay.com/itm/230666377787 ).  These are just two examples. Listings come and go.

A TT3 will only handle 2 phones with two digit fixed numbers at normal cadence (2 second ring at 30 HZ and 4 seconds pause). The TT5 can handle up to 4 phones with standard cadence and the ability to programming lines for other ring styles and phone numbers for each line.

Using straight line power at 60 HZ will make the ringer sound funny or may not work at all. That's why I first suggested looking for a circuit you can build to cut the frequency in half and drop the voltage 25%.

You can also do a search for "ring generator" on this forum and look through the hits to see what others have suggested.

I've had 3 working phones on stage at one time with the master phone in the booth using a TT4. I could call any stage phone or they could call each other. It was so real the audience didn't know what was being used or what I paid to do that. I've done phones on stage so many times, I put in a permanent dedicated Cat5 line from the tech booth to the stage because I got tired of running that line everytime I needed a phone on the stage.

Lot of options, none of them "cheap" and building a circuit is time consuming. Hope this helps.

[Owain]

If the theatre has a pbx then the easiest way may be to run extensions to the stage and the sound desk.

As long as you can trust no-one to call the stage extension in error.

[poplar1]

We had to give a college president a 4-digit intercom number on a Comdial DXP when everyone else had 3-digit, just to make sure no one dialed him by mistake.

[HarrySmith]

I can think of 2 inexpensive ways to do it. One would be to record a ring and place a speaker near the phone that is supposed to ring. The other is to use a magneto ringer box, remove the ringer and mount it near the phone and run wires from the mag to it.

[TelePlay]

Another inexpensive way for a theater, which already has the equipment, is to do what I read somewhere a year or two ago when starting my search for how to ring a phone.

I did not try this but the writer said it would work. The writer recorded an audio file of a 20 HZ full sine wave tone in the cadence sequence wanted, say 2 seconds of tone and 4 seconds of silence. The writer than played the file on a computer and fed the signal into a power amplifier.The writer hooked the speaker outputs up to the phone and cranked up the volume on the amp until the phone rang as the tone played. I would guess the power amp would have to be capable of providing enough power to activate the ringer coils. A transformer to match impedance may be necessary.

The "theory" is that a loud enough AC signal would ring the phone. No cost to a theater to try this, except for the cost of a phone and the wire. If you try this, let me know if it works. If it does work, at least the phone will stop ringing on lifting a handset, something hard to control from a tech booth using a speaker for as you know, actors do funny things like double clutch a pickup or block the sight line.

Here is a link to a discussion about this technique.

http://tinyurl.com/8bcgo28

[poplar1]

Here is a  117A ring generator currently offered on Ebay: Item number: 160856633985.

I provided a 48A hand crank generator and a small 118A ring generator for a local theater group, and they prefer the 118A, particularly in a play like The Man Who Came to Dinner where there are lots of phone calls.

[winkydink]

Funny you should say this, because our Theatre company is doing "The Man Who Came to Dinner"  :-D

[winkydink]

You can google "telephone ring generator circuit" and pick from many schematics from simple to complex if you want to give that a try. Getting 30HZ and 90 VAC is the trick.

You can also look for a Tellabs unit which puts out a constant 30 HZ at 90 VAC which you can hook to a phone and ring it by manually closing a switch in the line ( http://www.ebay.com/itm/390392030274 ). They vary in price over time on eBay. There is a smaller unit that is used, I think, with 1A2 systems that will also put out 30 HZ at 90 VAC

How exactly would I hook up the Tellabs unit.  This looks like it might be the solution.  Not exactly a EE wiz here, but if it is not too difficult, I would probably donate this and the phone to my local Theatre.

[poplar1]

Just connect the output (two wires) to the phone but interrupted by a doorbell button in series with one of the two wires.

You might also want to put a regular 120 V incandescent light bulb in series with one side of the line. That way if the talk circuit in the phone is still connected, when they answer the phone you won't be shorting out the output of the ring generator.

