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uk.telecom.voip (UK VOIP) (uk.telecom.voip) Discussion of topics relevant to packet based voice technologies including Voice over IP (VoIP), Fax over IP (FoIP), Voice over Frame Relay (VoFR), Voice over Broadband (VoB) and Voice on the Net (VoN) as well as service providers, hardware and software for use with these technologies. Advertising is not allowed.

GPO Telephone 332 Bell Issues



 
 
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  #1  
Old September 30th 09, 09:00 PM posted to uk.telecom,uk.telecom.voip
E27002
external usenet poster
 
Posts: 7
Default GPO Telephone 332 Bell Issues

Can anyone advise on this issue and how to fix it?

I have in my possession a GPO Telephone 332. In 2001 I used it in
Edinburgh plugged into a standard BT master socket. AFAIR it worked
just fine.

The 'phone is converted, i.e. it has a 3.3k resistor in series with
its bell. Just recently I tried to utilize at my home here in the US
on my VoIP setup.

My internet acess is thru my Cable company. The Cable interface box
is connected to a D-Link router. It in turn is connected to a UK
Standard Linksys/ATA router. The first RJ11 output port on the
Linksys is connected to one pair of a Cat5e cable that runs to my
Study. The run is eighty feet max.

The Cat5e pair is terminated thru a wall in my study with a standard
BT master outlet. When I plug my GPO 332 into said master outlet, I
have dial tone. Clearly I cannot make calls. However, receiving them
is also an issue. The bell in the 332 barely rings. The bell just
"tinkles" a little.

Is this because the ATA does not provide enough "juice"? Could the
bell have deteriorated during its eight years of disuse?

Thanks
  #2  
Old September 30th 09, 09:42 PM posted to uk.telecom,uk.telecom.voip
Graham.
external usenet poster
 
Posts: 876
Default GPO Telephone 332 Bell Issues



"E27002" wrote in message
...
Can anyone advise on this issue and how to fix it?

I have in my possession a GPO Telephone 332. In 2001 I used it in
Edinburgh plugged into a standard BT master socket. AFAIR it worked
just fine.

The 'phone is converted, i.e. it has a 3.3k resistor in series with
its bell. Just recently I tried to utilize at my home here in the US
on my VoIP setup.

My internet acess is thru my Cable company. The Cable interface box
is connected to a D-Link router. It in turn is connected to a UK
Standard Linksys/ATA router. The first RJ11 output port on the
Linksys is connected to one pair of a Cat5e cable that runs to my
Study. The run is eighty feet max.

The Cat5e pair is terminated thru a wall in my study with a standard
BT master outlet. When I plug my GPO 332 into said master outlet, I
have dial tone. Clearly I cannot make calls. However, receiving them
is also an issue. The bell in the 332 barely rings. The bell just
"tinkles" a little.

Is this because the ATA does not provide enough "juice"? Could the
bell have deteriorated during its eight years of disuse?

Thanks


My experience is an ATA does not provide nearly as much ringing
current as my BT line.
Try reducing the value of the 3k3 resistor, try shorting it out completely.
The reason it is there in the first place is to raise the impedance of the
bell so that parallel modern HI-Z ringers get a fair share of the available
current. As this is likely to be the only phone on the ATA port that won't
be an issue.

--
Graham.

%Profound_observation%


  #3  
Old October 1st 09, 09:47 PM posted to uk.telecom,uk.telecom.voip
Dave Higton
external usenet poster
 
Posts: 77
Default GPO Telephone 332 Bell Issues

In message
E27002 wrote:

Can anyone advise on this issue and how to fix it?

I have in my possession a GPO Telephone 332. In 2001 I used it in
Edinburgh plugged into a standard BT master socket. AFAIR it worked
just fine.

The 'phone is converted, i.e. it has a 3.3k resistor in series with
its bell. Just recently I tried to utilize at my home here in the US
on my VoIP setup.

