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Vintage Telephony and Telecomms Vintage Telephones, Telephony and Telecomms Equipment |
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2nd Sep 2013, 9:04 pm | #1 |
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Will a US Telephone Bellset work in the UK?
Hi All
Quick question, will a US designated GPO Western Electric Bellset No. 1 work in the UK or were these specifically designed for the US market only - different voltages/amperes/Hz from the UK?? Just want to make sure if I buy a US version of the GPO Bellset No. 1 that it will work OK on the UK telephone system. Many thanks; |
2nd Sep 2013, 11:05 pm | #2 |
Heptode
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Re: will a US GPO Bellset No. 1 work in the UK?
Never heard of a 'US' version of a GPO 'Bellset No 1' . Do you mean a bellset that looks similar to a GPO Bellset No 1? A lot of bellsets look similar externally.
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3rd Sep 2013, 7:44 am | #3 |
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Re: will a US GPO Bellset No. 1 work in the UK?
Sorry it’s a more generalist question as to whether Bellsets used in the US are electrically the same as Bellsets used in the UK?
I’m assuming that they are universal and you can simply connect (following normal converting to the new style BT plug) any Bellset regardless of where it was manufactured and or destined for e.g. US, UK, AU, NZ… I just seem to remember reading somewhere that the US uses a different voltage compared to the UK phone network and whether this effected the component specification of the capacitor, ringer or induction coil for UK and US destined Bellset units? Thanks |
3rd Sep 2013, 11:22 am | #4 |
Dekatron
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Re: Will a US GPO Bellset No. 1 work in the UK?
If it's any help, I have two more modern U.S. telephones, a model 500 (Kellogg) and a model 2500 (ITT/Kellogg). Both work fine here in the UK on 25Hz 70V a.c. RMS giving that distinctive 'Rockford Files' or 'Kojak' sound - ringing cadence notwithstanding!
I think ringing voltage and frequency are pretty tolerant. Of course, your bellset was made when the UK ringing frequency was 16⅔ Hz, (one-third mains frequency), but, even so, I wouldn't've thought there was a problem. UK 16⅔ Hz bells work fine on 25Hz.
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3rd Sep 2013, 12:29 pm | #5 |
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Re: Will a US GPO Bellset No. 1 work in the UK?
It should work fine so long as the capacitor is OK. From tests of the examples in my collection I can say that as suggested by Russell, most of the early AE/Strowger bellsets circa 1909-1928 were designed for 20-25Hz but will ring on a broader range of frequencies. Likewise the WE and Kellogg bellsets. The difference to GPO/BPO practice was that the US bell motors had a higher DC resistance and impedance so the associated capacitor was 1mF rather than 2mF.
As far as I am aware the normal Bell and independent telecos practise was fairly much the same as the BPO, Australian PMG/APO and the NZPO as regards voltages for ringing and speech. The later, 1930s to 1960s AE, WE, NE, ITT and Kellogg phones that I have all ring happily on 16-30Hz 50-90VAC. Some will ring on 50Hz but sound dreadful. I have tried all these phones on two different British made PAX and also the Australian PSTN without any issues. However be aware that many of the phones (including auto) in the US were on shared or party line services with selective ringing. These bell motors were made to resonate and operate only at specific frequencies (16Hz, 20Hz, 25Hz, 33Hz, 50Hz and 66Hz from memory) and so will not respond to other frequencies. Andrew |
3rd Sep 2013, 6:32 pm | #6 |
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Re: Will a US Telephone Bellset work in the UK?
Russell & Andrew
Many thanks to you both for your feedback and especially Andrew for the very detailed information - which is exactly what I was looking for! Thanks guys |
3rd Sep 2013, 8:27 pm | #7 | |
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Re: Will a US GPO Bellset No. 1 work in the UK?
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4th Sep 2013, 1:19 pm | #8 |
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Re: Will a US Telephone Bellset work in the UK?
Regarding bell motors for specific frequencies, I do not have any myself but have learnt about them from descriptions and pictures in both printed and on-line documents. As far as I know, most of these motors were mechanically tuned with weights and springs so the armature and clapper arm look markedly different from the 'standard' bell motor. If the motor in your US made bellset looks similar to one in a GPO/BPO bellset then you can reasonably assume that it will work from 16Hz to 30Hz with the usual adjustments for armature travel. (There was one design, by Leich as I recall, that could be tuned by different combinations of coils and capacitors but I doubt that it was put in to wide service.)
