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Old 4th Mar 2007, 3:29 am   #1
trevwgb
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Join Date: Feb 2007
Location: Haywards Heath, West Sussex, UK.
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Question Bell Set No. 20

Hi all
For starters can I thank those who kindly responded to my previuos Q. re a speaker for the AR88 - the answers were most helpful and educational for a novice. It was aquiring the AR88 which got me to join this discussion forum, but I now see that some of you are also telephone experts. I have a Bell Set no. 20 in good condition which currently sits on my wooden stereo cabinet as an ornament. I have the cicuit diagram and some stuff from the internet but could could do with more info. Am I correct in thinking that the idea is that this device rings when there is an incoming call and that the call can then be directed to one of the attached phones ( i.e. main phone or extension ). If this is correct, is it possible to wire it into the current BT line as I have successfully done with my Telephone no. 332? Also the Bell set appears to use a battery - what sort of battery is this?
Any brilliant idea gratefully received
Regards
Trev
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Old 4th Mar 2007, 1:35 pm   #2
Nickthedentist
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Default Re: Bell Set No. 20

Some info here, Trev: http://www.britishtelephones.com/bellst20.htm

Nick.
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Old 4th Mar 2007, 4:56 pm   #3
jim_beacon
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Default Re: Bell Set No. 20

Yes, the bellset can be connected to a standard BT line.

The Bellset 20 allows for exchange to main, exchange to extension, main to extension and an enquiry call from main to extension, with the exchange held.

There is a link which can be set to allow privacy on extn to exchange calls (otherwise the main phone can listen in).

I believe you also need an external PSU for extn calls (to provide the energisng voltage). The extension phone should also be a type which will work with a magneto (old GPO phone, not a modern electronic one).

There is also a version of this (Bellset 39) which is built in to an extension base for 200 series phones.

The last bellset 20 I saw in "proper" use was in a shop in Killarney, Eire, about 10 years ago - it may well still be there!

Jim.

Last edited by jim_beacon; 4th Mar 2007 at 4:59 pm. Reason: correct error in Bellset number
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Old 4th Mar 2007, 5:21 pm   #4
AndiiT
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Default Re: Bell Set No. 20

Hi,
The bellset No.20 is a device used to switch one or two extension phones to an exchange line, and should also allow intercommunication between either extension (if two are fitted) and the "Main" (this would be the telephone that is normally connected to the exchange line)

It is an alternative to the GPO plan 5 or 7 (later plan 105/107) extension system which were ahceived using a bellset 39 or 44 (later Planset 625)

I can see no reason why a 10 volt wall wart power supply could not be used to power the bellset no 20, I have seen a wall wart used successfully with the later planset 625 which is normally powered by a (hard to find) dedicated GPO power unit (power unit No.53).

Regarding connecting these to the public exchange, I think that most equipment produced before the 700 series does not actually have approval for connection that said I have not heard of any cases where this has resulted in any action being taken by BT or other service providers. To be on the safe side it may be prudent to connect the exchange line side of the equipment via a pluggable line cord.

More information about all these devices and associated N-diagrams can be found at the following sites -

http://www.britishtelephones.com/

http://www.samhallas.co.uk/repositor...rams/index.htm

I have also included the following links which may help

http://www.samhallas.co.uk/repositor.../0000/N520.pdf

http://www.samhallas.co.uk/repositor...1000/N1428.pdf

http://www.samhallas.co.uk/repositor...1000/N1429.pdf

http://www.samhallas.co.uk/repositor...4000/N4307.pdf

http://www.samhallas.co.uk/repositor...4000/N4308.pdf

http://www.samhallas.co.uk/repositor...4000/N4309.pdf

http://www.samhallas.co.uk/repositor...4000/N4310.pdf

http://www.samhallas.co.uk/repositor...4000/N4508.pdf

http://www.samhallas.co.uk/repositor...4000/N4510.pdf

Regards
Andrew
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