My internet acess is thru my Cable company. The Cable interface box
is connected to a D-Link router. It in turn is connected to a UK
Standard Linksys/ATA router. The first RJ11 output port on the
Linksys is connected to one pair of a Cat5e cable that runs to my
Study. The run is eighty feet max.

The Cat5e pair is terminated thru a wall in my study with a standard
BT master outlet. When I plug my GPO 332 into said master outlet, I
have dial tone. Clearly I cannot make calls. However, receiving them
is also an issue. The bell in the 332 barely rings. The bell just
"tinkles" a little.

Is this because the ATA does not provide enough "juice"? Could the
bell have deteriorated during its eight years of disuse?


With a 3k3 resistor in series with the bell, I'm astonished it
rings at all.

Dave
  #4  
Old October 5th 09, 08:36 AM posted to uk.telecom,uk.telecom.voip
Russell W. Barnes
external usenet poster
 
Posts: 2
Default GPO Telephone 332 Bell Issues


"Owain" wrote in message
...

I suppose it's also possible that the conversion retained the original
bell capacitor, which is now faulty.

Owain


All this business about removing the original capacitor and inserting a 3k3
resistor is fine: I've never had any problems with conversions, but I
undertook some experiments with bell-motors and capacitors, and I'm
convinced that: not only was the capacitor used to isolate the bell (as well
as a DC receiver block and part of the dial spark suppression cct with the
resistive windingf in the ASTIC), but that there is an element of resonance
there as well.

Tests on an Ericsson mining telephone type N1087 using a linesman's
test-instrument providing 25Hz at an unloaded 50V (and limited to 15mA at
16V into a 1k1 resistor), I found that the bell alone drew 8.6mA at 35.6V.

With the 2uF capacitor in series, the current was 9.8mA with 32.8V dropped
across the bell and 46.5V dropped across the capacitor.

The Z of the bell works out at 4240 Ohms, and the inductive reactance (from
the 1000 Ohm DC resistance) works out at +j4017.

The capactitve reactance of the 2uF bell capacitor works out as -j3183

I've conducted similar experiments on type 700 series telephones in the
past, and the results have been similar. I guess with a constant-voltage
25Hz supply the increase in current at near-resonance would be greater, my
test-instrument supply being rather 'saggy'.

The point I am making is this: Were telephones fitted with a bell designed
to resonate (or near-resonate) at the ringing frequency, or is this just
co-incidental?

And:

Might a capacitor included in the OPs bell cct improve matters by wringing
(no pun intended) as much out of the bell current as possible?
--
Regds,

Russell W. B.
http://www.huttonrow.co.uk
http://www.flickr.com/photos/russell_w_b

Please replace appropriate text with punctuation to reply!




  #5  
Old October 5th 09, 12:58 PM posted to uk.telecom,uk.telecom.voip
John Weston
external usenet poster
 
Posts: 108
Default GPO Telephone 332 Bell Issues

In article , ""Russell
W. Barnes"" wrote:



The point I am making is this: Were telephones fitted with a bell designed
to resonate (or near-resonate) at the ringing frequency, or is this just
co-incidental?

And:

Might a capacitor included in the OPs bell cct improve matters by wringing
(no pun intended) as much out of the bell current as possible?


You are probably right, since the bistable ringers (two coils, with the
long ringer hammer going down between them to the gongs) worked best at
the original 16 2/3Hz and sounded terrible on 25Hz. I remember falling
back on the traditional motor generator ringers rather than try to do it
with the electronics of the day. Half-wave rectified 50Hz was useless on
most installations.

--
John W
I you want to mail me, replace the obvious with co.uk twice
  #6  
Old October 5th 09, 01:22 PM posted to uk.telecom,uk.telecom.voip
russell_w_b
external usenet poster
 
Posts: 1
Default GPO Telephone 332 Bell Issues

On 5 Oct, 12:58, John Weston wrote:
In article , ""Russell

W. Barnes"" wrote:

The point I am making is this: *Were telephones fitted with a bell designed
to resonate (or near-resonate) at the ringing frequency, or is this just
co-incidental?


