Telephone Power usage in Volts or whatever? ;-)

niceirishfella

hi,

I want to rig up a standard telephone to ring
(don't ask:D) - a standard eircom phone, not part of any system.
I want it to just ring as a prop for a play (if you must ask;)).......anyways, what power does a telephone work of? 3Volts, 6volts,12 or what, I have no idea but i need to get the right power supply for the job too.
Could you reccomend one?

Thanks,

NIF

Davy

Well the line is on 50dc all the time. I think then increases slightly when its actually ringing.

gnxx

I thought is was DC normally, but AC when ringing ....

From memory, 75V AC "rings a bell" (sorry couldn't resist)

niceirishfella

ahhh, ok.....thanks, and would a power supply be easy enough to get for this.........could you post me a link of a suitable power supply please?
I'm handy but useless on power/voltage stuff.

bushy...

You might be able to borrow a variable power supply or :


(Maplin or Peats should have these bits or you'd find them lying around)

Find a wall adaptor that puts out about 9 volts AC say 0.5 A

Next find a small transformer , any of the following types or thereabouts will do :

240v to 24v

120v to 12v

You might get one that has a "tapping " on the "high" side that allows 240v & 120v so it could be used in say here and the USA.



Anyway , connect the output from the wall adaptor to the "low" side of the transformer through a push button . ( see hi-tech scribble attached )

Then connect the "high" side of the transformer to the phone.

Needs to be put in a little box and output needs to be treated as if it was mains ( could kill people with dodgy hearts etc )

Put it in a box with a phone socket and get a phone extension cable to keep it safe and easy to use.

2 attachments , one is for 120v transformer , one is for more common 240-120-0


Note : "Wall transformer " thing has to be AC for this to work , will really just be another transformer-in-a-box .

Push button needs to be decent too, not those tiny things.

Car accessory places should have a (half!) decent pushbutton

niceirishfella

bushy... wrote: »

You might be able to borrow a variable power supply or :


(Maplin or Peats should have these bits or you'd find them lying around)

Find a wall adaptor that puts out about 9 volts AC say 0.5 A

Next find a small transformer , any of the following types or thereabouts will do :

240v to 24v

120v to 12v

You might get one that has a "tapping " on the "high" side that allows 240v & 120v so it could be used in say here and the USA.



Anyway , connect the output from the wall adaptor to the "low" side of the transformer through a push button . ( see hi-tech scribble attached )

Then connect the "high" side of the transformer to the phone.

Needs to be put in a little box and output needs to be treated as if it was mains ( could kill people with dodgy hearts etc )


2 attachments , one is for 120v transformer , one is for more common 240-120-0

awww, thanks for this and taking the time to do a diagram for me!

Joey the lips

I have easier solution, why dont you change the ring tone on a mobile to a old fashioned ring tone and just switch between tones to make it ring. Or else ring the phone of course!

niceirishfella

Joey the lips wrote: »

I have easier solution, why dont you change the ring tone on a mobile to a old fashioned ring tone and just switch between tones to make it ring. Or else ring the phone of course!

Thought about that, but there could be a network signal issue in the hall.
Also, it part of the set to have a REAL phone!:)
Thnaks all the same:pac:

danjo

Joey the lips wrote: »

I have easier solution, why dont you change the ring tone on a mobile to a old fashioned ring tone and just switch between tones to make it ring. Or else ring the phone of course!

The simple solution is often overlooked.

Good thinking Joey!

No reason why OP cannot have a real phone with a mobile beside it.

bushy...

danjo wrote: »

No reason why OP cannot have a real phone with a mobile beside it.

Signal problems in the hall , someone else may ring the number , it'll sound crap .

I'd gather this is a last minute thing , for the future get one made "properly" , will always be a useful device to have in a theatre.

Jonathan

gnxx wrote: »

I thought is was DC normally, but AC when ringing ....

From memory, 75V AC "rings a bell" (sorry couldn't resist)

From memory, I think this is correct.

You could always just get out a multimeter and check

brightspark

If you have the time/ability there is a circuit described here

http://www.techlib.com/electronics/telephone.html

I think the other posters are accurate with approx 70V being the figure I remember but it also was at 25Hz so the standard mains frequency makes a bell phone ring a bit quicker.


I used to ring the old ringer type (both a black one and a cream one) with a 55V supply from a transformer I took out of a discarded machine.


The previous guy in the group used a variable trafo, which was dangerous for two reasons.

1, The voltage is not isolated from the mains so there is a SERIOUS risk of electrocution

2, On one occasion the phone for some reason didn't ring and he turned up the supply to max when he didn't hear the ring only for the cable to burst into flames!

Everyday Electronics printed a circuit board for this very purpose many years ago (at least 15years), but I never got around to sourcing the components.