You could also get fancy and hook it up to an interrupter that would send out ringing current for 2 second interval followed by 4 seconds of silence. Otherwise the guy behind the controls will have to time it.

[dsk]

Take a look at this
http://tinyurl.com/d4xabxb

dsk

[twocvbloke]

Oh yeah, I forgot about that Linksys thing, that would work...

[TelePlay]

Just connect the output (two wires) to the phone but interrupted by a doorbell button in series with one of the two wires.

You might also want to put a regular 120 V incandescent light bulb in series with one side of the line. That way if the talk circuit in the phone is still connected, when they answer the phone you won't be shorting out the output of the ring generator.

If you have a programmable digital light board, you can have your LD use one circuit on stage that would power a 120 relay to close for 2 seconds and then open for 4 seconds. Have that set up as a continuous loop on the light board. The next "go" on the light board would be to stop the cycle when the phone is picked up.

The Tellabs, or any other similar device would then be plugged into a standard wall power outlet with one wire connected to a relay switch terminal and then to the phone. The other Tellab's line would go directly to the phone. This way, the Tellabs unit would be providing a constant ring signal as long as it was plugged into the wall, as it was used in real life COs, and would send its ring signal to the telephone only when the relay was closed by the light board. The Tellabs unit would always be on but the phone would only ring when the light board powered the relay to close its SPST switch.

We tried doing this by powering the Tellabs unit on an off directly from a light board circuit but that did not work. Don't know why, current draw or something funny affecting the digital board.

In other words, a Radio Shack relay with a 120 VAC coil is being controlled by the light board program to provide an exact 2 second on and 4 second off ring cycle from the Tellabs 30HZ 90 VAC power to the phone's ringer.

If you don't want to use the light board, you can build an inexpensive timer circuit using a 555 IC that would open and close the relay in the desired cycle. By using the appropriate resistor/capacitor values in the circuit, you would have a digital interrupter to ring the phone by switching the Tellabs power to the phone on and off with a lower voltage relay coil but with a SPST relay switch capable of handling 90 VAC.

I built one to flash a 10 VAC light on a 565 phone for a business phone on stage and it worked perfectly. I ran the 555 circuit off of a 9 VDC adaptor and used a door bell transformer to get the 10 VAC needed for the light. The 555 circuit drops the voltage down to about 6 or 7 VDC so used a separate 10 VAC transformer to provide a constant voltage to the light (I used red and green to operate the phone and black and yellow to run the light so only needed one line cord from the set flat to the phone. Behind the flat, the two sets of wired were separated with the red and green being connected to a Teltone 4 line and the yellow and black to the 555 timer/power circuit in the booth. I used a simple SPST toggle switch to tune the 555 power on and another to engage the relay when the phone started to ring. Used a shorting 3rd toggle switch to make the light go full on once the phone was picked up. With the 555 circuit in the booth, I ran the 10 VAC to the stage down the Cat 5 cable I had installed to ring the phone. If you are going to use the light board, everything would have to be on stage. If you are going to build a 555 circuit, everything could be in the booth with a Cat 5 cable running to the stage or have it behind a flat or in the wings on stage to have some stagehand ring the phone from there. I prefer to ring the phone myself rather than run the change of a stage hand blowing one of my sound cues. But that's just me.

So, as with the light flasher, the same thing could be done for a phone ringer by using a relay capable of switching the 90 VAC generated by the Tellabs ring generator. Now that I've confused you, let me say there are many ways to do this. The easy ways are expensive, the cheaper ways time consuming.

[OldAussieGuy]

Hi
I concur with HarrySmith. Some years ago for my daughter's High School play I supplied a simple magneto generator directly wired to a phone onstage. With a little practice a stagehand was able to ring on-cue and it was very convincing. Any cheap magneto generator off ebay should do the job. Cheers