And:


Might a capacitor included in the OPs bell cct improve matters by wringing
(no pun intended) as much out of the bell current as possible?


You are probably right, since the bistable ringers (two coils, with the
long ringer hammer going down between them to the gongs) worked best at
the original 16 2/3Hz and sounded terrible on 25Hz. *


John,

Thanks for the reply. I have just tested a Magneto Generator No:26A
(ex-Type 'F' field-telephone) and found it delevers a little more
'whoomph' than the Linesman's Telephone 704 I was using (batteries not
up to scratch?). I can get 60mA into a 1200 Ohm resistor, and
vigorous turning gives an O/C voltage of 90V and a S/C current of
100mA, so I'm guessing its impedance was designed to match - more-or-
less - a 1000R bell-motor; maximum power-transfer, and all that... I
shall undertake further tests.

Trouble is, I'll need a steady rotation to keep a stable 16 2/3 Hz! I
also have one of those REN extenders which I shall look at with a view
to providing an experimental ring-current source (probably 25Hz,
though).

When, and why, was sub-cycle 1/3 mains-frequency replaced with 1/2
mains-frequency for ringing, and were bell-motors produced after this
date re-designed for the higher frequency?
--

Regds,

Russell W. B.
http://www.huttonrow.co.uk
http://www.flickr.com/photos/russell_w_b

  #7  
Old October 5th 09, 02:44 PM posted to uk.telecom,uk.telecom.voip
John Weston
external usenet poster
 
Posts: 108
Default GPO Telephone 332 Bell Issues

In article 0aeb1288-1053-4f86-8040-ecf60c0aa978
@e18g2000vbe.googlegroups.com, "russell_w_b" wrote:

When, and why, was sub-cycle 1/3 mains-frequency replaced with 1/2
mains-frequency for ringing, and were bell-motors produced after this
date re-designed for the higher frequency?


The ring and tone generator was 3-phase, providing 3-phase ringing
cadence as well, via cam-driven contacts (400ms on, 200ms off, 400ms on
2s off with the next "phase" starting after the last 400ms on and then
once more before restarting the cycle) The 16 2/3Hz ring current
frequency is a third of 50Hz, but I don't know if this is of any
significance...

I don't know exactly when it went to 25Hz, probably when it eventually
was electronically generated? I see 16 2/3 was a common frequency used
on early railways, so it could have come from there. I could look it up
in Atkinson, but that's likely to give the how rather than the why.

--
John W
I you want to mail me, replace the obvious with co.uk twice
  #8  
Old October 5th 09, 09:49 PM posted to uk.telecom,uk.telecom.voip
Gaius
external usenet poster
 
Posts: 91
Default GPO Telephone 332 Bell Issues

John Weston wrote:
In article 0aeb1288-1053-4f86-8040-ecf60c0aa978
@e18g2000vbe.googlegroups.com, "russell_w_b" wrote:

When, and why, was sub-cycle 1/3 mains-frequency replaced with 1/2
mains-frequency for ringing, and were bell-motors produced after this
date re-designed for the higher frequency?


The ring and tone generator was 3-phase, providing 3-phase ringing
cadence as well, via cam-driven contacts (400ms on, 200ms off, 400ms on
2s off with the next "phase" starting after the last 400ms on and then
once more before restarting the cycle) The 16 2/3Hz ring current
frequency is a third of 50Hz, but I don't know if this is of any
significance...

I don't know exactly when it went to 25Hz, probably when it eventually
was electronically generated? I see 16 2/3 was a common frequency used
on early railways, so it could have come from there. I could look it up
in Atkinson, but that's likely to give the how rather than the why.


As I remember, this came about when the "New" PMBXs like the 3+12 came
in (plastic rather than wooden cases!). The ring current was obtained
from a power unit which had a cheap, simple 1/2 frequency divider
working off the mains. 16 2/3Hz was too difficult to derive, for what
was a low-cost installation.

