Old style UK phone to ring

[kerry davies]

Always handy to have and they seem cheaper now than ever is a Linesman's Field Telephone 704/704B.

[gyro_gearloose]

Our prompt desk has got 3 phones sockets and an adjustable ringer. At first no one though it worked, and now everyone just uses qLab :)

[dbuckley]

In true Blue Peter style, here's one I made earlier

 

Ha!

 

I'm up to the Mk 3 version of my ringer design, and it seems to do everything right. It's even got a user interface to se the DMX address. There's some info and background of the Mk 2 here but that one used an OLD BT ringing transformer, so it wasn't the complete design. The Mk 3 generates the ringing current on-board. I've yet to document the Mk 3, but if anyone wants to build one I'm sure I can sort out the necessary files.

 

Or if you wish to be pedantic, 16.66666 Hz

 

My current ringer can alter the frequency under DMX control, and it really doesn't sound that much different even with a very wrong frequency.

 

I added the variable frequency feature to try to simulate the uneven frequency of a hand-cranked magneto for an old period piece, and it worked a bit, but it was a lot less impressive than I'd hoped.

[thelxbloke]

I haven't tried this but came across it a while ago. Uses sound files for the cadence and 100v line amp or standard amp and transformer.

 

Ch Sound Design Ringmaster

 

[boatman]

For those who may be interested there's a great documentary on BBC iPlayer about the history of the landline telephone here:

 

http://www.bbc.co.uk/iplayer/episode/b08mp2l8/timeshift-series-17-3-dial-b-for-britain-the-story-of-the-landline

[Ynot]

Or if you wish to be pedantic, 16.66666 Hz http://www.blue-room.org.uk/public/style_emoticons/default/blink.gif

Brian

I seem to recall the standard ringing frequencies as 17 or 25Hz from the various signalling units we used to use (and probably still do in places).

 

I have a couple knocking around somewhere - one commercial unit that delivered the UK and US cadences, the other was a home-brew I knocked up on a timber backboard from an old sig unit and some simple push-buttons...

[Lamplighter]

The frequency was derived from a mains driven motor-generator, the ringer output being 1/3 of the input frequency. This was chosen as being close to the nominal 17 Hz of a manual ringer which all the bell systems were tuned for, and the subscribers accustomed to.

 

Brian

[boatman]

A retired GPO engineer friend (yes really GPO and not BT!) told me that the frequency was changed to 20Hz when ring tone cadence was introduced. The ring tone was electronically generated rather mechanically and 400mS on period is 8 full cycles of 20Hz compared to 6.666667 cycles of 16.66667Hz.

[Ynot]

A retired GPO engineer friend (yes really GPO and not BT!) told me that the frequency was changed to 20Hz when ring tone cadence was introduced. The ring tone was electronically generated rather mechanically and 400mS on period is 8 full cycles of 20Hz compared to 6.666667 cycles of 16.66667Hz.

 

Interesting.

I'd not heard that (and it was still the GPO when I started in '78... :) ) although I do believe that the ring TONE (ie the audio you hear in the handset) cadence seldom actually matches up with the actual ringing signal to the bellsets. That MAY have changed in recent years considering changes to the way signalling works.

[Lamplighter]

The ring tone was fed from the same generator as ringing current, they were each generated as 3 phases and there was no sycronisation in the distrbution of the phases, so on any call it would be random as to which ring tone and ringing currentwre used. I believe that the use of higher

( 20 and 25 Hz) frequencies came about with the expansion of the larger Automatic) private axchanges in the 1960's. 25 Hz was commonly derived from the mains supply using saturable reactor transformers.

[kerry davies]

Pedants'R'Us assure me, Tony, that I joined Post Office Telecommunications in '74 which it became from GPO in '69. We knew it as P.O. Telephones. (Yesterday I couldn't spell tellickermoonickayshuns tecknishun, today I are one!)

 

Not sure about today but the old PMBX 1Atype board was often used in prompt corner. Like everything in PO it had a number which escapes me now. They would mostly all have a ringer even if it were not wired up.

 

When I started there were still a few old timers around with "notched ears" from having been caught by ringing current up amongst the open wires. I had a couple of shocks and it was impossible not to jerk one's head thereby turning the open copper wire into impromptu cheese slicers.

 

Ringing was a 25 cycles a.c, 60 volt supply and Converters Ringing were used on PMBX switchboards to supply it. The more bells, the bigger the unit and a Converter Ringing 9A which went with Planset 625 to provide external extensions on Plan 107 and Plan 105 "secretarial" type systems would be useful for our needs.

[Ynot]

Pedants'R'Us assure me, Tony, that I joined Post Office Telecommunications in '74 which it became from GPO in '69. We knew it as P.O. Telephones.

OK, smart-A :D

Whilst it was indeed PO Telecoms, we all still referred to it as the GPO ... :)

(Yesterday I couldn't spell tellickermoonickayshuns tecknishun, today I are one!)

Oh yes... :)

When I started there were still a few old timers around with "notched ears" from having been caught by ringing current up amongst the open wires. I had a couple of shocks and it was impossible not to jerk one's head thereby turning the open copper wire into impromptu cheese slicers.

Almost as bad was wiring on the MDFs and catching ring current causing a jerk of the hand to scrape along the adjacent 200pr termination block, giving multiple tram-lines of bleeding scrapes across the back of the hand... (Because we ALWAYS donned those protectors, hand 1A, didn't we..... :o )

 

[boatman]

.

.

Almost as bad was wiring on the MDFs and catching ring current causing a jerk of the hand to scrape along the adjacent 200pr termination block, giving multiple tram-lines of bleeding scrapes across the back of the hand... (Because we ALWAYS donned those protectors, hand 1A, didn't we..... :o )

 

When I joined the BBC in the 60s at Television Centre, I worked with a wireman who always stripped the twisted pairs with his teeth when wiring the MDFs. Being a naive young man at the time, I asked him once if it hurt and he said "Only when there's ring tone on the line!".

[Ynot]

When I joined the BBC in the 60s at Television Centre, I worked with a wireman who always stripped the twisted pairs with his teeth when wiring the MDFs. Being a naive young man at the time, I asked him once if it hurt and he said "Only when there's ring tone on the line!".

:D

 

I think we all did that one time or another - though I stopped early on when I chipped the corner of a tooth and fell back on the shiny pair of Lindstrom pliers wiring.

Either way, if you were running more than 2 or 3 jumpers at a time, it DID start to smart a little stripping by teeth... :)

[Don Allen]

This document ITU VARIOUS TONES USED IN NATIONAL NETWORKS (ACCORDING TO ITU-T RECOMMENDATION E.180)(03/1998) should clarify ring tones ?

 

United Kingdom of Great Britain and Northern Ireland FREQUENCY in HZ CADENCE in seconds

Busy tone - 400 0.375 on 0.375 off

Congestion tone - 400 0.4 on 0.35 off 0.225 on 0.525 off

Dial tone - 50//350+440 continuous

Number unobtainable tone - 400 continuous

Pay tone - 400 0.125 on 0.125 off

Payphone recognition tone - 1200/800 0.2 on 0.2 off 0.2 on 2.0 off

Ringing tone - 400+450//400x25//400x 16 2/3 0.4 on 0.2 off 0.4 on 2.0 off

 

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