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GPO Telephone 332 Bell Issues

 
 
E27002
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      09-30-2009
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
 
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Graham.
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      09-30-2009


"E27002" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
> 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%


 
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Dave Higton
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Posts: n/a
 
      10-01-2009
In message <(E-Mail Removed)>
E27002 <(E-Mail Removed)> 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
 
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Owain
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      10-01-2009
On 1 Oct, 21:47, Dave Higton wrote:
> With a 3k3 resistor in series with the bell, I'm astonished it
> rings at all.


Original in the old Plan Whatever arrangement there could be up to 6
phones with series connected bells, so any phone could have up to 5k
(5 bells x 2 solenoids x 500R per solenoid) in series with its bell.

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

Owain

 
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John Weston
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      10-05-2009
In article <(E-Mail Removed) >, ""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
 
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russell_w_b
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Posts: n/a
 
      10-05-2009
On 5 Oct, 12:58, John Weston <(E-Mail Removed)> wrote:
> In article <(E-Mail Removed) >, ""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

 
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John Weston
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Posts: n/a
 
      10-05-2009
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
 
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russell_w_b
Guest
Posts: n/a
 
      10-05-2009
On 5 Oct, 14:44, John Weston <(E-Mail Removed)> wrote:

8><--------------------------
>*I could look it up
> in Atkinson, but that's likely to give the how rather than the why.
>


I shall look in my 'Atkinson' when I get home. It was written in
1947, and I have a feeling it still refers to 16 2/3 Hz. Poole's
'Telephone Handbook' refers to 16 2/3 Hz, and it is slightly older
than 'Atkinson'.

Interestingly, I can find no reference (in Atkinson) to resonance in
bell circuits, although a good explananation of polarised ringing is
given.
--

Regds,

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

 
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Gaius
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Posts: n/a
 
      10-05-2009
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.
 
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Bodincus
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Posts: n/a
 
      10-06-2009
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

X-Post and FUs set
--
Bodincus - The Y2K Druid
----------------------------
Law 42 on computing: Anything that could go wron% $
$: Access Violation - Core dumped
 
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