I've no idea when/why 25Hz became the PSTN primary standard, though.
  #9  
Old October 7th 09, 06:38 PM posted to uk.telecom,uk.telecom.voip
E27002
external usenet poster
 
Posts: 7
Default GPO Telephone 332 Bell Issues

On Oct 6, 4:48*am, Bodincus wrote:
Gaius:



John Weston wrote:
In article 0aeb1288-1053-4f86-8040-ecf60c0aa978
@e18g2000vbe.googlegroups.com, "russell_w_b" wrote:


When, and why, was sub-cycle 1/3 mains-frequency replaced with 1/2
mains-frequency for ringing, and were bell-motors produced after this
date re-designed for the higher frequency?


The ring and tone generator was 3-phase, providing 3-phase ringing
cadence as well, via cam-driven contacts (400ms on, 200ms off, 400ms
on 2s off with the next "phase" starting after the last 400ms on and
then once more before restarting the cycle) The 16 2/3Hz ring current
frequency is a third of 50Hz, but I don't know if this is of any
significance...


I don't know exactly when it went to 25Hz, probably when it eventually
was electronically generated? *I see 16 2/3 was a common frequency
used on early railways, so it could have come from there. *I could
look it up in Atkinson, but that's likely to give the how rather than
the why.


As I remember, this came about when the "New" PMBXs like the 3+12 came
in (plastic rather than wooden cases!). The ring current was obtained
from a power unit which had a cheap, simple 1/2 frequency divider
working off the mains. 16 2/3Hz was too difficult to derive, for what
was a low-cost installation.


I've no idea when/why 25Hz became the PSTN primary standard, though.


Because dividing a frequency in half requires only some cheap, durable
and reliable electronics (diodes) but dividing a frequency by three
requires expensive and subject to wear an tear electromechanical devices?
BTW, while interesting for us geeks, can you please remove
uk.telecom.voip from your discussion?
Thanks

Point taken! However, with regards to my original query, VoIP is
relevant. If my ATA is not providing current at the right frequency,
that may be part of the issue with the bell in my telephone. I am
going to check if the capacitor is still in the circuit. But, based
on the forgoing, trying to use a 332 with an ATA may not be smart.
Perhaps a 200 series ‘phone with a separate electronic audible device
is a better solution

  #10  
Old October 7th 09, 09:35 PM posted to uk.telecom,uk.telecom.voip
Russell W. Barnes
external usenet poster
 
Posts: 2
Default GPO Telephone 332 Bell Issues




"E27002" wrote in message
...

8------------------

'Perhaps a 200 series ‘phone with a separate electronic audible device
is a better solution.'


Could you obtain an 8700 series telephone (they sometimes pop up on eBay),
one of the last dial-types, like a BT 'Yeoman' (the brown, later variant of
the 746)? They have a 4k ringer rather than a 1k one. AFAIK the mounting
screw-holes on the bell magnet yoke are the same, but if not, replacing the
2 x 500R bobbins of your 332 with the 2 x 2k bobbins is simple enough.

Even a pair of 500R bobbins from an old 706 might be better than your
existing ones. Have you tried adding a 1u8 or a 2u capacitor in series with
the bell to see if it makes any difference? Judicious adjustment of your
gongs might make a difference as well. Granted, UK telephones might not be
so ready to obtain in the US.

One of the things that made the ringers sound so pleasing on 16 2/3 Hz was
the non-sinusoidal waveform whereby the 'peaky' crests exacerbated the pull
on the polarised armature. I know on some modern exchanges that the ringing
supply is a quasi-sinusoidal voltage made up from digitally stepped pulses.
--
Regds,

Russell W. B.
http://www.huttonrow.co.uk
http://www.flickr.com/photos/russell_w_b

Please replace appropriate text with punctuation to reply!


 




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