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Old 3rd Dec 2011, 2:24 pm   #1
macca64
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Default Virgin line voltages, Re: Bellset 26/31.

Hello all,

Is there anyone out there who knows the voltage I should expect to find on my Virgin telephone line in standby and ringing?

Unfortunately Virgin's helpline was not able to help with this enquiry. I am hoping to convert the 31 to a 26 bellset for use on my telephone line and I am led to believe it is voltage critical.

I am a novice to this so I have many questions to follow!
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Old 3rd Dec 2011, 6:25 pm   #2
val33vo
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Default Re: Virgin line voltages, Re: Bellset 26/31.

I should imagine Virgin would use the bog standard line voltage of 50V, after all supermarkets sell 'phones these days and they have to all be compatible.

Ringing voltage would probably be around 100volts AC, quite frankly I don't think you have an issue here.

The problem you have is that it is designed to be used in a hardwired system and the bells are designed to be all connected in series and switched out of circuit when a telephone handset is lifted.

Likely problems of trying to connect a bellset like this are bell tinkle if you still have loop disconnect dialling telephones and broadband problems, ADSL uses a high frequency and any extension or 'phone wiring before the filter can set up standing waves which will cause errors or complete loss of service.

Regards,

val33vo.
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Old 3rd Dec 2011, 10:59 pm   #3
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Default Re: Virgin line voltages, Re: Bellset 26/31.

Quote:
Originally Posted by val33vo View Post
I should imagine virgin would use the bog standard line voltage of 50V, after all supermarkets sell phones these days and they have to all be compatabile

ringing voltage would probably be around 100volts AC, quite frankly I dont think you have an issue here



regards

val33vo
I was involved in the early days of Smartboxes; the way to get indirect 'phone services over an alternate carrier (i.e Mercury). One of the problem areas involved System X exchanges which presented 60V at the equipment side and the 'handset off' voltage was too high for the equipment that see the lift off condition to recognise. Can't comment on incoming voltages as these caused no problems to this kit.
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Old 3rd Dec 2011, 11:06 pm   #4
AndiiT
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Default Re: Virgin line voltages, Re: Bellset 26/31.

Hi,
Nominal line voltage from any supplier is 50 Volts DC with the B leg negative with respect to the A leg.

In practice BT lines are around 48 Volts across the A and B leg and Virgin Lines are 42 Volts.

Note that the A leg is NOT at true earth potential, on either system, but sits around 3 to 5 Volts positive with respect to true earth.

Ringing current on both suppliers is 75 Volts AC at 25 Hertz.

Anything that measures less than around 38 Volts across the line pair (when on hook/idle) should give cause for concern.

Regards
Andrew
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Old 4th Dec 2011, 12:40 am   #5
russell_w_b
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Default Re: Virgin line voltages, Re: Bellset 26/31.

Quote:
Originally Posted by AndiiT View Post

Anything that measures less than around 38 Volts across the line pair (when on hook/idle) should give cause for concern.
Certainly should on a subs' line (48 - 50V nominally - sometimes about 4 - 6V between A-leg and non-telecom earth). All SHF SDH link equipment I've worked with observes this 48 - 50V protocol, so I guess it's a standard telecom thing - can't open BT SiNET at the moment to be more precise

But... Our works INDeX system measures 36V on analogue ports with no problems whatsoever. The digital ports measure about 39V, so being possible to poke around in a junction box and tell the difference with nothing more than a metimulter.

Furthest analogue port from our switch is about 1.5km, and no problems. As for ringing, as low as 23V RMS ringing will drive sufficient current through a master LJU and a couple of modified (3k or 3k3 resistor-included) bell instruments and an 8782 4k bell-motor without fail.
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Old 4th Dec 2011, 12:48 am   #6
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Default Re: Virgin line voltages, Re: Bellset 26/31.

I think the OP has asked the wrong question. Perhaps he should have asked "How do I wire a bellset 26/31 for use on a plug and socket system?" Line voltages and ringing voltages have little if anything to do with it.
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Old 4th Dec 2011, 6:41 pm   #7
macca64
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Default Re: Virgin line voltages, Re: Bellset 26/31.

Many thanks to you all for your input,my standing line voltage is 42v.I have wired the bells with a 3k resistor and and have a resistence of 4k on the bell circuit.I am sure Graham is right I just seem to be missing a trick,please bear with me as I am determined to crack it,with help.

Thankyou all .Regards Tony
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Old 10th Dec 2011, 4:08 am   #8
Chipmunk
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Smile Re: Virgin line voltages, Re: Bellset 26/31.

It depends what area you are in. I know in Southampton, ex Videotron, then CWC, then NTL now Virgin lines, (wow, all that history in a few short years) are 36 volts on hook. The batteries in the cabinets are actually 48v but for some reason the line voltage is only 36. I know this caused me a few problems with Renown PBXs 'back in the day'. I suspect more modern virgin installations likely use 48-50v the same as everyone else.

But as others have said, the line voltage will have little effect on a strowger era piece of equipment like this bellset, (within reason). They were often used by the GPO on 24v PBX lines, 22v CB lines, 50v or (on siemens s17 systems) automatic lines without modification

Last edited by Chipmunk; 10th Dec 2011 at 4:09 am. Reason: That smiley always gets me...
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