I am not sure what phone you intend to use with the bellset but I can offer some safety advice gained from bitter experience. I take it that the phone will be an auto type with a dial. If the bellset was made by WE then the circuit is most likely the same as a PO Bellset No 1 (which was a CB circuit developed by WE in the 1890s). In this circuit the primary and secondary windings of the induction coil are used as part of the spark quench/suppression arrangement when dialling. The way that these windings are connected varies depending on the type of dial be it a No 8, a No 10 or possibly a No 24 (as used by ATM). If the phone is a WE or Kellogg type then the dial spring configuration can be different again. The problem is that the inductive spike generated when the pulsing springs open can go as high as 900V on a No 8 dial. This spike will sooner or later destroy the insulation on the induction coil. If the bellset was made by AE then it probably does not have an induction coil and the circuit has no provision for spark quench so the pulsing springs contacts will eventually burn away if used on a 'modern' system as well as producing distorted pulses. The solution is to add a 0.1-0.5mF (250V greencap) capacitor and a 49 ohm, 1/2W resistor in series across the pulsing springs contacts as a spark quench. Make sure that you wrap these in plastic insulation (tape or heat shrink). If you keep it small the combination should tuck in behind the dial and does not require any permanent modification to your phone. The other potential problem concerns the type of transmitter on the phone. A PO No 13 should be OK but if it is an old solid-back type then it can quickly burn out if the line current goes much over 25mA. A good precaution is to put a 330 ohm 5W resistor in series with the line. This will not affect ringing and will only slightly reduce speech volume. (The addition of a resistor was standard Australian PMG practice on short lines before the introduction of regulators.) Andrew |
4th Sep 2013, 3:56 pm | #9 | |
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Re: Will a US Telephone Bellset work in the UK?
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Is this the spring you are referring to? (see pic) |
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5th Sep 2013, 1:47 am | #10 |
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Re: Will a US Telephone Bellset work in the UK?
No that is a bias spring designed to stop bell tinkle when the receiver was lifted and/or during dialling. The idea was to hold the clapper lightly against the gong that it would otherwise be driven to when the capacitor discharged. The spring was not strong enough to resist movement of the armature when the bell motor was driven with AC during ringing. I am fairly sure that the bell motor pictured would respond to a 16-30Hz signal. The same bias spring idea was used in later WE 302 and Kellogg phones although the shape of the bell motor was different.
I have seen a similar bias spring fitted to bell motors in early (pre 1925) No 1 bellsets however it was a compromise design that had a flaw. In this design one end of the spring was looped through a lug on the armature and the other end was tied to a short (cotton/silk ?) thread. The thread was then passed through a hole in a bolt fitted to the right hand pillar in the frame. By turning the bolt the thread wrapped around the bolt to alter the tension on the armature. The flaw was that the thread would deteriorate and break. The spring would then bounce around often jamming the armature. Later bell motors were not fitted with this spring arrangement but a hole for the bolt was still drilled in the pillar. Andrew |
5th Sep 2013, 2:03 am | #11 |
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Re: Will a US Telephone Bellset work in the UK?
The following links give more info on harmonic ringing in the US context for those who may be interested.
Andrew http://navysalvage.com/partyringers.html http://www.classicrotaryphones.com/f...p?topic=8477.0 http://oldphoneguy.com/images/oldtex22bw.pdf http://www.google.com/patents/US1014125 http://www.telephonearchive.com/phones/kg/kg1000.html http://www.bobsoldphones.net/Pages/S...ergCarlson.htm |
7th Sep 2013, 1:03 pm | #12 |
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Re: Will a US Telephone Bellset work in the UK?
With more than two parties sharing the line, how do you deal with seizing it?
On a UK shared service line, if my memory serves me correctly, each party had a button which -- if the other party was not already using the line -- had to be pressed before making a call and which shorted one leg of the line to earth, to give a dial tone and start your meter running. (The other party's switch would earth the opposite leg and start their meter running.) Multiplexing up to 10 phones on the same line using one of five ringing frequencies and two connection schemes is an interesting idea; but without a precisely-tuned oscillator in each phone, how do you indicate to the exchange who is going to be paying for the call?
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7th Sep 2013, 1:41 pm | #13 | |
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Re: Will a US Telephone Bellset work in the UK?
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28th Apr 2015, 8:34 am | #14 |
Heptode
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Re: Will a US Telephone Bellset work in the UK?
I believe the most are told earlier in this thread. UK ringers was traditionally made for 90V at 25 Hz, but not tuned to accept only 25Hz. North American ringers was equal, but optimized for 20Hz. Both countries could use exchanges with different ringing frequency using the same ringer. US sometimes used 30Hz on PBX's. In North America the ringer motors was redsigned to use less power, and they got typical higher resistance coils and just 1/2 microfarad capacitors. At one point UK started with master socket, and a common 1.8 microfarad capacitor in each house. All these ringer motors are pretty universal and should work in most countries. The North American ringers got a pretty strong bias springs (forsing the hammer to rest at one side) to prevent tinkeling when other phones dialed on the same line, this may need adjustment when the ringer signal becomes weak. In addition North America used tuned ringers, most of them does not work on a regular line. Both countries has used grounding of one side of the ringer circuit, this extra cord should just be isolated from ground, and bonded to the other line.
To reduce high load some use to add resistors in series with old ringers, this will usually not be needed on a North American phone. dsk |