On the other hand I have been to many "professional" productions where it was obvious that the sound was coming from an offstage loudspeaker, so is it really so important (personally I'd prefer to have the sound come from the phone, or at least a discreetly located speaker close by).

But the audience in theatres are always suspending disbelief, people eating, drinking and smoking are all usually somewhat staged and no one really believes that real weapons etc are used, what I'm trying to say is that the audience is usually more forgiving about props and effects than they are about the acting/direction.

That said I was especially pleased when the young son of one of the cast asked, at the end of the show, to see the offstage "factory" that he heard whenever the door was opened.

And I did try to make an old analogue mobile appear to ring by using an fm transmitter to a radio in the actors pocket, unfortunately it wasn't powerful enough to overcome the interferance in the hall. I ended up getting the actor to leave the phone in his coat pocket which he hung up at the beginning of the scene and then located a speaker close to the hanger.


Lots of reading here

http://www.tkk.fi/Misc/Electronics/circuits/telephone_ringer.html

Stoner

how about a wireless doorbell that can record sound, that way you record the old fashioned phone ring tone or sound onto the the chime unit, place the chime unit beside or near to the prop phone and keep the wireless bell push off to the side or wherever the control room is, and you can push the door bell to make the phone ringing sound.

From what I can see you could have a straight through connection from your mobile phone to this device so you would get a very good quality door bell ringing sound recorded over a supplied cable, or else it has a built in microphone so you can place it beside an old phone and record the ringing (if they work or exist anywhere.)

Plus you can use it again for other stuff, just record the sound , like a dog barking, stick it in a pram for a baby crying, use it for jokes like farts etc:D.

http://doorchimesuk.co.uk/catalog/product_info.php?cPath=41&products_id=31

something like this is only 32 pounds and it's not dangerous, you could look around for something smaller this was the first google hit i got, but it looks perfect, they have another for 37 pounds, looks bigger but might have more kick.
they might be a bit big, but I'm sure you could work something out, the second one looks like you could stick a shade on it and pretend it was a lamp.
http://doorchimesuk.co.uk/catalog/product_info.php?cPath=22_25_26&products_id=32

I do not recommend that you play/work with the voltages you are talking about if you don't know what you are doing.

this is an out of the box soultion and one of the safer options, plus you can use it again if needed

Solair

DC Feeding conditions:

Exchange Voltage 44-56 V DC
Feed Bridges 2 X 400 ohm for AXE and some E10B exchanges.
Line Current 19 - 60 mA for AXE and E10B exchanges.
In some areas local loop carrier systems are in use. The line voltage on these varies between 15 V - 48 V depending on type.
Some E10 lines are fed using 40 mA constant current feed, these are lines which have 12kHz meter pulses. The constant current feed condition is only applied after dialling. (Now only used for pay phones)

Line Length

The maximum allowable line resistance is 1400 ohms, which is approximately 7.5 Km of 0.5mm conductor.

Ringing :

Frequency: 25 Hz
Voltage: 75 V rms on AXE exchanges. 40 V rms on each leg, out of phase on E10B exchanges.
Cadence: 0.4 s ON, 0.2 s OFF, 0.4 s ON, 2.0 s OFF or 0.375 s ON, 0,25s OFF, 0.375s ON, 2.0 s OFF repeated.
In some areas, local loop carrier systems are in use which have ringing voltages as low as 45 volts, 50 Hz ringing is commonly used by some PBXs. The voltage presented to the terminal equipment may be as low as 30 volts depending on line length and ringing impedance of the equipment.

Source: Eircom Network Interface Publication.

AXE refers to Ericsson AXE and E10 / E10B refers to Alcatel 1000-E10. These are the two types of digital PSTN/ISDN switches used by eircom.

About 50% are on E10 switches and the other 50% are on AXE.

In general, areas that were originally switched by older Ericsson Crossbar technologies, particularly ARF, were converted to Ericsson AXE. This means that for the most part, you'll find Ericsson Switches in high-density urban areas. (although this is not always the case)

While the Alcatel switches were rolled out in the early to mid 1980s, initially targeting areas with the worst phone service i.e. manually switched rural areas, and old step-by-step automatic areas in cities.

The two switching systems provide pretty much identical service.

You'll find a mixture of both types in Dublin depending on the area, while Cork City is entirely Ericsson switched.

Rural areas are mostly Alcatel E10, although there are some AXE too e.g. East Cork, parts of Galway, areas of the Midlands etc.

BTW: The type of exchange in use has absolutely nothing to do with DSL/broadband.

DSL is basically piggybacked onto the line, it doesn't have any interaction with the voice/ISDN exchange. It just lives in the same building.
Most, if not all, of eircom's DSL equipment's Alcatel gear.